Clutch Switch Circuit Malfunction (P0704)
The P0704 code indicates a malfunction in the clutch switch input circuit. In Ford F650-F750 trucks with an Allison AT545 transmission, this code may also refer to the neutral safety switch circuit. The PCM detects an incorrect voltage signal from the clutch pedal position sensor or neutral switch, often due to a faulty switch, wiring issues, or misadjustment.
01. Most Common Causes
- Faulty clutch pedal position switch
- Open or shorted wiring in the clutch switch circuit
- Misadjusted clutch switch
- Faulty neutral safety switch (Allison AT545)
- Corroded or loose electrical connectors
02. Symptoms You Will Notice
- Engine may not start or starts only in neutral
- Cruise control inoperative
- Check Engine Light illuminated
- Transmission shifting issues
- Stalling when clutch is depressed
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and verify P0704 is present.
Step 2: Visually inspect the clutch switch and wiring for damage or corrosion.
Step 3: Test the clutch switch operation with a multimeter; check for continuity when pedal is pressed.
Step 4: Check switch adjustment; ensure it actuates properly at the correct pedal position.
Step 5: For Allison AT545, test the neutral safety switch circuit and adjust or replace as needed.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It may be safe for short distances, but driving is not recommended as it can cause stalling, no-start conditions, or transmission issues. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs typically range from $50 to $150 for parts and labor, depending on whether the switch or wiring needs replacement.