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willysjeep [sm_search.gif]
AF Newbie
Joined: Mar 2005
03-13-2005, 07:55 AM
I had a similar problem on a '96 Blazer. After 70K miles 2nd going into 3rd gear on the automatic transmission was slipping. Check GM Bulletin Number 66-71-03A. The cause may be "poor internal ground between the two circuit baords of the VCM can cause the VCM to command erratic line pressure at the pressure control solenoid."
Basically, the control solenoid wasn't working correctly due to grounding issues and it caused the bands to slip, thus trashing my transmission.
If I were you, whether this is the cause of your problem or not, install the "Harness jumper wire and instruction kit P/N 12167310". It's a little jumper wire installed on the computer right under the hood. When you re-build your transmission you will want this fix or it may happen again. The kit costs about $10. If the jumper is already installed you should see a tag around the VCM wiring harness. I only wish my dealership at the time told me this. It would have been a small price to pay if I only would have known at the time.
If memory serves me correctly, I believe the manufacturer corrected this problem at the assembly line in March or April of 1996. I believe this problem existed since the transmission was put into production in 1995.
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Could be related, the "late 1995" blazers with OBD2 sometimes show up with problems that GM says started with 1996. A good solenoid might shift ok with a weak ground, but when the solenoid gets weak the problem shows up.