Intermittent Code 32 and hot ECM-B fuse

[Robert Mitchell]

Hello. I have a 1989 Suburban. 5.7 2WD. Automatic transmission with OD 784K miles.

Started out with throwing an intermittent code 32: EGR MAP fault. Changed all the related accessories. (EGR valve and solenoid. Map sensor, Water temp sensor, throttle position sensor) This did not fix the problem.

As time passed. Check engine light / Code 32 would intermittently show up after engine was fully warmed up. It will usually, but not always appears at idle and vanishes when RPM is increased.

Recently. Check engine light would intermittently turn on when you activate the brake petal switch. Or, light would intermittently flash when you manually shifted from drive to OD and back.

After troubleshooting with a IR camera, I discovered that the ECM-B fuse runs very hot while engine is running. Nothing else accessible appears to be unusually warm with the accessible areas of the wiring harnesses. Not sure what the ECM-B would have to do with it but.........

Any good ideas would be appreciated. Thank you.

Edited April 18, 2022 by Robert Mitchell