Codes

[Nut]

Well I've searched high and low through the reams of my documentation and I have lost/misplaced by list of "Check Engine" codes and which two pins to short to dump the codes. Any help w/b greatly appreciated. I suspect an O2 sensor (since that's about all that's left of the Emissions stuff I haven't ripped off.

Thanks in advance.............. Bob (Nut)

 

[Yoda]

Oh Nut what are we going to do with you

The terminal is under the ashtray, short "D" & "E" the CHECK ENGINE light shoud begin to flash a Trouble Code 12. This is from the GM Shop Manual:

Code 12 consists of one flash, a short pause, then two flashes. There will be a longer pause and Code 12 will repeat two more times. This check indicates that the self-diagnostic system is working. The cycle will then repeat itself until the engine is started or the ignition is turned "OFF." If more than one fault is stored in memory, the lowest number code will flash three times followed by the next highest code number, until all faults have been flashed. The faults will then repeat in the same order. Remove ground from terminal "D" (test terminal) BEFORE STARTING ENGINE!

Trouble Code 13 is the oxygen Sensor Circuit. The engine must run up to five minutes at part throttle, under road load, before this code will set.

Nut if you come up with other codes let me know and I'll look them up for ya

Bud

 

[Nut]

Thanks Bud. I knew where the connector was. I'll dump the codes Sunday and let you know what else pops up.

Later............ Nut

 

[Vader]

'81s are pretty simple controls:

The ALDL connector is under the center console ash tray.

Code #12: No Distributor Reference Pulse.
Code #13: Oxygen Sensor Circuit.
Code #14: Shorted Coolant Sensor Circuit.
Code #15: Open Coolant Sensor Circuit.
Code #21: Throttle Position Sensor Circuit.
Code #23: Mixture Control Solenoid Circuit.
Code #24: Vehicle Speed Sensor Circuit:
Code #32: Baro Sensor Circuit Low.
Code #34: Vacuum Map Sensor Circuit.
Code #44: Oxygen Sensor Lean.
Code #45: Oxygen Sensor Rich.
Code #51: Faulty or Mis-Installed PROM (Checksum)
Code #52: Faulty ECM (I/O Scan)
Code #53: Faulty ECM
Code #54: Shorted Mixture Control Solenoid.
Code #55: Faulty Oxygen Sensor or ECM.

Later,
Vader
__________________
1911A (Series VII) .45 ACP

 

[Yoda]

Add Code #42

Code #42 Electronic spark timing (EST) bypass circuit grounded. Completes the list. Nice job Vader

 

[Vader]

OOPS!

(Missed that one!)

And the '42' carried all the way through the later ECMs 'til 1992. You'd think I woulda caught that.

As long as you're in here, any idea if there is a ROM mask or code for the E4ME ECM used on the '80 CAFE and '81 Federal cars? I do a little PROM burning for later cars (mainly TPIs) and would like to hack into the '81 to see if I can alter TCC, P/E, and the spark tables. It would be a nice "quick-and-dirty" plug in for a lot of '81 owners who still suffer with the factory settings and don't want to retrofit a newer ECM. That would be a custom harness for sure just because of the location. Even a relatively simple TBI ECM would be a weeks worth of wiring.

I'm going to dump the PROM to a binary file and hack in anyway to see if I can find anything familiar, but a mask would make life so much easier. Once one is tuned and done, burning more PROMs is a 20-second task for anyone with a spare (finding spare 2708 PROMs just ain't that eaqsy any more....).

 

[Yoda]

Vader... You are so far over my head I got lost before I finished the first paragraph :confused.. I'm not that profecient with computerized cars, thus after a few C4's I went back to the '81, even though it has a very basic computer..

The CA 1980's were all automatics with 305 cid and the same basic computer was used in 1980 and became standard in all 1981's.

Sorry I won't be much help, if I can't put a screw driver or wrench on it I get lost fast

Bud

 

[Vader]

Thanks. It seems that sometimes the best "fix" for an unreliable ECM is indeed to put a screwdriver or wrench on it...

If I find something that works, I'll be back with info.

 

[Nut]

You guys are the best. Since it's a deluge today I will be dumping codes today. Results soon.

Thanks Bud and Vader, I'll have them laminated on Monday and glued to the wall.

.......... Nut

 

[Vader]

BTW - Nice...umm...dog? you've got there.

 

[Nut]

Vader.... I'm not quite sure what it is. It was sent to me by a friend in Tasmania. My guess is it's a hairless and PO'd looking Kangaroo. Could be a dog? Could be a cat?

............. Nut

 

[Mr. Chuck]

GM Chevy Shop Manual, Sect / Page 6E1-8 gives step by step direction on how to get the Check Eng codes and how to read them. A brief description follows:
1. Locate 5 pin, single row connector under the ash tray (pull Tray out).
2. With the igniton turned on & eng stopped, the check eng light should be on ( a blub check).
3. The connect is labeled "A" - "E", from left to right. Jumper the far right hand two pins together will cause the check eng light to flash out the 2 digit error codes stored in the Electronic control modual (ECM). The "D" pin is the test contact and pin "E" is Ground.
4. Do not start engine with the jumper in place.
5. The Error code displayed begins with the lowest error code stored; the first digit count by the number of flashes of the check eng light, a short pause and the second digit of the error is displayed. Each error code is flashed three times seperated by a little longer pause, before any additional stored error codes are flashed. each errors code stored will be display 3 times in sequence.
6. Code "12" flashes signifying the self dignostic system id working!
7, Subsequent error codes and related trouble shooting procedures are defined in subsequent pages of the shop manual and too detailed to list here. A brief definitions of each trouble code (TC) follows:
8. TC13 Oxygen Sensor, TC14 Shorted coolant sensor, TC15 Open coolant sensor, TC 21 Thorttle sensor, TC23 Open or grounded M/C soleniod, TC 24 Speed sensor, TC 34 Vacuum sensor, TC 42 Electronic spark timing bypass grounded, TC 44 & 45 at same time Faulty oxygen sensor circuit, TC 45 only Rich System indication,TC 51 Faulty Calibration unit, TC 52 Faulty ECM, TC53 Faulty ECM, TC 54 Shorted M/C solenoid circuit, & TC55 Groundedd +8volts, Vref, faulty oxygen sensor or ECM.

Bottom line is look for someone close by with a shop manual or a friendly dealer who can provide access to the trouble shoting procedures defined in the GM shop manual

**** Don't forget, Remove jumper before starting engine! ****

ps: I purchased the shop manual shortly after buying the car.

Regards:

 

[xlr8shn]

Check engine light on my 81 is lit.

I followed above instructions jumping the far right two terminals below the ashtray while ignition in accessory position (car NOT running)... Nothing happens, light stays solid and no blinking of the codes.

What is next thing to check?

THANKS!

 

[smithjw]

I'm not so sure you can have the ignition in the accessory position to do the test. I think you need to turn the key in the other direction one position away from actually having the starter kick in.

 

[xlr8shn]

I'm not so sure you can have the ignition in the accessory position to do the test. I think you need to turn the key in the other direction one position away from actually having the starter kick in.

I'll check for another position with the ignition key. Guess I need to see if there's another position there before the car turns over.

THANKS!