1989 Gmc S15 66,000 Miles (v6 4.3)

[jeffm5690]

My wife's first car/truck is out of the garage after about 10 years and runs pretty good. It's a bit rough so after a tune up I took a new code reader to it and wanted to see what I got back. OMG!!! I have the following codes:

 

14 - Coolant Sensor - Signal Voltage low or shorted

 

31 - CAM Sensor Circuit Problems, Park/Neutral Switch

32 - EVRV Error, EGR Valve Diagnostic Switch - closed on startup, MAP Sensor Signal - low voltage

33 - MAP High Voltage During Idle

34 - MAP Low Voltage During Ignition On

 

41 - CAM Sensor Failure, Cylinder Select Error, EST Circuit Open/Shorted, Ignition System Fault

43 - ESC - Circuit Problems, EST Low Voltage

 

51 - Computer Problem - Faulty, wrong or incorrectly installed PROM or ECM/PCM Failure

52 - Calibration Package Chip or ECM Fault or Oil Temperature Sensor Fault/Low Engine Temperature, Faulty or Missing PROM, ECM Problem, High Voltage

53 - System Voltage to High (>17.7 volts to ECM) or EGR System Fault or Alternator Voltage Not Normal or Vehicle Anti-Theft Fault

54 - Fuel Pump Circuit Fault or Mixture Control (M/C) Solenoid Fault or ECM Fault, Fuel Pump Relay

55 - ECM Fault or Oxygen Sensor Circuit Fault

 

I REPLACED:

 

EGR VALVE

PCV VALVE

MAP SENSOR

WIRES, etc.

 

I disconnected the battery after trying to clear the codes with my Innova 3140b and still could not clear them. At this point I think the ECM must be failing since there were multiple codes pointing to that and that could be causing everything else.

 

Anyone venture a guess or some guidance here? I have no clue what to do next other than the ECM and see what happens then...

[takkotime]

My wife's first car/truck is out of the garage after about 10 years and runs pretty good. It's a bit rough so after a tune up I took a new code reader to it and wanted to see what I got back. OMG!!! I have the following codes:

 

14 - Coolant Sensor - Signal Voltage low or shorted

 

31 - CAM Sensor Circuit Problems, Park/Neutral Switch

32 - EVRV Error, EGR Valve Diagnostic Switch - closed on startup, MAP Sensor Signal - low voltage

33 - MAP High Voltage During Idle

34 - MAP Low Voltage During Ignition On

 

41 - CAM Sensor Failure, Cylinder Select Error, EST Circuit Open/Shorted, Ignition System Fault

43 - ESC - Circuit Problems, EST Low Voltage

 

51 - Computer Problem - Faulty, wrong or incorrectly installed PROM or ECM/PCM Failure

52 - Calibration Package Chip or ECM Fault or Oil Temperature Sensor Fault/Low Engine Temperature, Faulty or Missing PROM, ECM Problem, High Voltage

53 - System Voltage to High (>17.7 volts to ECM) or EGR System Fault or Alternator Voltage Not Normal or Vehicle Anti-Theft Fault

54 - Fuel Pump Circuit Fault or Mixture Control (M/C) Solenoid Fault or ECM Fault, Fuel Pump Relay

55 - ECM Fault or Oxygen Sensor Circuit Fault

 

I REPLACED:

 

EGR VALVE

PCV VALVE

MAP SENSOR

WIRES, etc.

 

I disconnected the battery after trying to clear the codes with my Innova 3140b and still could not clear them. At this point I think the ECM must be failing since there were multiple codes pointing to that and that could be causing everything else.

 

Anyone venture a guess or some guidance here? I have no clue what to do next other than the ECM and see what happens then...

 

As stupid as this sounds, because its been sitting so long I would disconnect the neg post from the battery - wait an hour or so then hook it up and take it out for a spin. I bet you anything that you wont have half of those codes when you come back.

I dont know why but my 88 and 89 both do this after sitting - they throw so many codes they shouldn't even run - after running for a bit and going 25 miles or so they almost always clear (with exception of evap or o2 which i have to reset the computer again to get rid of)

try it, can't hurt

 

Also have you checked the voltage to the ECM?

-Takko

[jeffm5690]

It looks like nothing has changed. Funny thing is the codes won't even clear. The only code that cleared was 43. I am thinking the swap of the ECM may be the best course of action. I am looking to order the service manuals and electrical diagrams to do some further testing.

[Duelin]

It looks like nothing has changed. Funny thing is the codes won't even clear. The only code that cleared was 43. I am thinking the swap of the ECM may be the best course of action. I am looking to order the service manuals and electrical diagrams to do some further testing.

 

If you look at #53 (system voltage too high 17.7 volts). The first thing I would check is the voltage. If it is that high it might have fried the ECM.

[jeffm5690]

It looks like nothing has changed. Funny thing is the codes won't even clear. The only code that cleared was 43. I am thinking the swap of the ECM may be the best course of action. I am looking to order the service manuals and electrical diagrams to do some further testing.

 

If you look at #53 (system voltage too high 17.7 volts). The first thing I would check is the voltage. If it is that high it might have fried the ECM.

 

 

I just ordered the factory manuals. I will try to get to the ECM this weekend. I assume if the voltage is too high then I have an alternator/regulator issue. The truck was garaged for ten years and has had to have multiple jumpstarts (not all by me...) and several batteries since it sat for such a long time between runs. I wonder if a jump may have caused a surge. If the voltage is within range then I will change out the ECM, if not - then I need to get it down first. Thanks!

[Duelin]

It looks like nothing has changed. Funny thing is the codes won't even clear. The only code that cleared was 43. I am thinking the swap of the ECM may be the best course of action. I am looking to order the service manuals and electrical diagrams to do some further testing.

 

If you look at #53 (system voltage too high 17.7 volts). The first thing I would check is the voltage. If it is that high it might have fried the ECM.

[Duelin]

It looks like nothing has changed. Funny thing is the codes won't even clear. The only code that cleared was 43. I am thinking the swap of the ECM may be the best course of action. I am looking to order the service manuals and electrical diagrams to do some further testing.

 

If you look at #53 (system voltage too high 17.7 volts). The first thing I would check is the voltage. If it is that high it might have fried the ECM.

 

 

Not sure how I got a double post there. Must of stayed in memory or something. Sorry!

[jeffm5690]

It looks like nothing has changed. Funny thing is the codes won't even clear. The only code that cleared was 43. I am thinking the swap of the ECM may be the best course of action. I am looking to order the service manuals and electrical diagrams to do some further testing.

 

If you look at #53 (system voltage too high 17.7 volts). The first thing I would check is the voltage. If it is that high it might have fried the ECM.

 

 

Not sure how I got a double post there. Must of stayed in memory or something. Sorry!

 

 

Wouldn't a quick check of the voltage at the ECM fuse work?

[Duelin]

It looks like nothing has changed. Funny thing is the codes won't even clear. The only code that cleared was 43. I am thinking the swap of the ECM may be the best course of action. I am looking to order the service manuals and electrical diagrams to do some further testing.

 

If you look at #53 (system voltage too high 17.7 volts). The first thing I would check is the voltage. If it is that high it might have fried the ECM.

 

 

Not sure how I got a double post there. Must of stayed in memory or something. Sorry!

 

 

Wouldn't a quick check of the voltage at the ECM fuse work?

 

 

Check and see what the voltage is at the battery while the vehicle is running.

[jeffm5690]

OK - So I checked the voltage at the battery and ecm. I am getting about 14 at the battery and 13.6 at the ecm.

[jeffm5690]

I am about to scream. I go to put in a used ECM/PROM/CALPAK and then I see the heater core leaking. I replace that, put in the used parts and guess what... THE SAME CODES!!!! I am thinking that there must be a bad ground or some voltage issue. I think I need to take a step back and check out all the wires at the ECM harness for proper grounding, voltages and resistances from my GM Manual? I assume that would be the best course of action followed by checking all the sensors? I can't figure out why I get persistent codes telling me the ECM/PROM/CALPAK is bad... I also replaced the CTS and the code 14 is STILL there and I still have no change in the car temperature based on the dash gauge.

 

HELP!!!

[TJay74]

GM uses 2 temp ssensors, one to drive the dash gauge and 1 for the ECM.

[92rado]

Try and drive it for like 25- 50 miles and see if it reset it's self. That's always works for my truck after I disconnect the battery. I was told that the ECM has to collect information on all the sensors before it will reset completely

[jdaniel83]

Try and drive it for like 25- 50 miles and see if it reset it's self. That's always works for my truck after I disconnect the battery. I was told that the ECM has to collect information on all the sensors before it will reset completely

 

 

^^ What he said. My dad's 88 sat for about 2 yrs and once I got it running again it showed all kinds of codes. After driving it about 50 miles most of the codes didn't show back up.