Cadillac used color coded ribbed vacuum hoses from the 60s to the late 70s to make it easier to identify them on the vacuum schematics in the shop manual.
These vacuum hoses unfortunately get extremely hard and brittle over the decades under the harsh conditions in the engine bay. Often they literally break into pieces by just touching them.

On my 67 Eldorado I had to replace most of the vacuum lines when I got it - and it really has a lot of hoses.
When I searched for reproductions I could not find a really good source and I gave up.
At my ongoing project on my 74 another of these original lines fell apart while working in the engine bay. So I started to look for the correct hoses once again.
Soon I found a link on ebay to a well known seller, whose name I do not want to mention, offering the lines in all the colors I needed.
I ordered quite a few Ft of each color.
The seller describes them as factory correct and as a perfect part - see screenshots below.

As they do not ship to Europe, a friend of mine was so kind to forward the hoses to me.

When they arrived I was shocked - I have never ever seen a worse product.

The paint is peeling off or missing at all. As soon as you even slightly bend the hoses, the paint on the stripes just cracks and falls off. It could not be worse.
Also the hoses are too thick and the walls are to thick. The original hoses are quite a bit slimmer than these crappy reproduction hoses.

They also charged me for 15ft of red striped hoses but only sent 10ft. This was about the worst buying experience ever.
I´m trying to return the hoses at the moment - but communication with this seller is terrible.
I normally never criticize sellers here on my website and never leave any negative comments on ebay - but this is the worst I have ever experienced.

Shipping back these hoses will cost me at least $50 and I already paid $60 for having them shipped to me in Europe - with the import tax I will have lost $160.- for this BS… Money I would urgently need for some other parts… :-(

I´m now trying to find another good source for quality reproduction hoses. There is one Corvette parts dealer which looks promising as he offers some great kits for Corvettes, but they are all pre-cut… I hope he can send me some ft. of the hoses I will need - I hope that I will get a positive reply.


Ebay seller screenshot - this is how they describe the hoses…
As you can see the paint stripe is just cracking everywhere.edge
As you can see the paint stripe is just cracking everywhere.edge
As you can see the paint stripe is just cracking everywhere.edge
As you can see the paint stripe is just cracking everywhere.edge
As you can see the paint stripe was not even painted correctly on the green hose…



Whenever I connected the battery on my 78 Eldorado - the interior lights came on, and after about 15-20 seconds they would start flickering and turn off with a strange noise.
It took me a while to find out what was going on, but eventually I could track it down to the illuminated entry system relay.
Sometimes the interior lights would not come on at all, as they should when the car was locked and I pushed the door button from the outside, or the lights would only flicker, and one could hear a relay making a ratcheting sound.
After a while it dawned on me that the illuminated entry relay must be faulty.
After browsing on ebay for months, I found an offer for an NOS relay, which is extremely hard to find and not available anywhere, as this system was an extra cost option in 1978.
After mailing back and forth with the very well informed and nice seller, I began trying to locate the relay in my car to compare it to the one he offered. Two different ones where used in 1978. They came from two different manufactures but were interchangeable. They have different terminal locations which do not matter though, as there were two different connectors used which you can connect to both models. The part number for the relay is #3063206 - it's the same for both models.

It took me a while to figure out where the relay was hiding, as the factory shop manual did not reveal its location.
I finally found it behind the drivers side kick panel. You have to remove quite a few of the interior panels and the door sills to get access to it. Another problem is that the kick panel is connected with the hood release lever and cable, which makes it very difficult to remove. Luckily I could spread it open wide enough to access the relay without removing the hood release cable, which would have been a pain in the butt to get out.
I removed the relay and compared it to the one I found on ebay, and it was identical to the one which was offered. So I hit the "BUY IT NOW" button immediately as I was concerned that somebody else could buy it.

I then opened the relay up. I wanted to take more pictures, but the battery of my phone died, and I had no other camera at hand - thats the reason why I unfortunately do not have more pictures of this repair.

Everything looked good inside, but then I found out why the relay did not work properly.
It should be mounted to the car with a screw which acts as the ground for the relay, which acts as a 20sec timer for the illuminated entry system.
But there was no screw on the relay… After further investigation I found a broken screw underneath the carpet, and the rest of the screw was stuck inside the screw hole.
It looks like the screw already broke off when the car was assembled and nobody cared as it might have worked for a while… Sometimes the system worked and sometimes it didn't… Probably the owners did not even notice the problem - it took me about a year to notice it as well…

I had a hard time getting the broken screw out of the hole, but after fiddling with it for about an hour, I got it loose and could screw it out. Luckily I had a spare screw and reinstalled the original relay with the new screw, and voila - it now works perfectly again. It probably never worked that good before - even when the car was new…
Too bad I had already ordered the new relay - but at least I have a spare NOS part now, which I will hopefully never need!

My original relay after I opened it up
The NOS relay I found on ebay - part # 3063206 - its exactly the same one as I originally have in my car. It is made by Philips.
The NOS relay I found on ebay - part # 3063206 - exactly the same one I originally have in my car. It is made by Philips.



I just recently found out that the power antenna in my 78 Eldorado is not the factory correct one anymore.
My Eldo comes with a radio with the CB option, so it should have the according tri-band antenna for the 78 Eldorado.
One of the previous owners had replaced the original antenna with a replacement antenna, which worked, but it had very poor CB reception and of course it does not look correctly.

What I have found out is that #22010515 was the original part number for the antenna.
This antenna was also used in the 1977 to 1982 Corvette and is extremely rare...
Replacement antennas had the part number #22010661 on the sticker with a date code below.
When these replacement antennas were no longer available, it seems they switched to a different antenna design as a replacement #12355706 (which I had in my car). This last design came with a special antenna splitter. I do not know if this splitter is essential or of it would also work with the original splitter which is still in my car.

It took me quite a while to find the correct antenna for my car as it seems to be made out of "unobtainium". I did search the net for days and somebody sent me an incorrect antenna which was for a Buick… Suddenly during my daily search, a correct, working antenna showed up on ebay, and I immediately hit the "Buy it now" button. It was not exactly cheap, but I was happy to have finally found it. When it arrived I cleaned it up properly.

I then found out that I would also need the correct antenna bezel on the fender. Various sellers sent me incorrect ones which they claimed would be the correct ones, and eventually I found a good used one from the seller of my antenna and a NOS one from a parts vendor (it has not arrived yet as once again USPS sent it to Australia instead of Austria - don't ask what this little bezel has cost… :-( )

I then also had to replace the thinner replacement antenna lead with an original one going from the antenna splitter behind the glove box to the antenna. I got this one from Arizona Vintage Parts.
I can say now that my car is 100% correct again. Unfortunately this project was an extremely expensive project and I will now try to sell all the not needed parts on ebay. They will fit Eldorados with non CB antennas and the other wrong CB antenna I got will be for Buicks, but could also be installed into the 78 Cadillacs, as the mast itself is exactly the same as on the original antenna and from the outside it would look completely stock. But purist as I am, I just needed the 100% correct antenna ;-)

The later style replacement CB antenna which I wanted to replace with an original one.
The later replacement style fender bezel looks completely different from the original one.
On the left you can see the official later style replacement CB antenna which looks very different. It does not have a load coil and no additional stub antenna. This is part #12355706. On the right you can see the original 1978 CB power antenna with the load coil on the mast and two antenna leads and the additional FM stub antenna. This antenna is nearly impossible to find…
Thats the CB - load coil, which can be adjusted. The plastic unfortunately got very brittle over the years on all antennas of this vintage.
This are the instructions which came with the car, if you ordered the very expensive CB option…
The antenna trim bezels for the 1978 Cadillacs. On the left the one for the regular antenna - on the right the one for the CB antenna with a larger diameter in the plastic part. The chrome ring is exactly the same for both. These two are used ones I found.
I cant believe that I was lucky enough to find this super rare antenna bezel as a NOS part - still wrapped in its original plastic bag. Not exactly a bargain, but its 100% perfect.
The new, correct antenna installed into the car.
This is the incorrect CB antenna I got. It could be installed into a 78 Eldorado without any problem and would look 100% correct from the outside. It works perfectly smooth, and the chrome mast is in excellent condition. The load coil and the FM stub antenna are all there. The previous owner of this antenna removed it from a 78 Eldorado, but it would normally be correct for Buicks. If you are not such a purist as I am, you can buy it from me for what I paid for it. ($250 + shipping) It comes with all the necessary hardware to install it.



***This is an update to an older article as I had a very similar problem in the past already.***

I finally found the time to take the 1978 Eldorado out of winter storage. It started right up after many months of inactivity and I checked all accessories and options for operability.
Everything checked out fine but the air-condition… It only blew warm air out of the heater outlets and would not change modes, blower speed or temperature.

I immediately suspected a problem in the ATC programmer again. I already fixed it last year when the system would only work in full AC mode.
Last time I had a bad contact at the transducer which is the most important part in the programmer as it regulates the vacuum supply to the system.

The shop manual mentions that when the system is stuck in full heater mode, most probably an electrical problem is the main cause.
So I tried to push the transducer in again but the system did not come back to life like it did last time when I did this.

The MKII programmer which you can access through the glove box had to come out again for inspection.
This is how it looks with the cover removed:

The 1978 MKII programmer with the cover removed.

I decided to take the transducer/amplifier board out of the programmer this time to see where the problem could be. It can be removed very easily - it's only held in place by 4 screws. Be careful not to turn the gear wheel with the potentiometer though as you would have to recalibrate it again afterwards.
After the board came out, I quickly found out where the problem was. Below is a picture of the removed board:

The transducer/amplifier board.

The transducer/amplifier unit was sitting pretty loosely on the circuit board, and one of the very thin and fragile wires going to the coil was broken, as you can see on the picture below:

A broken wire at the coil of the transducer.

When I turned the circuit board around I could see that the soldering points on the circuit going to the transducer and the amplifier were broken and that they no longer were making good contact. That was the reason why the system did no longer work.

Broken soldering points at the rear of the circuit board.

The pretty simple solution was to re-solder the 3 soldering points and fix the broken wire going to the coil. I then put everything back together and now have a perfectly working ATC again. These old circuit boards can be very troublesome and I think that most of the time when a programmer goes bad on these 70s cars its probably a fixable problem like this. I was very worried that I would need an expensive rebuilt programmer and I am very glad that I could fix it by myself.
I have no idea though why everything worked when I put the car into storage last fall and how it broke while the car was inoperative…

Check my older post of the MKII programmer to also see the electrical diagram for the ATC system.



You have to remove the ashtray and part of the lower dash to get the radio out.

Before the spring season will start in May, I want to make sure that all my cars are in top notch condition until then.
The radio on my 78 suddenly died last summer. I was driving the car and the radio and 8-track and CB worked flawlessly. It had great sound and everything worked.
Suddenly, when I wanted to turn the volume down a little bit, the antenna retracted, and the radio went off completely and I could not turn it on again. I also could no longer operate the power antenna.
When I was home I discovered a blown fuse and replaced it, but it immediately blew again when I wanted to turn the radio back on.

I took the radio out now, and measured the power source, and I can clearly see that there is a problem somewhere inside the radio.
It looks like the power source is defective.

My friend Steve who is really good in repairing older radios offered to have a look at it. Unfortunately I cant fix this myself, as I have no clue how this could be repaired, or what could be defective…
Its great to have such good and competent friends who can fix such things.
In a very short time Steve found out what was wrong with the radio. One of the many condensators on the radio got dry over the years and caused a short. Steve replaced the broken condesator and even replaced all the other old ones with new ones to make sure that the radio will last for a long time.
I can´t thank Steve enough for fixing the radio for me. It is very important for me to know that it works again - I hate when things do not work properly on a Cadillac.
When I installed the radio back into the car, it came back to life, but the FM functionality did no longer work, and it was stuck in AM mode. 8 track and CB worked perfectly, but I could not switch to FM mode.
So Steve was so kind to disassemble the radio once again, and found the problem with a disengaged spring which could no longer activate the AM/FM switch.

The radio is out of the car - it's the one with 8-track and CB - the most expensive one available in 1978. You can see the replaced condensers on top of the radio.
This bigger condenser was the cause for the trouble - it got dry inside and caused a short. The others were exchanged as well as a precautionary measure.
The back side of the radio.
You have to remove the ash tray assembly to get the radio out

The radio works again and is back in the dash. 8-track and CB work perfectly as well.

The GM demo tape which came with the car sounds amazingly good. Love the sound.

While I was working on the car I finally repaired the glove box light switch which had a problem since I got the car. I got a new switch from Arizona Vintage Parts and it now works perfectly again.

The glove box light is back in working order.


I also replaced the cars original hot water valve, which had a leak at the vacuum diaphragm and could not close any longer.
I found a perfectly working NOS replacement on ebay for it, as the one I got from Rockauto before looked completely different.

The new hot water valve in place.


Fixing the 1978 Cadillac Eldorado´s ATC programmer. The AC works again.


An update to the article below can be found here as I had to repair the programmer again in May 2015:

The air-condition in my 1978 Biarritz did not work correctly. For some reason the system always stayed in full AC mode and no matter to where I put the temperature dial on the control head I could not get the heat on, no matter what I tried.
The shop manual is very helpful in trouble shooting the system. Its covered in the 1977 factory shop manual (FSM) as there were no changes made to the system in 1978.
It took me a while to fully understand how the system works - so I had to read the FSM multiple times to get the grip what is going on in the system.

First I inspected all the vacuum lines in the car to make sure that there was no leak anywhere, as the heating mode requires a very high vacuum at the vacuum motor in the controller.
All lines were in very good condition. I also checked the control head connections in the dash which were good as well.
I then suspected the vacuum motor in the programmer as it did not move. I removed the programmer from the car. You can access it from underneath the dash on the passenger side or even better if you remove the glove box lining through the glove box.
From there you only have to unscrew 5 screws, unplug the wires and the vacuum lines to get it out.

When I had it out of the car I checked the vacuum motor. I just sucked air through the hose and it moved and held vacuum perfectly.
The transducer or the amplifier in the programmer were most likely the problem.
When I checked the transducer which regulates the vacuum supply to the vacuum motor, I noticed that it seemed to not be connected to the electrical board as it should. I pressed it in, so that it made good contact with the board again and put the programmer back into the car and connected everything again.

***UPDATE 2015 - its not connected with pins but soldered to the circuit board - 3 of this soldering points were broken - the “repair“ I made here only temporarily worked. You have to check the soldering points for a permanent fix***

I started the car and the AC came back to life again immediately. I could see how the vacuum motor went through all the modes as it should according to the position of the temperature dial on the control head.
The build quality of the programmer obviously is not very good and the transducer somehow came loose causing the ATC to not work as it should. ***Update 2015 - it did no come loose but the soldering points broke***
After I tested everything I put the parts back together and can now enjoy a full working ATC in my 78 Biarritz again ;-)

The programmer as seen through the glove box with the connectors and the plastic case removed

The 1977 / 1978 Eldorado MK II Automatic Temperature Control Programmer

The transducer which caused the problem (the golden part with the single vacuum line going into it)

The transducer is connected to the electrical board through a couple of pins - it was not connected properly and somehow became loose over the years - that was why the system did not work.
***UPDATE 2015 - its not connected with pins but soldered to the circuit board - 3 of this soldering points were broken***

The vacuum checking relay and the electric connectors.

The vacuum power motor
from the 1977 FSM

Trouble shooting guide for when the system works in full AC mode only.

A color coordinated electrical schematic with annotations to describe the various functions of the system.


Detailing the paint of my 1978 Biarritz.

I continued to work on the 78 Biarritz during the last few weeks.
My goal is to make this mint car as good as it can get, while keeping everything as original as possible.
I´m really obsessed with cleanliness when it comes to cars... Everything has to be completely detailed and shining like new.
I completely cleaned the entire engine and gave it a good wash and afterwards applied some engine dressing.
I then removed some screws and small parts which were left unpainted by the factory, like some screws, the hood latch, some brackets and some other smaller parts. Of course these parts developed some slight surface rust during the last 36 years...
As I had no real rust dissolver at hand, I soaked the rusty parts in vinegar over night, which completely removed all the surface rust. I then gave these parts a coat of primer and painted them with Eastwood paint, which looks like bare metal.
With this method I can keep the rust away, while the parts still look original. Only if you look very closely you might see that these few parts are now painted...

I then started to bring the original single stage paint back to like new condition.
I used a couple of Meguiars compounds and polishes to make the paint as smooth as possible. I had to carefully wet sand some of the deeper scratches with 2000 grit paper. Be very careful when doing this as the single stage paint was applied in only VERY thin layers during the 70s.
The car now shows almost no more paint imperfections and the swirl marks are gone. The original paint looks like on a new car now and is extremely shiny. When the car is out in the sun its almost blinding.
I sealed the paint with Meguairs #16 wax.

I used a Meguiars DA polisher (G125) for the paint correction work - which is not really that good, but I would like to have a more powerful machine for the future like the Flex 3401 or the Rupes Bigfoot .

I used the procedure explained in the following video for my paint correction:

Download his description as PDF file here

This gentleman, Larry Kosilla, has a lot more awesome video tutorials for people who love detailing their cars. Check him out!

I also started detailing the interior of the car. I treated the leather with Gliptone Leather Conditioner - which is the best conditioner I have tried so far. It really makes the leather very soft.
I´ll have to steam clean the carpet once its really warm outside so that it can dry fast afterwards.

I also cleaned the undercarriage a little and removed some of the factory applied undercoating from components where it does not belong to, on which they sprayed it on very carelessly at the factory. Looks much better now.

The car really looks spectacular already - I´ll continue with the chrome and stainless steel trim now. It should be shining in fully glory for the 2014 season beginning in May and also be ready for various car shows, especially the Cadillac BIG Meet in August.

My weapons of choice came from the Meguiars dealer...
before and after cleaning
rusty bolts before and after cleaning
Soaking rusty parts in vinegar
Cleaning more rusty parts
with the rust removed
The Hood latch cleaned and painted with Eastwood Silver Cad Paint
The cleaned engine bay

The car after polishing the paint

the polished paint
very shiny
Besides the carpet - the interior is already perfectly clean. The original floor mat is under the aftermarket mats.
Cleaning the Vogue tires.
Clean paint and tires
Clean tires and perfect hubcaps
Before waxing

I really like this Meguiars wax. Its one of their cheapest but best waxes. A gentleman from Meguiars once told me that it is one of their oldest waxes, but contains a lot of carnauba wax, which makes it so good! Its also offering the best protection of their product range.

Here are some links to Meguiars products I like to use (link to german Amazon Shop):


1978 Eldorado - Choke problems.

After I cleaned the engine bay of the new Biarritz I drove the car out of the garage. The car started beautifully, but for some reason it would not idle down and run on fast idle speed - even when it was fully warmed up.
The only way I could get it to normal idle speed was to manually release the fast idle cam on the carburetor. For some for me unknown reason it did not release itself - even when the car was fully warmed up...

As I´m not exactly an expert when it comes to carburetors, it took me a while to figure out what was going on and what the problem could be.

I got myself the Rochester M4MC / M4ME Carburetor Manual online and started reading. The trouble shooting section did not mention my problem and symptoms though, at least I learned a lot by reading through the manual...

The carburetor in my 1978 Eldorado is a Rochester M4ME # 17058531 (late Federal).

After a lot of reading I suspected that the electric choke thermostat must be the problem.
I removed it to test it like it is described in the manual.

Electric Choke Diagnosis and Checking

In order to have good engine performance during warm up and be able to pass Federal exhaust emission standards, the electric choke must function properly .

Possible reasons for the choke not operating properly are listed below.

1. No engine oil pressure.
2. Malfunctioning oil pressure switch.
3. No current to oil pressure switch due to:
a. Burned out 15 amp "radio -idle stop" fuse.
b. Broken wire to switch (18 brown/double white).
4. No current between choke coil and oil pressure switch due to:
a. Broken 18 light blue lead wire.
b. Wire terminal not locked on coil terminal.
c. Ground circuit incomplete between grounding plate of choke assembly and housing.
5. Failed choke coil assembly.

A voltmeter or continuity light may be used to check the circuits for continuity to the oil pressure switch and the choke coil.

If it is suspected that the choke coil assembly has failed, the following check may be made.

1. Remove coil from carburetor and cool to room temperature (above 60°F).
2. Attach a jumper wire between positive battery terminal and terminal of coil assembly. Attach a second jumper wire between negative battery terminal and grounding plate of choke coil assembly.
3. The tang of the coil should rotate 45°in 54 to 90 seconds.
4. If coil fails to rotate or exceeds the above timing specification, replace coil assembly.
5. If coil is within above timing specification then coil is good and problem is elsewhere.
6. Reinstall coil and set to proper index (Fig. 52).
If coil is cooled off sufficiently the choke valve will close when throttle is opened slightly. Attach a jumper wire between the positive battery terminal and choke coil terminal. Choke coil should warm up and the choke blade can be observed opening, indicating a good and properly grounded choke coil assembly. At room temperature the choke blade should be wide open in approximately 90 seconds.
If the choke does not operate properly after the coil has been proven satisfactory , check out the other possibilities that prevent current from getting to the choke coil.

After I performed the test procedure above it was clear that the choke coil was the problem.
I ordered a new one from and it arrived within 3 days. The manual mentions the original part #17059968 (the original one on my car showed #17059969 though - but every parts list I checked does not list this number...?).

I got a replacement from Airtex # 2C1045 and it seems to fit.
I installed it today and the choke works as it should again.

This was the original choke thermostat on the car . #17059969
The Airtex replacement part in the car.

The original part and the new part - slightly different at the tang of the spring - but it works and fits perfectly...

original and new part

The Airtex replacement choke thermostat


1978 Cadillac Eldorado - defective door jamb switch repair.

I´m fully detailing the 78 Biarritz at the moment. During this I think I found the only non working gadget this car offers. The 78 Biarritz came with an automatic seat back release. When you open the door a solenoid engages and you can fold the seat back without pushing any button or lever to allow rear passengers to get in or out of the car. When you close the door again the seat lock engages and the seat back stays in position.

I also have the same system on my 1971 Lincoln Mark III where I had some problems as well in the past with a loose wire.

On the Biarritz the passenger side worked flawlessly, but on the drivers side the solenoid would not engage.
I started my search for the problem at the top of the two door jamb switches which is the one controlling this function.
When I wiggled it and pulled it out, I could hear the solenoid engage. So I knew that the problem must be with this switch.

Unfortunately it's not easily accessible. As I do not have the 1978 shop manual yet - it took me a while to figure out how to access it.
I managed to get to it through the lower dash and to uninstall it.
As it turned out it was slightly bent and did not make good contact once the door was opened.
I carefully bent it back straight - and after some trial and error it was back in working order.
It took me a good hour to fix this.

Now I´m back to cleaning the car to my standards, something that will probably take the whole winter...

The upper switch is controlling the seat back solenoid. (Picture was taken before cleaning the door jambs...)

The removed door jamb switch. When the door is closed no contact is made and the solenoids are not energized causing the seat back to be locked in position.
You can see that the switch was slightly bent - making no good contact.

When the door is open contact should be made and the solenoid should energize... The switch did no longer make a good contact though.

I had to remove the lower dash to access the cables on the rear of the door jamb switch through a tiny hole and disconnect the connector with a long nose plier...

I´m now in the long process of thoroughly cleaning the engine bay to look like new again...