My "Check Engine Light" is on in my '92 GXE. The engine is barely running, so I want to read the codes from the ECU.

I followed the instructions i had describing how to do this ((turn IGN on, turn screw, look at red/green LED's)) , but the ECU won't display the codes! The red LED stays on solid - never blinks, and the green one never lights...

Can someone outline the correct way to get the ECU to display codes!?!?



Any help is greatly appreciated...


Thanks!!

 

Turn the screw clockwise and wait for the lights to flash 3 times. Once it flashes 3 times turn it back counter clockwise and you will be in mode 3 which is the diagnostics mode. The codes are as follows:

On the numbers, the first number is a red light the second is a green say for instance you have 31, it's 3 red flashes 1 green flash.

The explanation of the codes are listed at the bottom.

Code 11 - Crank angle sensor/circuit
Code 12 - Air flow meter/circuit
Code 13 - Cylinder head temperature sensor
Code 14 - Vehicle speed sensor
Code 21 - Ignition signal
Code 22 - Fuel pump circuit
Code 23 - Throttle valve switch circuit
Code 31 - ECU control unit
Code 32 - EGR Function (1989 Cali models only)
Code 33 - Exhaust gas sensor
Code 34 - Detonation sensor (1989 models)
Code 43 - Throttle sensor (1989 models)
Code 45 - Injector leak (1989 Cali models only)
Code 54 - A/T control unit (1989 models)
Code 55 - ECCS

Code 11 - Check the crank angle sensor and replace

Code 12 - The air flow meter source of ground circuit(s) may be shorted or open. Check the air flow meter.

Code 13 - The sensor source or ground circuit(s) may be shorted or open. Check the temperature sensor/circuit(s)

Code 14 - The vehicle speed sensor signal circuit is open. This repair must be performed by a dealer service department (now known as dsd) (the speed sensor is an easy fix unless they are talking about somehow breaking it open and fixing the internals)

Code 21 - The ignition signal in the primary circuit is not entered during engine cranking or running. This repair must be performed by a dsd.

Code 22 - The fuel circuit is open or shorted.

Code 23 - The throttle valve switch signal circuit is open.

Code 31 - The ECu input signal is beyond "normal" operating range. This repair must be performed by a dsd.

Code 32 - The EGR control valve does not operate.

Code 33 - The exhaust gas sensor circuit is open.

Code 34 - The detonation sensor circuit is open or shorted. This repair must be done by a dsd.

Code 43 - The throttle sensor circuit is open or shorted. This repair must be done by a dsd.

Code 45 - The injecotr(s) have fuel leaks.

Code 54 - There is a short between the A/T Conrtol unit and the ECU. This repair must be performed by a dsd.

Code 55 - "Normal" operation.

 

Thanks for the reply!

That's pretty much the procedure I was following, but the lights never blinked.

How long do I have to wait after i turn the screw?

Should the IGN be ON?

How do i reset the codes?

 

ignition should be in the on position but the car shouldn't be on to my knowledge. once you turn the screw clockwise it should start flashing lights and once it flashes 3 times you can turn it counter clockwise. to reset the codes go into mode 4 (4 flashes) and then shut the key off. i believe you have to wait 10 seconds before turning the key back on or something like that.

 

I dont know about you guys, but there is no green light on mine, I Know the procedure in some places say green light, but not for the 3rd gens.

Turn ignition key to ON position
turn screw fully clockwise
wait at least 3 seconds
turn scre fully conterclockwise
red LED will flash X number of times LONG, then Y number of times short.

XY is your code as described in previous post above.

To get out of this mode, turn screw fully clockwise again for 3 seconds and back again. Turn ignition key off.

 

Can you think of any reason that this wouldn't occur??

The Red LED is always on solid - I turn the screw clockwise all the way, then nothing.... the red LED stays on and the green never comes on.

 

He described the procedure wrong, please read my above post...

 

Ok - I'll have to try it that way. There do appear to be 2 LED's (1 red, 1 green) on my ECU, though - - is the green inactive?

How do I reset the codes?

 

what year max do you have? i know for sure that there is a green and red light on the 89-91. i don't know about the 92-94 but i would think at the least they would stay the same for the 92-94 gxe's.

to clear the memory you can go to mode 4 and then turn the key to the off position or you can leave the battery unplugged for something like, 24 hours.

 

Mine's a '92 GXE...

 

it should be the same then. are you fully turning the screw clockwise (all of the way until it stops)? that could be the only thing i could think of that is keeping the red light on and it not going into the dianostics menu.

 

oh yeah - I even put a bit of force into it....


btw... do these cars have a sort of "Limp-Home-Mode" ?
For instance, say the owner of the car did something stupid, like disconnect the intake hose between the MAF and the Throttle Body. Then, let's say the owner went and drove the car down the road, and it pretty much died... This guy (*cough* *cough*) then notices that the CEL comes on and he can drive the car home SLOWLY using VERY gentle throttle inputs...

The moron owner then re-connects the intake hose, but the engine still runs crappy and the CEL is still on... If he resets the ECU, will it once again try to run the engine normally??

 

yeah, our ecu's do have a limp home mode. when in that mode it won't rev past 2000 rpm i believe and it runs very rich. if you reset the ecu it should go back to normal.

 

that sounds consistent with what I'm experiencing!

maybe the car is already fixed and I just need to reset the codes!!

 

try keeping the battery unplugged for a day. that's supposed to reset the ecu.

 

I'll give it a shot and let you know what happens!!

Thanks again for all the help!