98 Corvette BCM no comm
Thread Starter
1st Gear
Joined: Dec 2025
Posts: 1
Likes: 0
98 Corvette BCM no comm
I work by trade on circuit board repair and a friend of mine asked me to look at his 98 Corvette BCM. He is an Automotive teacher and one day a student hooked up positive and negative backwards. Upon finding it, he reversed the connections and everything is working besides the BCM so he asked me to take a look. On my initial check, I found that the 55199 transistor chip was hot in my thermal imaging camera. I replaced it and he said that it still doesn't work. I took another imagine and yes it is gradually rising in temperature but it is not as bad before. There are a few other hotspots but those are resistors so that is normal.
He explained to me that he checked all the grounds and that the BCM is receiving power. Just no communication from the scanner. It's definitely getting power since the IC and resistors are generating heat. I checked the relays on the PCB and they all are within spec and actuate as well. Does anybody have an idea on which IC check I should check and or any guides on with schematics?
He explained to me that he checked all the grounds and that the BCM is receiving power. Just no communication from the scanner. It's definitely getting power since the IC and resistors are generating heat. I checked the relays on the PCB and they all are within spec and actuate as well. Does anybody have an idea on which IC check I should check and or any guides on with schematics?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,191
Likes: 3,874
From: Cape Coral, Florida
For any "no comm" the FIRST thing to check is powers and grounds !!...looking at it is not the correct way as well as looking at done IC chips !!...you MUST load the powers and grounds to check them...a couple amp test light can be substituted as a load.
