What Does P2634 Mean?
The fuel pump 'B' control circuit voltage is above the expected threshold. The ECM has detected excessive voltage in the secondary or auxiliary fuel pump control circuit, suggesting an open circuit, short to power, or driver circuit malfunction.
Common Causes
35%
Open circuit in fuel pump control wiring or poor connection at connector
30%
Failed fuel pump driver module or ECM with stuck-high output
20%
Short to voltage in the fuel pump control circuit wiring
15%
Failed fuel pump 'B' with open internal circuit
Diagnostic Steps
1
Step 1: Inspect fuel pump 'B' control circuit wiring and connectors for damage, corrosion, or loose connections
2
Step 2: Disconnect fuel pump 'B' and measure voltage on the control wire from ECM/driver module with key on
3
Step 3: Check for continuity in the control circuit from ECM/driver module to fuel pump connector
4
Step 4: Test fuel pump driver module operation by commanding pump on/off with scan tool while monitoring voltage
5
Step 5: If circuit tests normal, verify fuel pump 'B' electrical integrity and resistance
Estimated Repair Cost
$150 - $850
Parts + labor, varies by vehicle and location
The fuel pump 'B' control circuit voltage is above the expected threshold. The ECM has detected excessive voltage in the secondary or auxiliary fuel pump control circuit, suggesting an open circuit, short to power, or driver circuit malfunction.
The most common cause of P2634 (Fuel Pump "B" Control Circuit High) is: Open circuit in fuel pump control wiring or poor connection at connector
Typical repair costs for P2634 range from $150 to $850, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may run on primary fuel pump only, causing performance issues under load or acceleration. Should be repaired soon to ensure adequate fuel delivery.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2634 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
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