Gas Cap Indicator

The gas cap indicator indicates when a gross leak detected in the on-board fuel vapor recovery system. This indicator is controlled by the Instrument Panel Cluster (IPC) logic circuit, based upon the IPC programming and electronic messages received over the CAN Bus from the PCM.

The PCM continually monitors the on-board vapor recovery system to determine whether there are air leaks in the system. The PCM then sends the proper lamp-ON or lamp-OFF message to the IPC. If the IPC turns ON the gas cap indicator due to a monitored gross leak in the vapor recovery system, it may indicate that the gas cap has been removed or is improperly installed.

The gas cap indicator function is controlled by the IPC logic circuit, and only allows the indicator to operate when the IPC receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the gas cap indicator will always be OFF when the ignition switch is in any position except ON or START. The IPC will turn ON the gas cap indicator for the following reason:

• Gas Cap Indicator Lamp-On Message  - Each time the IPC receives an electronic gas cap indicator lamp-ON  message from the PCM indicating there is a gross leak in the vapor recovery system, the gas cap indicator will be illuminated. The indicator remains illuminated until the IPC receives a lamp-OFF message from the PCM, or until the ignition switch is turned to the OFF position.