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Hiya all. I hope someone can help me with this very strange problem. To attempt to find out what is happening, I got 4 manuals (Chiltons, etc) and have searched the internet for countless hours these past two days for a solution... alas none can be found....yet...

I have a 1989 DeVille FWD that I put it in storage 1 1/2 years ago. When I took it out two weeks ago, the battery was dead (duh.. should have removed it.. I know..). I tried to charge it to no avail (again... a duh thing to try ;)) Put in a new battery and gas and tried to start it. It started right up and ran fine... *however* .... after I put my key in and turn the ignition switch to the "ON" position, the blower moter comes on high (out the defrost vents) and a code "c" is displayed on both the Fuel Center Display (in where the number of gallons left would normally be) and the Electronic Climate Control display. I then start the car (which by-the-way starts jut fine), the fan continues to blow on high and both displays continue to read "c". After a few minutes with the engine running, both displays change from "c" to "d"..with the blower fan continuing to run on high. The following is also true:

- Service Engine Soon light is on (although this was on when I put it in storage originally)

- Attempted to extract diagnostic codes (via pressing the Off and Warmer buttons on the ECC and then trying the Fuel Used and Reset buttins on the FCD). Nothing... still c (or d) with blower on high

- Sometimes the Service AC Light comes on... but goes right off

- Unlike some others, my blower fan actually turns off when the car is turned off

- Sometimes... (rarely), when I first start the car, some words and numbers will be displayed on the FCD (like "Fuel Used in Liters".. although the car is in and originally came from the States).. but then the display goes right back to c... then d

- I can repeat the above process as many times as you like... each time gives the same result

Very frustrating... I hope someone can help....

TIA
 

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da_bills2 said:
Could this be a BCM module problem???? Anyone have any clue....
Bill
i`ll bet the farm that your dash lights are on really bright too.

same stuff going on with my 92 deville

The factory tech manual i have says
in the diagnosing and trouble shooting section
if a c or d is present on both panels
to replace the EBCM,located behind glove box module.

BCM can be purchased from BBautoparts.com
check-em out
Don
 

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Thanks for the info. Just so happens the other day everything started working fine. Then, the next time I started the car... c then d ... again. So I think it may be a bad ground or some other bad connection. What I need is the Service Manual for my car so I can check all of the circuts coming out of the BCM. If that fails.... I'll just go ahead and get a ew one from BandB! Thanks for all of your help on this!

Bill
 

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da_bills2 said:
Thanks for the info. Just so happens the other day everything started working fine. Then, the next time I started the car... c then d ... again. So I think it may be a bad ground or some other bad connection. What I need is the Service Manual for my car so I can check all of the circuts coming out of the BCM. If that fails.... I'll just go ahead and get a ew one from BandB! Thanks for all of your help on this!

Bill
Our 92 Deville does the SAME thing will work then not work.

The Bcm is toasted...will let ya all know when i get the new one
and R&R .
 

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:) Hi! I'm having the same c then d problem on my fuel center and climate controls in my 1989 DeVille. I was wondering if you were able to repair yours and if you did, what exactly was the problem and what part do I need to replace? If you could help me, I'd truly appreciate it. :worship: Thanks
 

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Hiya -

After doing extensive investigation I believe it is the BCM which is located right behind the glove box. I got mine out in under 10 mins. (Glove box comes out with 1/2 dozon screws or so, then remove the black plastic cover that goes over the air ducts) I ordered mine from B&B in NY. Will let you know what happens when I replace it
 

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Thanx sooo much! I will be anxiously waiting too hear the verdict. I know that the BCM is located behind the glove box, but could you give me a description of what it looks like. For example, what colored wires if any are coming off it. This may seem like a really silly question...sorry. Just became the owner of this car only a few days ago. Thanx so much for your time. Happy New Year to all my fellow Cadillac owners. :cheers:
 

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Before I Would Replace The Bcm, I'd Ck The Central Power Supply Module Located Above And To The Right Of The Brake Pedal. Locate The Module And Wiggle The Wiring Plug To It. It Measures Approx. 8 Inches By 6 Inches, Silver In Color Mounted Vertically. Two 10 Mm Nuts Secure It To A Bracket. Model Numbers Should Be Something Like 16060456. They Improved This Module And Superceded The Numbers, But It Still Starts With 16060 I Believe. Hope This Helps. I Got Mine At A Self Service Wrecking Yard. Its Function Is To Regulate Power To The Bcm, Keep It Constant Allowing No Major Change In Supplied Voltage.
 

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Discussion Starter #10
Carnut -

Thanks. Will look and see if I can find the power supply. Do you know if this is the only thing that supplies power to the BCM? (or conversely is the BCM the only thing this supplies power to?) or does the BCM also get power from other sources as well (i.e. does the BCM have multiple power inputs?) If the Central Power Supply Module is indeed the only source of power for the BCM and it only supplies the BCM with power, it could very well be my problem. I do need a manual for this car desperately!

mbrakall -

The BCM is a silver rectangular box that is mounted vertically to the firewall by 3 or 4 10mm screws. In addition, there is a black plastic piece that you must remove because it goes right around the box and connects to the air ducts. Once you remove the glove box, you can't miss it! I've included a (very) crude diagram of the BCM as it looks when it is mounted on the firewall


+-------------------+
| +-+ |
| | | |
| +-+ |
+-------------------+
 

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Thanx for the information carnut, but unfortunately we were unable to locate the cental control module in the location that you've specified. Is it possible that on the DeVille it is in a different location? My fuel and climate readings came back on for about five minutes or so last night, making everything you've said make complete sense.
 

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I asked for help in another forum at a different website for my 'c' then 'd' problem and here is the response I got.

You should check your gm dealer for PSB #89-8-129 or T 90-31. You will have to add two capacitors to climate control panel and fuel data center.GM part number is 1227895,you will need two of this number. Solder the positive or striped end to terminal T and other side to terminal S in both the CCP and FDC. Please have a copy of bulletin before you do the repair.

:bonkers: That sounds too scary for me to even attempt to try. If I were to try this, my car would probably never leave its parking spot again because I can see me frying everything. But maybe this might help someone else, if so, Good Luck.
 

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I have the same problem with my 93 Deville and it is the BCM is what my local Mechanic says also everything I have read in these forums points to that Thanks for all the great help
 
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