Check Eng Light

[ToddG]

Here is a wierd one. When the car is running there is no check eng light. Car runs fine. Turn car off and remove key Chk eng light stays on and will not go off. Start car up light goes away...turn off remove key, light back on. I have tried disconecting the bat for 3o min or so to see if it world correct..no dice.
Any ideas??

Does anybody think this could have somthing to do with the earlier post with the problem of the t-top alarm switch?? I don't see how but you never know...
Thanks
ToddG

 

[DWncchs]

A few questions.
What does the light do when you turn the key to the ON position ?
You said twice to turn engine off and "remove key",do you really have to remove the key or does just turning the key to lock make the light come on ?
When doing the diagnostic test will the light flash the normal code 12 ?
Have you checked your "gauges" fuse ?

 

[ToddG]

light goes off when i start the car. turn car off the light comes on and stays on even when i take the key out. For the code how do i pull..is it like a dodge...of and on 3 times and then count?

thanks
toddg

 

[Twin_Turbo]

Is the light also on w/ engine off key to on pos?

The most likely issue would be that there's an issue w/ the ign witched power to the ECM and someone hooked it up to battery power. That way whenever you turn the engine off the std. code 12 trips because there's no crank signal (from EST) the system is designed like that but w/ RAM power hookedc up to BAT and system power to ign. switched. It's the pink/black wire:

 

[ToddG]

Is the light also on w/ engine off key to on pos?

engine off with key to on position...the light is out.

I have never had this problem before and no one has worked on the car. It just started today when i parked it at work.

just got back out from the garage...if i pull the the fuse for courtesy lights, of course the lamp goes out...but with the fuse out, i start the car and the CEL comes on (no fuse in) and stays on. This light seems to be running ass backwards. I am starting to wonder if the ignition switch itself is FUBAR

 

[Twin_Turbo]

Check the ground on the intake manifold pass side near the egr valve, that's the ecm ground, if that one is bad the light will do strange things

 

[ToddG]

Thanks for the diagrams. I checked the ground strap and it is fine.

on Sheet #3, what exactly does that " E CELL TIMER MODULE " do? The pink and black also run into that.

Thanks
ToddG

 

[big_G]

Is the light also on w/ engine off key to on pos?

engine off with key to on position...the light is out.

I have never had this problem before and no one has worked on the car. It just started today when i parked it at work.

just got back out from the garage...if i pull the the fuse for courtesy lights, of course the lamp goes out...but with the fuse out, i start the car and the CEL comes on (no fuse in) and stays on. This light seems to be running ass backwards. I am starting to wonder if the ignition switch itself is FUBAR

Look there first.

 

[JeffP1167]

Thanks for the diagrams. I checked the ground strap and it is fine.

on Sheet #3, what exactly does that " E CELL TIMER MODULE " do? The pink and black also run into that.

Thanks
ToddG

Has something to do with turning the light on at a mileage interval for some reason. I don't know what that reason is though, there is also a check engine light driver module kinda a rectangular looking tan colored box near the center console, I am not sure what year you vette is but I am pretty sure I saw it in my 82 vette and will try and get you a picture of it.

 

[TimAT]

The E CELL Timer looks to me like the time since last engine start. From a quick look anyway. Ckt 421 into the ECM connector B

 

[Twin_Turbo]

disregard the wiring diagrams, they are for an 82, I see you have an 81

the e cell timer is a module that alters the fuel ratio on the first so many miles during engine break in

 

[ToddG]

thanks for all the help and ideas. the problem has been solved. The culprit was the ECU (eng control module) switched it out and now everything is fine.

 

[MYBAD79]

:thumbs:

hope it was not too heavy on the wallet... these computer thingies are usually quiet expensive....

 

[ToddG]

The cost was 108 re-manufactured without the prom. Not bad.

c-ya
ToddG

 

[mrvette]

The cost was 108 re-manufactured without the prom. Not bad.

c-ya
ToddG

Which is why I have grabbed about 5 spare computers at ten bux each outta junkyards....my system is so old now, being a batch fire TPI from 20 years ago speed density system.....so I have spares I run the car on every once in a while....

:drink: