Code B337, Loss Of HVAC Programmer Data (TORONADO)

Code B337 will set if the ignition is on and the BCM is not able to exchange data with the programmer. This can occur if the HVAC loses ignition, ground, or both serial data circuits.

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

Fig 1: Code B337, Loss of HVAC Programmer Data (Toronado)

Fig 2: Code B337, Schematic