Code B337, Loss Of HVAC Programmer Data

Code B337 will set if communication between programmer and BCM is lost. This can occur if HVAC loses ignition circuit, ground circuit or both serial data circuits.

1. Checks for power and ground up to programmer. Test light should be on when connected from ignition source to both grounds.
2. Since power and ground are available to programmer, source for failure is either a double open in circuit No. 800 or faulty terminal contacts.

Fig 1: Code B337, Schematic, Loss of HVAC Programmer Data

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code B337, Flow Chart, Loss of HVAC Programmer Data

Courtesy of GENERAL MOTORS CORP.