Wait-To-Start Indicator

The wait-to-start indicator gives an indication to the vehicle operator when the diesel engine is too cool for efficient and reliable engine starting, and the engine glow plugs are energized in their preheat operating mode. This indicator is controlled by the IC logic circuit board based upon programming and electronic messages received by the IC from the PCM over the CAN data bus.

The wait-to-start indicator function of the electronic display unit is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the indicator will always be OFF when the ignition switch status is anything except ON or START. The IC will turn ON the wait-to-start indicator for the following reasons:

• Wait-To-Start Indicator Lamp-On Message  - Each time the IC receives an electronic wait-to-start indicator lamp-ON  message from the PCM indicating that the air temperature is too cool for efficient and reliable engine starting and the glow plugs are energized in their preheat mode, the wait-to-start indicator will be illuminated. The indicator remains illuminated until the IC receives a lamp-OFF message from the PCM, until the PCM detects that the engine is running, or until the ignition switch status transitions to OFF, whichever occurs first.

The PCM continually monitors the glow plug control circuits to determine when they are energized in their preheat operating mode. The PCM then sends the proper lamp-ON or lamp-OFF message to the IC. For proper diagnosis of the wait-to-start indicator, the PCM, the IC, the CAN data bus or the electronic communication related to wait-to-start indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.