Circuit Description
The ignition control module (ICM) creates a 4X signal and a 24X signal that is used by the powertrain control module (PCM) for ignition and fuel control. If the PCM does not receive 4X reference pulses from the ICM for more than 0.4 second while the engine is running, DTC P1320 is set.
Conditions for Running the DTC
The engine speed is more than 568 RPM.
Conditions for Setting the DTC
No 4X reference pulse has been received by the PCM for 0.4 second.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Diagnostic Aids
This DTC may set due to a false start condition in which cranking the engine exceeds 568 RPM but does not start.
If no fault is present, inspect for intermittent opens or shorts or electromagnetic interference (EMI).
Without 4X reference pulses the vehicle will start although crank time can be extended to as much as 45 seconds. If this DTC is set with a No Start complaint crank the vehicle for 45 seconds before attempting to determine the cause of a No Start condition.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Using Freeze Frame and Failure Records may help locate an intermittent condition. Operate the vehicle within the same conditions that you observed in the Freeze Frame and Failure Records.
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This step is testing the ICM 4X signal circuit for a short to voltage.
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This step is testing the continuity of the 4X signal circuit. If the DMM displays OL, an open circuit, or poor PCM connection is indicated.
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This step is testing the 4X signal circuit and the PCM. If the resistance value displayed on the DMM changes as the ignition is turned OFF, then the 4X signal circuit and the PCM are OK.
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This step is testing the ground circuit for the ICM. An open ground circuit can cause a variety of ignition control concerns.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Diagnostic Aids | ||
Is the voltage the less than the value specified? | 0.5 V | |||
Measure the continuity of the 4X signal circuit with the DMM connected to battery ground. Refer to Testing for Continuity in Wiring Systems. Does the DMM display OL? | -- | |||
Does the resistance value change when the ignition is turned OFF. | -- | |||
Does the DMM display continuity? | -- | |||
7 |
Did you find and correct the condition? | -- | ||
8 |
Did you find and correct the condition? | -- | ||
9 |
Did you find and correct the condition? | -- | ||
10 | Repair the ICM ground circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
11 | Repair the ICM 4X circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
12 | Replace the ICM. Refer to Ignition Control Module Replacement . Is the action complete? | -- | -- | |
13 |
Important: The replacement PCM must programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
14 |
Does the scan tool indicate that this test ran and passed? | -- | ||
15 | Select the Capture Info option and the Review Info option with the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
