Code B337, Loss Of HVAC Programmer Data

WARNING: This page is about a different car, the 1993 Buick Riviera and 1992 Buick Riviera. However, it is still accessible from the selected car via links, so may be relevant.

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

NOTE: Test numbers refer to numbers on diagnostic chart.

Checks for power and ground up to the programmer. The test light should be on when connected from ignition source to both grounds.
Since power and ground are 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, 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.