Diagnostic Aids
Important: Perform the following in order to avoid misdiagnosis.
| • | Inspect for proper operation of brake lamps. |
| • | Inspect throttle linkage for mechanical binding which could cause the system to malfunction. |
| • | Inspect cruise control cable adjustment, should have minimum slack. |
| • | Inspect for stored Diagnostic Trouble Codes (DTCs) in the PCM. |
| • | EMI on the speed sensor signal circuit may cause erratic cruise control operation. |
Conditions for Enabling Cruise Control
| • | When vehicle speed is more than 40 km/h (25 mph) |
| • | When PARK, REVERSE, NEUTRAL, or 1st gear is not indicated. |
| • | When an over/undercharged battery condition does not exist. |
| • | With normal engine RPM. |
| • | Without high engine RPM (fuel cut-off). |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Cruise Control Schematics | ||||
1 | Did you perform the Cruise Control System Check? | -- | Go to Step 2 | |
2 |
Does the test lamp illuminate? | -- | Go to Step 3 | Go to Step 36 |
3 | Probe the ignition positive voltage circuit of the cruise control module harness connector with a test lamp that is connected to the ground circuit of the cruise control module. Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 37 |
4 |
Does the test lamp illuminate on any of the signal circuits? | -- | Go to Step 16 | Go to Step 5 |
5 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 17 |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 19 |
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 20 |
8 | Probe the cruise control brake 1 signal circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 21 |
9 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 22 | Go to Step 10 |
10 | Probe the brake 2 signal circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 23 | Go to Step 11 |
11 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 24 |
12 | Probe the cruise control disable signal circuit with a test lamp that is connected to B+. Does the test lamp illuminate? | -- | Go to Step 25 | Go to Step 13 |
13 | Use a scan tool in order to command the cruise inhibit/enable OFF. Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 26 |
14 | Probe the cruise control engaged signal circuit with a DMM that is connected to a good ground. Does the voltage measure near the specified value? | B+ | Go to Step 15 | Go to Step 27 |
15 | Check the speedometer for proper operation. Does the speedometer operate properly? | -- | Go to Step 28 | Go to Speedometer and/or Odometer Inoperative in Instrument Panel, Gauges and Console |
16 | Test the signal circuit that illuminated the test lamp for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
17 | Test the cruise control on switch signal circuit for an open or a high resistance and the set/coast, resume/accel signal circuits for a short to ground. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 18 |
18 | Test the ignition positive voltage circuit for an open or high resistance between the instrument panel junction block and the cruise control switch. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
19 | Test the cruise control set/coast signal circuit for an open or a high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
20 | Test the cruise control resume/accelerate signal circuit for an open or a high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
21 | Test the cruise control brake 1 switch signal circuit for an open or a high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 29 |
22 | Test the cruise control brake 1 switch signal circuit for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 29 |
23 | Test the brake 2, stop lamp switch signal circuit for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 30 |
24 | Test the brake 2, stoplamp switch signal circuit for an open or a high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 30 |
25 | Test the cruise inhibit signal circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 33 |
26 | Test the cruise disable signal circuit for an open, a high resistance, or a short to voltage. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 33 |
27 | Test the cruise engaged signal circuit for an open, a high resistance, or a short to voltage. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 33 |
28 | Test the speed sensor circuit for an open or a high resistance between the PCM and cruise control module. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 35 |
29 | Inspect the cruise control brake switch for proper adjustment. Refer to Brake Release Switch Adjustment . Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 31 |
30 | Inspect the stoplamp switch for proper adjustment. Refer to Stop Lamp Switch Adjustment . Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 32 |
31 | Inspect for poor connections at the harness connector of the cruise control brake switch. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 38 |
32 | Inspect for poor connections at the harness connector of the stoplamp switch. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 39 |
33 | Inspect for poor connections at the harness connector of the PCM. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 40 |
34 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 41 |
35 | Inspect for poor connections at the harness connector of the cruise control module. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 42 |
36 | Repair the ignition positive voltage circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 43 | -- |
37 | Repair the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 43 | -- |
38 | Replace the cruise control brake switch. Refer to Brake Release Switch Replacement . Did you complete the replacement? | -- | Go to Step 43 | -- |
39 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Did you complete the replacement? | -- | Go to Step 43 | -- |
40 |
Important: The PCM must be programed before replacement. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Replace the PCM. Refer to Powertrain Control Module Replacement 2.4L or Powertrain Control Module Replacement/Programming 3.1L in Engine Controls. Did you complete the replacement? | -- | Go to Step 43 | -- |
41 | Replace the multifunction turn signal lever. Refer to Cruise Control Switch Replacement in Steering Wheel and Column - Tilt. Did you complete the replacement? | -- | Go to Step 43 | -- |
42 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 43 | -- |
43 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 |
