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Bonehead move with ecm?

equineman

Active member
Joined
Aug 10, 2007
Messages
29
Location
Marysville,In
Corvette
1981 Black coupe
So whats happens if you start the car with the jumper wire in the diagnostic port on the D and E terminals? I had no check engine light, so got new ecm put it in light came on. Tried to get codes after it ran for awhile. Light stayed on the whole time. Turned it off. Put jumper wire in. 105 heat index got me, lol. Started car. Light went out and won't come on agin? Please help. This forum rocks.
 
So whats happens if you start the car with the jumper wire in the diagnostic port on the D and E terminals? I had no check engine light, so got new ecm put it in light came on. Tried to get codes after it ran for awhile. Light stayed on the whole time. Turned it off. Put jumper wire in. 105 heat index got me, lol. Started car. Light went out and won't come on agin? Please help. This forum rocks.

Everything is in the normal operational mode? Turn Key to "Start" but don't startt eh car! No Idiot lights or just no "Check Engine"? You could have simply burned the bulb out - check that first - unfortunantly you will have be eithe A: double jointed and reach up behind the center console or do what I do and remove the seats, side panels, center console and then the gauge console - pain in the butt just to replace bulbs but I aint a spring chicken any more and can't bend that way! Oh an if you really want room to work - remove the seats. :D
 
Everything is in the normal operational mode? Turn Key to "Start" but don't startt eh car! No Idiot lights or just no "Check Engine"? You could have simply burned the bulb out - check that first - unfortunantly you will have be eithe A: double jointed and reach up behind the center console or do what I do and remove the seats, side panels, center console and then the gauge console - pain in the butt just to replace bulbs but I aint a spring chicken any more and can't bend that way! Oh an if you really want room to work - remove the seats. :D


Pull out the glove box. 8 screws. Reach around and change the lamp.
 
equineman ~ Welcome Aboard ~

Since the check engine light doesn't work, you question if you damaged the ECM... correct??

Without looking through the Shop Manual... Which I highly recommend each owner have (GM Shop Manual ST-364-91), I would suggest to take your car to a local garage or someone you know that can hook up the OBD reader and see if the ECM was damaged ;)

As IrishJoker says, it could be the light bulb decided to burn out, and he is right about getting at least the driver seat out then the side panel.. and if you have small arms and pretty flexable, you might be able to reach the Check Engine light with removing the center gauge console (which is a real pita to remove)..

Good Luck and let us know the outcome :upthumbs

Bud
 
When I turn the key to start I get the battery idiot light but no check engine light. I checked the bulb and fuse both are fine. Should the check engine light come on when the key is turned to start?
 
O'reillys is going to give me another ecm for free. So what are the steps to install ecm, and any special instructions after it's installed. Thanks for all your help. Going to be much cooler out tomorrow, lol.
 
I've never seen one. Whats it look like. Where does it mount?

O'reillys is going to give me another ecm for free. So what are the steps to install ecm, and any special instructions after it's installed. Thanks for all your help. Going to be much cooler out tomorrow, lol.
 
O'reillys is going to give me another ecm for free. So what are the steps to install ecm, and any special instructions after it's installed. Thanks for all your help. Going to be much cooler out tomorrow, lol.

Just follow the instructions with the unit. Follow "static" protocol when transfering the prom. You have to remove the battery to change it . I take the top off to help get in there.:)
 
New ecm gives check engine light but will not give codes. When I do ground out D and E all I get is the choke light coming on.
 
New ecm gives check engine light but will not give codes. When I do ground out D and E all I get is the choke light coming on.

:ugh Wow. You definetely have a wiring problem. I have never heard of that one.
 
Take it out for about an hour drive or so, then check for codes. If you don't get any codes I'd suggest to disconnect the battery for a few seconds then reconnect and go for another drive.

Maybe you need to give the ECM some input and see if functions and makes corrections or flips a few codes ;)

Bud
 
The choke is not controlled by the ECM. The only commonality here is the engine and ECM grounds. Start there.;)
 
where is the ecm ground?

Okay. Two places to check(That I know of). Engine ground. Pass side, block to frame. This one is rather large.
Front of carb. There are two wires to the M/C , pass side, a green clip for testing dwell, and a ground wire to the carb. It should be black.
 
I have found out that the E terminal is the ground. I happen to have 11.72 volts running thru mine. On the D terminal I have about .72 volts. Any idea what the correct values are?
 
I have found out that the E terminal is the ground. I happen to have 11.72 volts running thru mine. On the D terminal I have about .72 volts. Any idea what the correct values are?

A-Carb sol. (same as green test lead)

B-Check engine light

C-Air control (Diverter valve)

D-Diagnostic enable

E-Chasis ground

I do not know the value of D. I am quite sure it is 2volts or less
 
I have found out that the E terminal is the ground. I happen to have 11.72 volts running thru mine. On the D terminal I have about .72 volts. Any idea what the correct values are?
I think you are reading pin A and B

Okay, from a Snap-on Scanner book.

Connect pos. lead of voltmeter to pin E, (far left), connect neg. lead to batt - term. Should read .1 volt or less
To test for open ground, jumper D to E, then reread voltage. Should read 50 millivolts. If 5 volts, ground is open.
Pin D should read 5 volts to ground. Pin B should read .7 volts to ground This voltage will rise when engine is running and check engine light goes out.

Important. The pins are ABCDE, right to left as viewed thru the ashtray. You will see a notch between D and E.
 

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