P0737 - TCM Engine Speed Output Circuit Malfunction
The Transmission Control Module (TCM) monitors engine speed via a dedicated circuit to manage shift timing and torque converter lockup. Code P0737 indicates a fault in this circuit, often due to wiring issues, a faulty TCM, or a problem with the engine speed sensor signal. This can cause erratic shifting, poor performance, and potential transmission damage if ignored.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Harsh or delayed shifting
- Transmission stuck in limp mode
- Poor acceleration or fuel economy
2. Most Common Causes
- Damaged or corroded wiring/connectors in the TCM engine speed circuit
- Faulty engine speed (crankshaft position) sensor
- Malfunctioning Transmission Control Module (TCM)
- Short or open circuit in the signal wire
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect wiring and connectors for damage, corrosion, or loose connections.
Step 3: Test engine speed sensor signal using a multimeter or oscilloscope.
Step 4: Check TCM for proper power, ground, and communication; perform TCM reset if needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with P0737 can cause erratic shifting and potential transmission damage. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs typically range from $50 to $150 for wiring repairs or sensor replacement, but TCM replacement can be more expensive.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.