Important: Always perform the Diagnostic System Check - Instrument Cluster prior to using this diagnostic procedure.

Ignition voltage is supplied directly to the wait to start indicator. The engine control module (ECM) controls the lamp by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.

The ignition voltage is greater than 6 volts but less than 18 volts.

Important: Remove any debris from the ECM connector surfaces before servicing the ECM. Inspect the ECM connector gaskets when diagnosing/replacing the ECM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the ECM.

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.

The wait to start indicator illuminates only with the ignition ON and the engine OFF. The wait to start indicator will not illuminate during post-start glow plug operation.

The wait to start indicator will not stay ON for long at higher engine temperatures.

Schematic Reference

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

1. Ignition OFF, disconnect the harness connector at the ECM.
2. Ignition ON, verify that the wait to start indicator on the IPC is not illuminated.

⇒	If the indicator is illuminated, test the signal circuit for a short to ground. If the circuit tests normal, replace the IPC.

3. Install a 3-amp fused jumper between the signal circuit and ground. Verify that the wait to start indicator on the IPC illuminates.

⇒	If the indicator does not illuminate, test the signal circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the IPC.

4. If all circuits test normal, test or replace the ECM.