Circuit Description
The engine control module (ECM) replicates the signal received from the crankshaft position (CKP) sensor. This signal is sent to the fuel injection control module (FICM) through the engine speed signal circuit. The FICM uses this replicated signal to generate injection current and control the recharge of the fuel injection high voltage circuits. When cranking, the FICM has full control of the fuel injectors. The only input the FICM uses at this time is the engine speed signal from the ECM. The FICM monitors the signal along with the injection request signals from the ECM after the engine is running. If there is a problem with this signal, a diagnostic trouble code (DTC) could set.
Conditions for Running the DTC
The engine is cranking or running.
Conditions for Setting the DTC
The FICM does not receive a crank signal, but does receive injection requests from the ECM.
OR
The FICM receives an invalid crank signal from the ECM.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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. |
Diagnostic Aids
A missing high resolution signal will cause a no-start condition.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the scan tool display Last Test Failed? | -- | Go to Step 3 | Go to Intermittent Conditions |
3 |
Important: Use the proper terminal from J 35616 Connector Test Adapter Kit.
Does the voltage measure within the specified range? | 4.0-5.0 V | Go to Step 4 | Go to Step 5 |
4 | With the DMM still connected, measure the current from the engine speed signal circuit to a good ground. Does the current measure less than the specified value? | 10 mA | Go to Step 9 | Go to Step 6 |
5 | Does the voltage measure above the specified range? | 4.0-5.0 V | Go to Step 7 | Go to Step 8 |
6 | Repair the short to reference voltage on the engine speed signal circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 13 | -- |
7 | Test for a short to battery voltage, ignition voltage, or either 5-volt reference on the engine speed signal circuit. Repair as necessary. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
8 | Test the engine speed signal circuit for an open or a short to ground. Repair as necessary. refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
9 | Inspect for poor connections at the FICM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Repair as necessary. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
10 | Replace the fuel injection control module. Refer to Fuel Injector Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
11 | Inspect for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Repair as necessary. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
12 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 |
14 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
