B1001 — HVAC Control Module Voltage High
What it means: HVAC Control Module Voltage High.
How serious / can you keep driving: Caution. Limp to the next safe stop.
Check first: Check charging system voltage
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Indianapolis, IN
Closest first. Tell them B1001 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Indianapolis, IN · (317) 789-5002
- 0.0 mi away — based in Indianapolis, IN · (317) 300-7000
- 0.0 mi away — based in Indianapolis, IN · (317) 646-8208
Seen on: Heavy Truck
What B1001 means
HVAC Control Module Voltage High. Common causes: HVAC control module over-voltage.
How serious is it?
Caution. Limp to the next safe stop.
Most likely causes
- HVAC control module over-voltage
- Charging system overvoltage
- alternator fault
First moves (roadside)
- Check charging system voltage
- should be 13.8-14.5V
- check for spikes
FAQ
HVAC Control Module Voltage High. Common causes: HVAC control module over-voltage.
Caution — Limp to the next safe stop.
The most common cause is: HVAC control module over-voltage. Other possibilities include Charging system overvoltage; alternator fault.
Limp to the next safe stop. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside B1001, or share the same subsystem.
- Blower Motor Circuit Open (B1004)
- Blower Motor Circuit Short to Ground (B1005)
- APU HVAC Communication Fault (B1050)
- Coolant/Diesel Heater Circuit Fault (B1052)
- HVAC Control Module Voltage Low (B1002)
- A/C Pressure Sensor Circuit Fault (B1010)
- Air Distribution Actuator Fault (B1040)
- Temperature Blend Door Actuator Fault (B1041)
Same symptom: Charging and voltage
Other codes that trace back to voltage — one bad ground can set half a dozen of them at once.
- Oil pressure sensor — voltage high (SPN 100 FMI 3) · Lubrication
- Oil pressure sensor — voltage low (SPN 100 FMI 4) · Lubrication
- Boost sensor — voltage low (SPN 102 FMI 4) · Engine
- Intake manifold temp — voltage high (SPN 105 FMI 3) · Engine
- Intake manifold temp — voltage low (SPN 105 FMI 4) · Engine
- Coolant temp sensor — voltage high (SPN 110 FMI 3) · Cooling
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.