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Old 06-23-08, 12:37 AM
wachuku wachuku is offline
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Cadillac(s): '97 Seville STS
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Advice on what to do to resolve codes

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Problem: '97 STS seemed fine; now it won't start.

Background: Over the course of about a week, the car's "health" deteriorated as follows: (i) running fine; (ii) rough start; (iii) rough start and won't reach RPM above ~2000 RPM without restart, then run fine; (iv) rough start and stalling every 100 ft; (v) won't start.

Prior to all this, I inadvertently "deep cycled" the battery with the engine off to the point where I needed to jump-start the car. Symptoms (iv) and (v) didn't appear until this weekend, so I was working under the assumption that I wrecked the battery, it wasn't holding a good charge, and was causing rough starts and maybe also computer glitches that were followed by seemingly perfect operation after restarting with more charge in the battery. During this time I was also monitoring voltage which would always display as 13.7 to 14.4 shortly after startup, so I assumed I didn't torch the alt.

In the process of getting a new battery this weekend however, the car exhibited symptoms (iv) and (v). Now although the car turns over nicely, it won't start at all, even with a new battery and a jump.

Here are the codes (all "history"):
  • PCM
    • P0603 - Control Module Long Term Memory Reset
  • IPC
    • B1552 - Keep Alive Memory (KAM) Error
  • SDM
    • B1159 - Loss of Serial Data-Key Not Received
    • B1160 - Loss of Serial Data - VIN Not Received
    • B1163 - Loss of Serial Data-No Lamp Response
    • U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)
  • TCS
    • U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)
  • PZM
    • U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)
  • IRC
    • U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)
    • U1064 - Loss of Communications with DIM
    • U1096 - Loss of Communications with IPC

I run codes routinely, and I know I didn't have any of these prior to deep-cycling the battery. On the other hand though, maybe in light of "U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)", the battery problem is a "red herring". Is there an easy way to check the integrity of serial data line communications? I'm not $o $ure I want to $eek the $ervices of a techII if I can avoid. I hope these codes don't mean a reprogramming of some sort will be required.

====================================

For anyone who might be interested in even more info, below are the codes I received during the middle of last week, when the car seemed run run perfectly if either of the following two startup conditions were met:
  • not long time off (e.g. less than over night) -- run perfectly
  • restart after start and idle for 30-60 sec -- run perfectly

Codes when the car would run (all "history"):
  • PCM
    • P1604 - Loss of IPC Serial Data
    • P1605 - Loss of HVAC Serial Data
    • P1610 - Loss of PZM Serial Data
    • P1626 - Theft Deterrent Fuel Enable Signal Not Received
  • IPC
    • B1552 - Keep Alive Memory (KAM) Error
    • B1910 - Generator L-Terminal Open Circuit
    • U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)
  • ACM
    • B1983 - Device Power Circuit Low
    • U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)
    • U1096 - Loss of Communications with IPC
  • SDM
    • B1159 - Loss of Serial Data-Key Not Received
    • B1160 - Loss of Serial Data - VIN Not Received
    • B1163 - Loss of Serial Data-No Lamp Response
    • U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)
  • IRC
    • U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction)
    • U1064 - Loss of Communications with DIM
    • U1096 - Loss of Communications with IPC

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One difference between when the car would and would not run is the emergence of the code "PCM P0603 - Control Module Long Term Memory Reset". Is this the likely culprit, and if so, is there a way to fix it?

Hoping for some insights.

Last edited by wachuku; 06-23-08 at 12:41 AM.