LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 37 (Automatic Transmission - ALLISON - Service, Diagnosis & Troubleshooting) >> Limp Home Mode >> Test Procedure

Test Procedure

WARNING: This page is about a different variant/trim than selected.

If a No Forward, No REVERSE, or Will Not Move condition occurs:

  1. Set the parking brake.
  2. With the ignition OFF, disconnect the 80-way connector at the transmission control module (TCM).
  3. Using a fused jumper wire to energize the neutral start relay, connect terminals 10 and 41 of the 80-way connector.
  4. Start the engine and move the range selector to REVERSE position.

    The transmission should engage REVERSE range.

  5. Move the range selector to the D position.

    The transmission should engage THIRD range.

If REVERSE and THIRD range are available in Limp Home Mode, an electrical failure may be indicated. If only 1 of the 2 ranges, or neither, was obtainable, this may indicate an internal hydraulic failure such as one of the following:

The clutches that could possibly have an indicated failure in Limp Home are the 1-2-3-4 clutch, the 3rd, 5th and reverse clutch, and the low and reverse clutch.