Shift Timing Solenoid B Intermittent
The P078E code indicates that the transmission control module (TCM) has detected an intermittent fault in the shift timing solenoid B circuit. This solenoid is responsible for regulating hydraulic pressure to control shift timing in automatic transmissions. An intermittent signal suggests a loose connection, wiring damage, or internal solenoid failure, leading to erratic shifting behavior.
01. Most Common Causes
- Faulty shift timing solenoid B
- Damaged wiring or connectors in the solenoid circuit
- Low transmission fluid level or contaminated fluid
- Internal transmission mechanical issues
02. Symptoms You Will Notice
- Erratic or harsh shifting
- Delayed engagement when shifting into gear
- Transmission slipping between gears
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect transmission fluid level and condition; top off or replace if necessary.
Step 3: Visually check wiring and connectors to solenoid B for damage, corrosion, or loose pins.
Step 4: Test solenoid B resistance and operation using a multimeter and scan tool.
Step 5: If solenoid and wiring are okay, perform a transmission pressure test to rule out internal issues.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as intermittent shifting can lead to transmission damage. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, depending on whether the solenoid alone needs replacement or if wiring repairs are needed.