Cadillac Repair: 1989 Fleetwood,s problems between ECC, FDC and BCM, electronic climate control, cadillac fleetwood

Question
QUESTION: Hi Tom

I have –89 Cadillac Fleetwood 4.5 V8 and it has this problem that the electronic climate control (ECC) and the fuel data center (FDC) goes both crazy while after while for few minutes  or they jam completely. Usually they start to work after few minutes, sometimes it help if I start the engine again but the problem cam come back after a while. I have checked the trouble codes and they are F30 and F31, meaning that there is a connection loss between ECC (F30), FDC (F31) and BCM. I have cleaned both ECC and FDC and I have also cleaned connections from BCM. I also have measured the wires between these modules and all the relays and fuses and they all seems to be OK. So is it so that the BCM is broken or what?


ANSWER: Have you ever see these symbols on any of the displays:

-c
-d
-151

If so, the BCM is at fault. I would replace the BCM anyway even if they do not appear.

---------- FOLLOW-UP ----------

QUESTION: Only symbol I have see was letter L in the FDC display yesterday when I take the battery off and put it back again.

Answer
Disconnecting the battery will NOT clear the CODES. All you are doing is messing up the computer settings.

CLEAR (erase ) the CODES from the computer and see which if any codes return as "E" codes or "EE" codes or "F" codes or "FF" codes.

To CLEAR the codes:

1. Ignition ON. Engine OFF.

2. Simultaneously push and hold the OFF and WARMER buttons on the climate control panel for 3 seconds and release them.

3. Diagnostic codes will appear and then the display will stop at .7.0

4. To clear any "E" codes, Simultaneously push and hold the OFF and HI buttons until E.00 appears and release the buttons.

5. To clear any "F" codes, Simultaneously push and hold the OFF and LO buttons until F.00 appears and release the buttons.


6. Turn ignition OFF.

Wait 3 minutes and re-enter diagnostics per above and see what CODES you get. Codes will appear as either "E" or "EE" codes and "F" or "FF" codes and will stop at .7.0

I need to know EXACTLY how the codes display as if you were video taping them.