bulb is good , I have had the dash completely apart and can not get the check engine light to come on, even when trying to check codes, but the engine response to have the timing connector unpluged and timing set .thinking maybe the light driver module is bad. convertor isn't locking up unless i sort it out at the aldl connector under the dash. car seems to run fine
1989 caprice9C1 tbi 5.7

 

With my GM experiences, if my check engine light died, I'd celebrate...

 

An '89 Caprice will be using the 1228746 ECM. It drives the SES directly, no lamp module involved.

With both the TCC and SES not working I'd say the ECM has a fried quad driver. Driver U15 handles the SES, EGR, and TCC.

Pull the ECM, remove the 6 cover screws, look at the chips at the connector end of the PCB. There are 2 quad drivers that are in 16 pin DIP packages. See if one of them has physical damage to it.

I've seen them split in half, craters blown out of them, burned and melted looking. Usually the damage is obvious.

Then check the resistance of the EGR & TCC coils before putting another ECM in. Should be above 40 ohms in resistance.

RBob.

 

Thanks rob , thats a big help.

 

well opened it up and found the board around the u15 chip burnt looking , but the chip looked good on top , so i figure its fried,checked the tcc solinoid at the trans side of the plug and its reading .5 ohms. guess i'll get anouther solinoid an find a good ecm at the junk yard. egr solinoid was 60 ohms.

 

well just got back from the yard , found a perfect one from a 88 caprice broughm