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B1002 — HVAC Control Module Voltage Low

CautionHVACLimp to the next safe stop

Seen on: Heavy Truck

HVAC Control Module Voltage Low. Common causes: HVAC control module under-voltage.

Don't risk it — get a diesel tech on the truck.

Your code rides along, so nearby mechanics see the fault before they quote you.

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How serious is it?

Caution. Limp to the next safe stop.

Most likely causes

  1. HVAC control module under-voltage
  2. Battery or alternator fault
  3. high resistance connection

First moves (roadside)

  1. Check battery voltage
  2. test alternator output
  3. inspect power connections

FAQ

What does B1002 mean?

HVAC Control Module Voltage Low. Common causes: HVAC control module under-voltage.

How serious is B1002?

Caution — Limp to the next safe stop.

What's the most likely cause of B1002?

The most common cause is: HVAC control module under-voltage. Other possibilities include Battery or alternator fault; high resistance connection.

Can I keep driving with B1002?

Limp to the next safe stop. When in doubt, get a qualified mobile diesel tech on the truck before continuing.

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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.