reg_255

Hi C4 Gurus,

I bought a 1992 at an auction that was in rough shape.
With much help from a friend, we replaced the following.
Spark plugs and Wires
Optispark (with a Petris vented Optispark)
Water pump (Delco)
Associated coolant hoses.
Flushed Radiator and Heater Core.
It still runs badly, bought a OBD1 Scan tool.
Here are the Current codes.
Is there one area to focus on that will address some of these?
Or sell it and cut my losses?

All constructive help is greatly appreciated.

92ragtop

This 1992 code chart is a bit easier to understand. Either way, it sounds like you've got multiple issues. Clear the codes, and then see if the same ones come up again.
Hopefully some of the diagnostic gurus here will chime in to help out. A Factory Service Manual will be a big help.



92-93 5.7L VIN P
13 Oxygen sensor voltage stays between 0.35 and 0.55 volts for 60 seconds. Engine was at normal operating temperature and had been running for at least 2 minutes after start with a throttle angle above 5%.
14 Coolant temperature sensor signal indicates a temperature of over 266? F.
15 Coolant temperature sensor signal indicates a temperature colder than -56? F.
16 A low resolution pulse was not detected by ECM within 720 high resolution timing pulses.
21 TPS voltage was above 2.5 volts for 3 seconds when the engine was running, or when the TPS was above 4.8 volts at any time.
22 TPS voltage was under 0.23 volts when the engine was running.
23 Inlet air temperature sensor signal showed an air temperature below -31? F for 60 seconds after the engine has been running for 4 minutes.
24 Vehicle speed was 0 MPH when engine speed was between 900 and 3000 RPM and throttle position angle was less than 2% for 5 seconds.
25 Inlet air temperature sensor signal showed an air temperature over 302? F for 12 seconds after the engine has been running for 4 minutes.
26 ECM detected the wrong potential voltage at the #1 quad-driver module circuit for 20 seconds.
27 ECM detected the wrong potential voltage at the #2 quad-driver module circuit for 3 seconds.
28 ECM detected the wrong potential voltage at the #3 quad-driver module circuit for 3 seconds.
32 EGR open command did not change the fuel mixture when the command was given during off idle operation. EGR opening should cause the mixture to be slightly richer because of the low oxygen content of the exhaust gas.
33 MAP sensor signal voltage was too high (low vacuum) for 1 second when throttle opening was under 3% and engine speed was above 500 RPM.
34 MAP sensor signal voltage was too low (high vacuum) when engine speed was under 700 RPM, or when TPS was greater than 20% with an engine speed above 700 RPM.
36 ECM detected less than 60 high resolution timing pulses between each low resolution pulse for 5 consecutive cycles.
41 EST circuit voltage was above 4.6 volts when engine speed was under 1500 RPM.
42 The EST circuit voltage was below 0.5 volts when engine speed was below 3000 RPM.
43 One or both of the knock sensors were either open or grounded for 5 seconds.
44 Left oxygen sensor voltage was under 0.2 volts for 50 seconds of closed loop operation.
45 Left oxygen sensor voltage was over 0.7 volts for 50 seconds when the throttle angle was above 4% during closed loop operation.
51 PROM error. (Means PCM problem)
52 Engine oil temperature was below -31? F after engine had been running for 30 minutes.
53 ECM detected a battery voltage either above 17.1 volts or below 8 volts.
55 ECM detected a lean oxygen sensor voltage for 3 seconds during the power enrichment modes of operation.
62 Engine oil temperature sensor indicated an oil temperature above 284? F after engine had been running for 30 minutes.
63 Right oxygen sensor was open showing a steady voltage between 0.35 and 0.55 volts for 60 seconds after the engine had been running for at least 2 minutes.
64 Right oxygen sensor voltage was below 0.2 volts for 50 seconds of closed loop operation.
65 Right oxygen sensor voltage was above 0.7 volts for 50 seconds of closed loop operation when the throttle angle was above 4%.
66 A/C pressure sensor circuit was either open or shorted showing a voltage below 0.12 volts or above 4.86 volts for 10 seconds.
67 ECM did not detect an A/C system pressure change of more than 9 psi when A/C clutch was engaged.
68 ECM detects voltage on the A/C status line for more than 20 seconds after ECM has disengaged the A/C relay.
69 ECM did not detect any voltage on A/C status line for 20 seconds after ECM had commanded A/C ON.
72 2nd or 3rd gear switch was open for 1.5 seconds when vehicle speed was above 30 MPH with engine speed greater than 5000 RPM and a throttle angle above 70%.

Patsgarage

I agree with 92ragtop. You need to clear all the old codes and see which ones come back up. Depending on the scanner you have you can either use that to clear the codes (most scanners cannot do this) or disconnect the battery to reset the computer. I think there is a quicker way as well, but it is slipping my mind at the moment. Good luck, and keep us posted on what codes come back up.

reg_255

It does not appear that OBD1 codes can be cleared from the Scanner.
I disconnected the battery for a couple of mins are reran the Scan.
The Scanner indicates these are all Current codes.
They all returned in addition to a Code 41.
I guessing except for the A/C codes these are all related to a faulty ECM.
Any suggestions on a reliable reasonably priced place to get it reconditioned?
My wife has been unemployed for 2 years and has had enough of me trying to get my bucket list car on the road.

Patsgarage

Humor me and leave the battery disconnected overnight. I just can't believe that all of those codes are current ones. It is possible, but they point in so many different directions that I just can't believe it. If the ECM was that fried the car would nor run at all. I picked up an ECM for a Cobalt on Ebay last year, maybe check there first.

Dt86

I had a similar issue and it was the ECM. Also had a severed ground strap. https://www.corvetteforum.com/forums...-paradise.html

reg_255

Hi all,

I will disconnect the battery for a few days to see if the conditions change. Probably won't be able to get to it until the weekend.

Will also look for any issues with the grounding.

I appreciate all your interest in helping.

Regards,
Roy

92ragtop

1992 ECM's are hard to find. I had mine fixed by Davies Corvette in FLA, and it's been fine since.

Cliff Harris

You have too many codes for them to be legitimate. Either the scan tool is not configured correctly or you have major ground issues. I would guess the prior.

Pull the codes using the paperclip method:

http://forums.corvetteforum.com/1574918379-post18.html
http://corvettephotographs.com/c4vettes/codes.htm

You won't have any configuration or interface issues if you do it this way.

reg_255

I had the negative battery cable disconnected since Tuesday.
Reconnected the battery, connected the Scanner.
It took several tries before the reader would communicate with the ECM.

The results are similar to the last check. I've not had a chance to check the ground yet.

So best guess, the ECM is toast?

Cliff Harris

ECMs are pretty robust. It's hard to damage one.

As i said in post #9, pull the codes with the paperclip method so you won't have any issues with the scan tool interfacing with the ECM.

John A. Marker

Try this to clear the codes The codes are displayed in the center of the speedometer display.

Clearing the CCM codes can be done after the automatic sequence of codes has occurred with the following instructions:

Press the TRIP RESET button until “1.0” is displayed in the module number area. Then press the TRIP/ODO button until “1.7” is displayed in the module number area. Once there, press and hold the ENG/MET button until “—“is displayed. This will clear any CCM codes. After “—“ is displayed, turn the key off, wait ten seconds, turn the key back on and check for any CCM codes.
Press the TRIP RESET button until 4.0 is displayed in the module number area. Then press the TRIP/ODO button until 4.7 is displayed in the module number area. Press and hold the ENG/MET button until “—“ is displayed. This will clear any ECM codes. After “—“ is displayed turn the key off, wait ten seconds turn the key back on and check for any ECM codes.

ABS/ASR EBTCM

Press the TRIP RESET button until 9.0 is displayed in the module number area. Press the TRIP/ODO button until “9.7” is displayed in the module number area. Press and hold the ENG/MET button until “—“ is displayed. This will clear any ABS/ASR codes. after “—“ is displayed, turn the key off, wait ten seconds, turn the key back on and check for any ABS/ASR codes.
- See more at: http://tech.corvettecentral.com/2011....YZ7tYvF9.dpuf

rocco16

After looking at all the codes, a bad ground (or grounds) was the first thing that came to my mind.

reg_255

I will check the grounds, need to wait for the weather to warm up a bit.
Going to be cold this weekend.

reg_255

Hello All,

It's been awhile since my last post do to a broken Heel bone.

The battery has been disconnect since Feb. and has been keep charged.

I checked the codes before starting, saw H72 H15 H16.
Ran the engine for a few minuets and drove it around the block.
Have the Service Engine Soon and only the Historical codes.

Any suggestions on how to determine what is causing the S.E.S. light?

My first thought is to replace the O2 sensors.

Thanks,
Roy

VikingTrad3r

just joining the thread now but id be following the advice of the boys here and checking (cleaning and retightening) all grounds for your year.

i found a diagram in another forum thread that should give you a start.

hope your situation has changed and your is onboard with your car. good luck!

reg_255

Hey All,

I cleared and verified all codes were cleared.
Started the car let it run for awhile.

Rechecked the codes, no current alarms.
Codes that are displayed, H15, H16, and Service Engine Soon.

Also noted the digital temperature gauge seems to stop at 142 degrees.

Things that have been replaced in the last 3 months.
Spark plugs
Plug wires
Vented Optispark (Petris)
Water pump
Analog Coolant temp sensor.
Drive belt
Flushed Radiator
Had ECM tested (no trouble found)

Any help with isolation of the codes / SES is greatly appreciated.

Thanks,
Roy

Patsgarage

Glad to hear that you are back on your feet again. Just to clarify the current codes are only the 15 & 16 ones, right ?

VikingTrad3r

order a new coolant temp sensor from rock auto. these c4's are like a game of whack a mole.

U smash one issue and another rises up. over and over.

But then u see the light at the end of the tunnel.....

I do it cheap so the guilt doesnt kill me. But my point is, if u notice your coolant temp sensor is failed, dont hesitate just order it.

There is probably a test to verify if its the sensor or if it is the dash failing but ill guess the sensor if everything else is reading correct.

the coolant sensor being out of whack can really mess up the smooth operation of the cars systems.

edit: i see u replaced a sensor already for temp. maybe the lcd dash?

reg_255

Hey Patsgarage,

Thanks for the well wishes.
Sucks being 3/4 plus age down for 3+ months .

To calcify the only time I see H15, H16 is after running the car.

I cleared the codes from the ECM


Patsgarage,

Going to spend the few dollars and get a new sensor, not worth my time if it fixes it.
If not I have one less thing to give me grief .

Thanks,
Roy