Well I got the SES light to work, I have a code of 43, which can mean a number of things,
"Poor electrical connection, (now that one's vague!) open or short in circuit (yeah, but what circuit?) defective ESC module, defective knock sensor, defective ECM"
I still have the occasional start it up, idle climbs to 1500, then as high as 3000.
IAC seems good, but something is telling it to speed the engine up. Disconnecting the battery naturally clears the codes. I have yet to check codes while this is occuring.
HOWEVER the light stays on all the time, no wonder the bulb and holder were missing, the used car creeps pulled it out.
Mr.Haynes manual also says if the light remains on all the time or I have a code 51 the PROM is not fully seated, is installed backwards, has bent pins or is defective.
So do I - A) just start throwing twenties at this thing
B) install a battery disconnect switch on the console to reset the ECM before my fiance has to slam it in gear at 3 grand when it does this crap
C) Isolate the cause by replacing the component MOST likely to cause this?

Sorry for the loooooong post!

Eric

 

It will stay on until the problem is fixed, then you reset the ECM(By removing the fuse for a number of minutes).

 

Hummm I would start with the cheaper and easier stuff first. Double check the conections at the ECM. Have your ESC checked out to make sur eit is not goffing up on you. Unless you want to drop some cash the last thing I would is go after the ECM and prom. All though a bad ECM may only be symptom of the problem. An ECM can be screwed up by other defective parts that send to much voltage to the ECM. So before just droping a new ECM you want to make sure you know why it went out. Old age, Bad sensor frying the line, ETC...

 

This is long.............

Make sure the knock sensor isn't disconnected and the wire isn't damaged. If you have a DVOM you can check the knock sensor itself. If you put one lead on the knock sensor and ground the other to the block it should read between 3300 and 4500 Ohms. If it's out of this range, replace it.

Also, with the key on, you should have a 4-6 volt reading at the knock sensor connector wire.
If less than 4, there is a open or short to ground in the circuit, or the ECM is bad.
If higher than 6, check for the knock sensor wire being too close to any plug wires, check for a short to voltage, or the ECM is bad.

Also check the knock sensor wire at the ECM for damage. It's on the YELLOW connector, a Dark Blue wire on the front row, 9th wire in. There will be a Dark Green/Yellow stripe wire on one side and another Dark Blue wire on the other side of it.

Check and see if the PROM is fully seated.

If circuit voltage is between 4-6 volts and sensor resistance is between 3300-4500 Ohms, and all the wires are OK and the PROM is seated, replace the PROM.

Also, with your wierd idle, the ECM might be suspect. If you're willing, try replacing the ECM and see if the code/idle probs go away. If they don't, throw the ECM back in the box, seal it up and return it.

 

You can put a 3.9k ohm resistor in place of the knock sensor. If you start the car and have no SES light anymore, the knock sensor was bad.

My dad's old '87 Oldsmobile 2.8 MPFI had a problem with the knock sensor. I repeatedly checked it out, checked the wire to the ECM, everything. I even replaced the old factory connector with a new one from Pep Boys. (Altho, the parts monkey behind the counter couldn't give me a part #; I had to look up a connector for an oil pressure switch, which was the same as the one-wire knock sensor connector.) Finally I followed Ed Maher's (tech board) suggestion of putting a 3.9k ohm resistor in it's place. I didn't have a 3.9k handy, so I used a 10k ohm potentiometer, and set it to 3.9k with my multimeter, and used that in place.

The SES light stayed on... the computer was fried. A new (okay, a junkyard) computer took care of it.

Oh yah- when the SES light would pop on, the idle would go to crap.

 

How do I check the ESC?
I don't have the car availible for me to work on right now, my fiance took it back to Viginia with her as it is HER car, and her LeBaron convertible puked the transmission .
Looks like I'll be working on that for awhile now!

Eric