What Does P0B35 Mean?
The hybrid powertrain control module has detected a low voltage condition on the high-voltage service disconnect monitoring circuit. The signal voltage is below the expected threshold, which may indicate a short to ground in the wiring, a faulty interlock switch stuck in the open position, or a corroded connector reducing the signal level.
Safety Warning
Do not drive. A low-signal fault on the disconnect circuit means the vehicle may not correctly detect the disconnect state, creating an electrocution hazard during service.
Common Causes
35%
Short to ground in the service disconnect monitoring circuit wiring
30%
Service disconnect interlock switch stuck closed or internally shorted
20%
Corroded connector pins at the hybrid control module causing voltage drop on the signal circuit
15%
Service disconnect plug contacts corroded, causing high resistance and low signal voltage
Diagnostic Steps
1
Step 1: Measure the service disconnect circuit voltage at the hybrid control module connector. Compare to manufacturer's expected low and high state voltages.
2
Step 2: Disconnect the wiring harness at the interlock switch and measure the signal wire for shorts to ground. Resistance to ground should be infinite (open circuit) with the switch disconnected.
3
Step 3: Check the interlock switch continuity in both positions (plug in and plug out). Verify it toggles between open and closed per specification.
4
Step 4: Inspect all connectors in the circuit for corrosion, water intrusion, or pushed-back pins that could cause a low voltage condition.
5
Step 5: If wiring and switch are good, check the hybrid control module's pull-up resistor and reference voltage on this circuit input.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The hybrid powertrain control module has detected a low voltage condition on the high-voltage service disconnect monitoring circuit. The signal voltage is below the expected threshold, which may indicate a short to ground in the wiring, a faulty interlock switch stuck in the open position, or a corr...
The most common cause of P0B35 (High Voltage Service Disconnect Circuit Low) is: Short to ground in the service disconnect monitoring circuit wiring
Typical repair costs for P0B35 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Do not drive. A low-signal fault on the disconnect circuit means the vehicle may not correctly detect the disconnect state, creating an electrocution hazard during service.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0B35 to identify the root cause.
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Quick Info
Category
Powertrain
System
High Voltage Safety System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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