Analog Cluster

Code B336 will set if the ignition is on and the BCM loses data communication with the Instrument Panel Cluster (IPC). The problem is a result of a +7 volt power or ground fault to the IPC, or a double open circuit in the data communication line between the IPC and the BCM. If this occurs, the cruise control will disengage (if on) and the headlamps (if on) will be on low beams.
1. This step checks for an intermittent condition.
2. This step checks if the problem is related to the power and ground circuits or the data communication line.
3. This step determines if the data problem is due to the IPC or wiring.
4. This step determines if the fault is due to opens in CKTs 800A and 800B or an internal IPC problem.
5. This step checks if the fault is due to the +7 volt power circuit or the ground circuit from the Central Power Supply (CPS).
6. This step checks the ground circuit for an open, a faulty IPC, or a faulty CPS.

Note on Intermittents
If a B336 code shows as "History", without any other data codes, then check the +7 volt power, ground and data line for intermittent faults. If other data codes are stores, see "Multiple Intermittent Codes."