Some good info on late model GM UART and Class 2

[sandrock]

http://tomboynton.com/GMnetworks.pdf

Some VERY good info here.

[harofreak00]

Awesome. Printed it and leaving in the bathroom for reading material

[swampthing]

just finished, very interesting read. I wish now so more then ever that I had a tech II.


I'll keep Pontiac Bonneville Club and angry birds for my bathroom :D

[harofreak00]

Read through a few pages, learning a lot.

Most of the newer cars nowadays have the center of this star topology wired into a connector (splice-pack), which had a removable "comb" which could be used to separate the serial lines for each module at a common point for easier diagnosis. The comb terminal connector would be removed from this connector and circuits could be jumped together to remove certain suspect modules from the rest.

I always wondered why GM was using splice packs like this... I guess they didn't anticipate water leaks and corrosion.

Automotive mechanics who didn't have a great knowledge of electronic systems would often guess incorrectly causing great unnecessary expense to the customer when "all three of his modules" were bad, when really it was just one of them or a wiring issue.

This is still happening. Had a customer a few weeks ago ask for 3 door modules. I thought that was kind of strangle, and I asked him about his symptons. He said that the passenger and rear windows/locks don't work. Luckily, I had just got through this problem myself weeks earlier, and I was able to repair his corroded serial bus line splice pack under the driver seat.