TB1 - Diagnostic Trouble Codes 47, 633 and 691

Diagnostic Trouble Codes (DTC) 47 and 633 indicate the 4x4 Low Selector Lever is not in the 4x2 or 4x4 high position (observed in Key On Engine Off (KOEO) Self-Test). A change in the automatic transmission shift cycle will occur.

DTC 691 4x4 selector fault (observed in Continuous Self-Test) is set when a stored Keep Alive Memory (KAM) value for Engine RPM/Vehicle Speed (N/V) is compared to a calculated N/V for the current switch position and driving condition. It these checks disagree, DTC 691 is set.

Possible Causes:
- Damaged 4x4 Low switch or 4x4 selector lever position.
- Shorted harness.
- Damaged Powertrain Control Module (PCM).
- Internal damage to transfer case.

- Is the 4x4 lever positioned in 4x2/4x4 high?

Yes -- Go to TB4. TB4 - Cycle the Appropriate Circuit: (4X4 Low or Transmission)

No -- Rerun KOEO Self-Test with positioning selector in 4x2/4x4 high. Quick Test Appendix (Detailed Testing Instructions)