Circuit Description
The wait to start indicator illuminates in the message center when the engine control module (ECM) commands the glow plugs ON. The ECM provides the ground for the wait to start indicator control circuit. The ECM monitors the voltage on the control circuit in order to determine if there is a circuit malfunction. The ECM should detect a low voltage when the indicator is illuminated and a high voltage when the indicator is not illuminated.
Conditions for Running the DTC
| • | The ignition is in ON. |
| • | The ignition voltage is between 9-16 volts. |
Conditions for Setting the DTC
| • | The ECM detects a lower than normal voltage at the control circuit of the wait to start indicator when the ECM commands the indicator to illuminate. |
| • | The ECM detects a higher than normal voltage at the control circuit of the wait to start indicator when the ECM is not commanding the indicator to illuminate. |
Diagnostic Aids
| • | The DTC may be intermittent. For intermittent diagnosis, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | If any additional DTCs are stored, refer to Diagnostic Trouble Code (DTC) List in Engine Controls - 7.8L. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The wait to start indicator illuminates briefly when the ignition is turned ON. The ON time depends upon the temperature of the engine at the time.
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If the fuse opens during this test, there is a short to voltage on the control circuit.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Instrument Cluster Schematics | |||
1 | Did you perform the Instrument Cluster Diagnostic System Check? | Go to Step 2 | |
Does the wait to start indicator illuminate and then turn OFF? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
3 | Does the wait to start indicator illuminate continuously in the message center? | Go to Step 6 | Go to Step 4 |
4 | Does the wait to start indicator not illuminate in the message center with the ignition ON? | Go to Step 5 | Go to Diagnostic Aids |
Does the wait to start indicator illuminate in the message center? | Go to Step 10 | Go to Step 7 | |
6 |
Does the wait to start indicator illuminate in the message center? | Go to Step 8 | Go to Step 10 |
7 | Test the wait to start indicator control circuit for an open, for a short to voltage or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
8 | Test the wait to start indicator control circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
9 | Inspect for poor connections at the harness connector of the message center. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
10 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
11 | Replace the message center. Refer to Telltale Circuit Board Replacement . Did you complete the replacement? | Go to Step 13 | -- |
12 |
Important: Program the replacement ECM. Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data in Engine Controls - 7.8L. Did you complete the replacement? | Go to Step 13 | -- |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
