Circuit Description
The malfunction indicator lamp (MIL) request circuit signals the engine control module (ECM) that the transmission control module (TCM) is requesting MIL illumination.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The TCM is requesting MIL illumination or the MIL request circuit is shorted to ground.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Connect a scan tool. Are there any transmission DTCs set? | -- | Go to Step 3 | Go to Step 5 | |
3 | Diagnose and repair any transmission DTCs. Refer to Diagnostic Trouble Code (DTC) List/Type in Automatic Transmission. Did you complete the action? | -- | Go to Step 4 | -- |
4 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions |
5 |
Does the voltage measure near the specified value? | B + | Go to Step 7 | Go to Step 6 |
6 | Test the MIL request circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
7 | Replace the TCM. Refer to Transmission Control Module Replacement in Automatic Transmission-Allison. Did you complete the replacement? | -- | Go to Step 9 | -- |
8 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Does the DTC run and pass? | -- | Go to Step 10 | Go to Step 2 |
10 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
