HT4100 4.1, 4.5, 4.9 Discussion, 1987 DeVille Conv. 4.1 ICM still sets idle to high in Cadillac Engine Discussion; Originally Posted by BigCadMan_1
I hate to chime in on this one but I had the same problem with a ...
Re: 1987 DeVille Conv. 4.1 ICM still sets idle to high
Originally Posted by BigCadMan_1
I hate to chime in on this one but I had the same problem with a 1986 Sedan deVille. I work part time as a mechanic & the owner of the garage was a trouble shooter for Alfa-Romeo & a master mechanic for Audi. We have anywhere from 20 to 30 cars a week come through the shop & trust me when I say we see it all. Why am I telling you all this, because I had all the resources one would need to fix this problem & we could not. I replaced every part with-in the ignition to fuel diagnostic tree, replaced both ECM, BCM's & still zip! Paid GM 2 hours to trouble shoot & nothing but $200 bucks poorer! I traced every path from the fuse panels & was getting ready to do the same for all the relays but gave up! In the end we thought it might be a short somewhere in the wiring harness but like I said I gave up after 3 months and countless dollars. I disconnected the ISC (or else the car was unsafe to drive) sold the car as is & paid some back tax's.
I have no advice for you, just this story. Take it as you like.
BTW I'm sure carnut will chime in & give a good idea where to look next, I hope for all the best for you.
Originally Posted by cadillac_al
Hey bigcadman, did you try a new ISC on this adventure? And a new one still didn't fix it? That would be depressing.
Yes, "I replaced every part with-in the ignition to fuel diagnostic tree" just to be clear here I'm not saying it can't be fixed, I'm just saying I could not fix it.