P1630: VCRM B+ Voltage Circuit Malfunction
The P1630 code indicates a fault in the B+ voltage supply circuit to the Variable Control Relay Module (VCRM). The VCRM controls the condenser fan speed using pulse-width modulation (PWM) based on signals from the PCM. This code sets when the PCM detects an abnormal B+ voltage to the VCRM, such as low voltage, an open circuit, or a short circuit, preventing proper fan operation.
01. Most Common Causes
- Blown or degraded VCRM circuit fuse
- Faulty fan control relay with corroded contacts
- Damaged, cut, or high-resistance wiring in the B+ circuit
- Corroded, bent, or loose pins in the VCRM connector
- Internally damaged VCRM module
- Weak battery or sulfated battery terminals
- Faulty alternator voltage regulator causing overvoltage or undervoltage
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Air conditioning condenser fan not operating or running erratically
- Reduced air conditioning performance
- Possible engine overheating in stop-and-go traffic
03. Step-by-Step Diagnosis
Check for technical service bulletins (TSBs) related to P1630 for the specific vehicle.
Inspect and test the VCRM fuse and relay; replace if faulty.
Visually inspect the VCRM connector and wiring for damage, corrosion, or loose connections.
Measure B+ voltage at the VCRM connector with the ignition on; should be battery voltage (12.6V or higher).
Test the VCRM by swapping with a known-good module if possible, or perform PWM output tests per manufacturer procedure.
Check battery condition and alternator output voltage (should be 13.5-14.5V at idle).
1. Frequently Asked Questions
Is it safe to drive?▼
You can drive short distances, but avoid heavy traffic or hot weather as the condenser fan may not work, reducing AC performance and potentially causing engine overheating. Have it diagnosed soon.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on the cause. A fuse or relay replacement is cheap ($20-$50), while a VCRM module can cost $150-$300 plus labor.