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Hello everyone, I've been working on my son's 1981 caddillac sedan deville for the past few months now. (whenever time permits) It has a 368c.i. with thottle body injection, multiple displacement(8-6-4cyl),H.E.I.,all factory except for a stereo system with c/d player. The problem I'm having with it is that is burning up E.C.M.s. It all started after I tried to diagnose a "check engine" light that was lit along with "temp" light,even though the engine was NOT overheating.After checking the basics,such as temp sending unit (switch) and wiring,I tried to retrieve trouble codes. Here's where I screwed up. :embarrass (yes I admit it) I looked under the dash and saw an A.L.D.L. connector,thinking if I grouded it, the "check engine" light will flash any trouble codes in the system,like other G.M. vehicles I've worked on.(After over 25yrs. of being a professional tech.,I should've known better.) The trouble codes on this car are retrieved through the A/C Heater controls.So it was at this point that I smoked the original E.C.M. I found a wiring diagram and tried to check pin voltages at the E.C.M.,as well as grounds.thought I found the problem,(3v cruise wire showed BATT.voltage) fixed it,replaced E.C.M.,only to burn it up too :( I can't seem to find any pin voltage charts for this car,and there isn't enough information in the schematics to figure out how much voltage I should have at E.C.M. pins. Can anyone help me in any way? Thanks
 

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I'm looking at a Chilton book for this vehicle but it does not include the 4,6,8 option or the fuel injection option.
All GM in 1981 used the CCC system. Check the emission sticker under the hood. I that what you have?

The procedure they describe calls for grounding the test terminal to view the trouble codes on the "check-engine-light".

Are you getting any trouble codes?

Will the engine run?

Looks like you have some other problem.

How do you know the ECM is bad?

vicrod
 
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