TCM Power Relay Sense Circuit High

What it means

P0891 is stored when the engine control module measures a voltage in the TCM Power Relay Sense circuit above the expected maximum, typically because the signal wire is shorted to battery voltage or the circuit is open and pulled up internally.

This entry is compiled automatically from the standard definition and typical diagnostic practice for this type of fault. A detailed, reviewed article is in preparation.

Symptoms

• Check engine or transmission warning light
• Harsh, delayed or missing shifts
• Transmission stuck in one gear (limp mode)
• Shuddering or slipping under load

Common causes

1. Damaged, chafed or corroded wiring in the TCM Power Relay Sense circuit
2. Corroded, loose or water-damaged connector terminals
3. Failed TCM Power Relay Sense component (sensor, solenoid or actuator)
4. Poor ground connection for the module or component
5. Faulty control module driver (rare, confirm all else first)

How to diagnose

1. Read freeze frame data and note when the code set (cold start, under load, after rain)
2. Inspect the TCM Power Relay Sense connector for bent pins, corrosion and water; wiggle the harness with the engine running and watch live data
3. Measure supply voltage and ground at the connector with the key on
4. Check the signal wire for shorts to ground or battery and for continuity to the control module
5. Test or substitute the TCM Power Relay Sense only after wiring and connectors are confirmed good
6. Clear the code and complete a drive cycle to confirm the repair

Related codes

Nearby codes in this group

• P0890TCM Power Relay Sense Circuit Low
• P0892TCM Power Relay Sense Circuit Intermittent
• P0889TCM Power Relay Sense Circuit Range/Performance
• P0893Multiple Gears Engaged
• P0888TCM Power Relay Sense Circuit
• P0894Transmission Component Slipping
• P0887TCM Power Relay Control Circuit High
• P0895Shift Time Too Short