Circuit Description
By pulse width modulating (PWM) the Cruise Control Servo Move Signal circuit the engine control module (ECM) indicates to the cruise control module how much accelerator pedal movement is necessary. The amount of pedal movement is determined by the duty cycle of the PWM signal, which is sent every 100 ms. DTC 1580 sets when Cruise Control Servo Move Signal circuit is commanded high, PWM is ON, and the voltage level at the ECM is low.
Conditions for Running the DTC
Continuously when the engine is running.
Conditions for Setting the DTC
| • | The ECM detects low feedback voltage when the Cruise Control Servo Move Signal circuit is commanded high. |
| • | The condition exists for 500 ms. |
Action Taken When the DTC Sets
| • | The ECM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
Important: To locate an intermittent problem, use the scan tool to monitor the C/C MOVE CKT. -LOW VOLT test with the ignition ON, and the engine OFF. The scan tool will display Test Fail when a short to ground exists in the Cruise Control Servo Move Signal circuit.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Connector End View Reference: Cruise Control Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Cruise Control? | Go to Step 2 | |
Does the Test Fail? | Go to Step 3 | Go to Diagnostic Aids | |
3 |
Does the Test Fail? | Go to Step 4 | Go to Step 5 |
4 | Inspect Cruise Control Servo Move Signal circuit for short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the problem? | Go to Step 7 | Go to Step 6 |
5 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the repair? | Go to Step 7 | -- |
6 |
Important: The replacement ECM must be programmed. Replace ECM. Refer to Engine Control Module Replacement in Engine Controls. Did you complete the repair? | Go to Step 7 | -- |
7 |
Does the DTC reset? | Go to Step 2 | System OK |
