Diagnostic Aids
In order to avoid a misdiagnosis, inspect for proper operation of the brake lamps. Refer to Exterior Lighting Systems Description and Operation.
For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections.
Electromagnetic Interference on the vehicle speed sensor signal circuit may cause erratic cruise control operation.
Conditions for Enabling Cruise Control
| • | The CRUISE NOT READY message is not illuminated in the DIC. |
| • | The vehicle speed is greater than 40 km/h (25 mph). |
| • | The vehicle is not in PARK, REVERSE, NEUTRAL, or 1st gear. |
| • | The system voltage is within 9.2 volts and 16 volts. |
| • | The park brake is released. |
| • | The forward looking sensor (FLS) is radiating and the adaptive cruise module (ACM) has identified acceptable stationary or moving objects. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference : Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views or Engine Control Module Connector End Views for the 4.6L engine | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the Cruise Control Switch parameter display On? | -- | Go to Step 3 | Go to Step 5 |
3 |
Does the Cruise Control Switch parameter display Set? | -- | Go to Step 4 | Go to Step 9 |
4 |
Does the Cruise Control Switch parameter Display Resume? | -- | Go to Diagnostic Aids | Go to Step 9 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 11 | |
6 |
Does the voltage measure at or near the specified value? | B+ | Go to Step 7 | Go to Step 8 |
7 | Test the cruise control switch signal circuit for an open or for a short to ground between C7 and the BCM. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10 |
8 | Test the cruise control switch signal circuit for an open or for a short to ground between C7 and the cruise control switch. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 9 |
9 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 |
10 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 |
11 | Repair the open, the high resistance or the short to ground in the cruise control switch supply voltage circuit. Refer to Circuit Testing and Wiring Repairs. Did you complete the repair? | -- | Go to Step 14 | -- |
12 | Replace the cruise control switch. Refer to Turn Signal Multifunction Switch Replacement. Did you complete the replacement? | -- | Go to Step 14 | -- |
13 | Replace the BCM. Refer to Body Control Module Replacement in Computer/Integrating Systems. Did you complete the replacement? | -- | Go to Step 14 | -- |
14 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate properly? | -- | System OK | Go to Step 2 |
