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. |
| • | When testing vehicles equipped with steering wheel controls, the steering wheel must be rotated to each stop position while testing the cruise control switch signal circuits. This will ensure the integrity of the SIR coil. |
| • | Inspect for stored Diagnostic Trouble Codes (DTCs) in the PCM. |
| • | Electromagnetic interference (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 Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Does the test lamp illuminate? | -- | Go to Step 3 | Go to Step 35 |
3 | Connect the test lamp between the ignition 3 voltage circuit and the ground circuit of the cruise control module. Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 36 |
4 | Turn the cruise control On/Off switch OFF. Does the test lamp illuminate on any of the circuits? | -- | Go to Step 15 | Go to Step 5 |
5 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 16 |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 18 |
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 19 |
8 | Probe the TCC/Brake switch 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 20 |
9 | Probe the stop lamp switch signal circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 22 | Go to Step 10 |
10 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 23 |
11 | Probe the cruise control inhibit signal circuit with a test lamp that is connected to B+. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 25 |
12 | Use a scan tool in order to command the cruise inhibit/enable OFF. Does the test lamp illuminate? | -- | Go to Step 24 | Go to Step 13 |
13 | 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 14 | Go to Step 26 |
14 | Check the speedometer for proper operation. Does the speedometer operate properly? | -- | Go to Step 27 | Go to Speedometer and/or Odometer Inaccurate or Inoperative in Instrument Panel, Gages and Console |
15 | Test the circuit that illuminated the test lamp for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 33 |
16 | Test the cruise control on signal circuit for an open or a high resistance and the cruise control set/coast, resume/accel signal circuits for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 17 |
17 | Test the ignition positive voltage circuit of the cruise control switch for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 33 |
18 | Test the cruise control set/coast signal circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 33 |
19 | Test the cruise control resume/accelerate signal circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 33 |
20 | Test the TCC/Brake switch signal circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 28 |
21 | Test the TCC/Brake switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 28 |
22 | Test the stop lamp switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 29 |
23 | Test the stop lamp switch signal circuit for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 29 |
24 | Test the cruise control inhibit signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 32 |
25 | Test the cruise control inhibit signal circuit for an open, a high resistance, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 32 |
26 | Test the cruise control engaged signal circuit for an open, a high resistance, or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 32 |
27 | Test the speed sensor circuit for an open or a high resistance between the cruise control module and the powertrain control module (PCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 32 |
28 | Inspect the TCC/Brake switch for proper adjustment. Refer to Stop Lamp Switch Adjustment in Lighting Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 30 |
29 | Inspect the stop lamp switch for proper adjustment. Refer to Stop Lamp Switch Adjustment in Lighting Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 31 |
30 | Inspect for poor connections at the harness connector of the TCC/Brake switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 37 |
31 | Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 38 |
32 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 39 |
33 | 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 40 |
34 | Inspect for poor connections at the harness connector of the cruise control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 42 | Go to Step 41 |
35 | 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 42 | -- |
36 | Repair the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 42 | -- |
37 | Replace the TCC/Brake switch. Refer to Stop Lamp Switch Replacement in Lighting Systems. Did you complete the replacement? | -- | Go to Step 42 | -- |
38 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Lighting Systems. Did you complete the replacement? | -- | Go to Step 42 | -- |
39 |
Important: The PCM must be reprogrammed after replacement. Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 42 | -- |
40 | Replace the cruise control switch. Refer to Steering Wheel Control Switch Assembly Replacement in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 42 | -- |
41 | Replace the cruise control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 42 | -- |
42 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 |
