Shift/Timing Solenoid Low

What it means

P0787 is stored when the engine control module measures a voltage in the Shift/Timing Solenoid circuit that stays below the expected minimum. In practice this points to a short to ground, a damaged wire or a failed component rather than a mechanical problem.

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 Shift/Timing Solenoid circuit
2. Corroded, loose or water-damaged connector terminals
3. Failed Shift/Timing Solenoid 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 Shift/Timing Solenoid 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 Shift/Timing Solenoid 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

• P0786Shift/Timing Solenoid Range/Performance
• P0788Shift/Timing Solenoid High
• P0785Shift/Timing Solenoid
• P0789Shift/Timing Solenoid Intermittent
• P07844-5 Shift
• P0790Normal/Performance Switch Circuit
• P07833-4 Shift
• P0791Intermediate Shaft Speed Sensor 'A' Circuit