OBD2 P0837

Severity

Summary

P0837 indicates a problem with the four-wheel drive (4WD) switch or its control circuit on vehicles equipped with electronically controlled AWD or 4WD systems.

Symptoms

• Stored trouble code and possibly an illuminated warning light
• One or more drive train modes may fail to engage or disengage
• On automatic transmissions, shifting may be harsh, erratic, or the transmission may not shift at all
• In rare cases, mechanical failure of the transfer case may occur

Common Causes

• Defective four-wheel drive selector switch
• Damaged, burnt, shorted, or corroded wiring and/or connectors
• Mechanical failure of drive train components (rare)
• Failed or failing PCM (rare)

Diagnosis

1. Check for additional codes and their relationship with P0837.
2. Inspect the four-wheel drive selector switch for visible damage.
3. Verify reference voltage at the PCM connector.
4. Test signal voltages for each position of the switch.
5. Perform a thorough visual inspection of all associated wiring.
6. Conduct resistance, continuity, and ground integrity checks on wiring.

Fixes

• Replace the four-wheel drive selector switch
• Repair or replace damaged wiring and connectors

FAQ