SureTrack Community Fix: Lockup Issues After Rebuild

Real Fixes from Mitchell 1’s SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read on to see how SureTrack can help you correct issues that are not easily diagnosed using OEM information alone. SureTrack is available at no additional cost in our ProDemand product.

Nothing is more frustrating than going through an extensive repair and then not have the vehicle operate as it should. Fortunately the SureTrack Community is here to come to the rescue. SureTrack community member DAREAUTO had a 2007 Hummer in the shop for a transmission rebuild and when they were done it wasn’t going into lockup as it should. They posed the question to the community, and with the help of fellow community member MIKE1968 and others, they were able to resolve the issue quickly.

The following Community Fix summarizes the interaction between members of the community that led to the solution.

2007 Hummer H3 3.7L

Transmission not going into lockup every time, install fuses.

Transmission not going into lockup every time after rebuild and flash of PCM.

Diagnostic Steps Performed/Parts Replaced
Rebuilt transmission, replaced torque converter, TCC solenoids and wiring harness. Used master kit with seals, gaskets and clutches, bored the valve body per update and updated springs. No codes.

Best Answer from Community Member MIKE1968
Like ericsautomotive stated, look for any PIDs that are associated with TCC lockup. Such as ECT, TPS, TCC, BPP, APP, etc. There may be something outside of the transmission causing this issue.

Checked the brake switch, then went to fuse box found missing fuses for brake switch, cruise control and SDARS (Satellite Digital Audio Radio System).

Installed the appropriate fuses and that fixed the problem. Transmission operates properly. Thanks guys for heading in the right direction.

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About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.