P167F — Transmission Control Module Internal Fault (P167F)

Diagnostic algorithm

1. Use an OEM-capable scan tool. Read and record P167F plus any other stored codes and freeze frame data.
2. Clear codes and attempt to reproduce. Note whether P167F returns immediately or after driving/cycle.
3. Verify battery state-of-charge and charging system. Ensure stable supply voltage with key ON and during cranking.
4. Visually inspect TCM connector, pins and harness for corrosion, water, damage or repairs. Repair any wiring faults.
5. Check fuses and power/ignition feed circuits to the TCM for continuity and proper voltage.
6. Verify ground(s) from the TCM to chassis/engine: clean and tighten connections, re-check continuity.
7. Check vehicle CAN/LIN communication: confirm other modules are communicating and no bus-short/termination faults exist. Use a scope if available to inspect for noise or missing frames.
8. If communication is intermittent or missing, isolate wiring harness or interchange connectors to locate short/open.
9. If wiring and supply/ground are good and communications healthy, check TCM software calibration level and compare to dealer service information for required updates or known issues/TSBs.
10. Attempt a controlled reflash or software update using OEM tools (follow manufacturer procedures and battery support). Do not attempt reprogramming if vehicle security/anti-theft procedures are unknown.
11. If reflash fails or fault persists after correct power, grounds and communications are confirmed, consider module replacement and program/configure new TCM per manufacturer procedures.
12. After any repair or reflash, clear codes and road test to confirm the issue is resolved, then re-scan for return of P167F.