: 1989 Deville F32/Running issues..Please Help

12-12-12, 04:17 AM
A friend of mine bought this cadillac for $550....someone messed with it the the point where i replaced the wiring harness behind the dashboard for the speedo/climate/fuel/stereo etc. I also at the same time had to convert from analog to digital because of the wiring difference. That all works all done. Pulled the heater fan out to bench test and it shorts. I also replaced the A/C power module with a used one, now new fan works. The F32 code ive never dealt with but I know that it means communication error between ECM & BCM. I don't have an FSM for the 89' with TBI.. The original (I'd like to think) BCM fried after buddy jump started the fuel and climate went out. I had a spare BCM lying around from a 4.5 PFI/4.9PFI car so I tried it. Seems to have worked other than F32. Went and got another BCM from a PFI car and does same thing. Got another ECM from 88 4.5 deville.....runs worse. I cant find any 89 caddies...almost none have computers..

I made a video of how the car runs etc, i don't have alot of time to screw with it, so if you Gentlemen could shine some light on this car I would really appreciate it. The car ran like this with original bcm. Part numbers for BCM are different on rockauto for 89, 90-93 is the same.


12-12-12, 01:15 PM
89 was the 4.5 PFI engine. Prior years had the 4.5 TBI so wouldnt expect it to work well. 4.9 would probably run poorly due to rich mixture, surprised it even works honestly.

Lack of comms might be the BCM complaining about the ECM version. I would NOT recommend changing ECM as it talks to everything else (injectors, everything engine related). My advice is get on ebay. Also check car-part.com for junkyards that might have. I found a couple of BCMs for $25ish IIRC

12-12-12, 01:44 PM
Ehall, PFI came in 90 4.5, then 91-93 was 4.9. This car is TBI, my caddy is PFI (91). So what youre saying is I should install 89 TBI BCM? What would be the differences between 89 BCM and 90 thru 93 BCM's? They look the same but numbers are different between 89 and 90-93.

12-12-12, 02:31 PM
ah you're right, 88 and 89 were TBI, sorry about that

I would stick to the model years. The BCM controls a lot of crap.

12-12-12, 02:42 PM
Yeah the original BCM doesnt power up the fuel/climate/cluster. But the car runs the same with original bcm or the 90-93 bcm..

12-12-12, 08:28 PM
What about tps, Coolant temp and MAT sensors if they went bad? While BCM throws F15 and F32 codes, it doesnt show any E codes, is it because of the communication issue?

12-13-12, 02:17 AM
the BCM only does F codes, the ECM does the E codes