Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
BCM Code B337, Loss Of A/C-Heater Programmer Data: Notes
Code B337 will set if ignition is on and BCM has lost data communication with A/C-heater programmer. Fault can be caused by a loss of 12-volt power, ground to programmer or a double open in programmer data line, one on each side of component. During a failure, A/C clutch is disabled and blower motor runs at a constant 6 volts.
- Ensure code is not intermittent.
- Determines if fault is due to power or ground circuits or data line.
- Determines if data line fault is due to wiring or programmer.
- Checks IGN 3 to programmer.
- Determines if loss of ground is due to programmer, wiring or CPS.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.