'89 S15 Ecm Computer Troubles

kd7vvg · May 25, 2008

I have a 1989 GMC S15 pickup with 2.8L, 5 speed, that coded out that the PROM was falty in the computer. Curent simptoms are Check Engine Soon light and Shift (arrow) light are on steady, and when engine cuts out they flicker (not code pulse). Early simptoms were a code 15 (I think it was) from the Parking Break light (I have ABR rear ABS breaks only), that coded that the computer was going out. That light only returned once more after resetting computer (but was steady light even after disengaging parking break).

Side note: I recently had my clutch rebuilt, and transmission replaced from used '92 S10. Those apear to work great now, but slight jerking when pickup reaches a coasting state. I think it may be related to the computer issue.

I reciently ordered a replacement PROM ACD#/GM#: 16074658 per ACDelco's instructions, from vpartsinc.com, but I am having the same issues. I was able to drive it for about 35min then parked and when came back it would not run (coughs and sputters). I disconnected the battery for a few hours and was able to get my pickup back home (did not allow it to stall at stops). But problem persists at restart.

I am guessing that the chip I replaced was not the culprit and that it is the other chip stamped 16051460 and 8850 on the top of the chip. NAPA could not cross reference those numbers, and ACDelco was closed for the holiday weekend.

Part number and details are as followes:

1989 GMC S15 pickup with 2.8L, 5 speed (stick) extended cab (VIN: 1GTCS19R0K2524075).

Computer ECM is part# 1228062 (fits other simular vehicles), large chip (EPROM?) part number on chip is ACHZ 4660 (ACDelco# 16074658), and smaller chip (don't know function) number on chip is 16051460 and 8850 (ACD# unknown).

PS: I NEED this pickup right away! I am moving in a couple weeks and will be working 300 miles from home for the Forest Service this summer, so I need my pickup. Could someone please help soon?!

If this needs posting elsewere let me know (Im a newbie here).

Thank you,

Desperate and Defeated

tzh · May 31, 2008

?? any picture /?

tzh · May 31, 2008

without picture,this thread is borring

kd7vvg · May 31, 2008

without picture,this thread is borring

No picture needed. Everything is stock and borring. The truck is not customized or pimped out. Any historical picture of a S15 of the same year will do. Also it looks very much like an S10.

Any way, it turned out that it was not the ePROM after all, it was the computer module that was the culprit. It cost me $276 for labor for them to find issue and swap new computer that I had baught ($97 + $106 for replacement ePROM), but feared to swap myself due to warning message on new computer (if selonyds/relays are not working correctly -something about 20 ohms... burn out computer...)

I should have taken towtruck driver's advice and went with a cheeper (but just as good) garage. Live and learn.

It runs now, though idles slightly faster than I think it should.