Diagnostic Aids
To avoid misdiagnosis:
| • | Inspect for proper operation of the brake lamps. |
| • | Inspect throttle linkage for mechanical binding which could cause the system to malfunction. |
| • | Inspect cruise control cable for adjustment. It should have minimum slack. |
| • | EMI on the speed sensor signal circuit may cause erratic cruise control operation. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Cruise Control Schematics | ||||
1 | Did you perform the Cruise Control Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the test lamp illuminate? | -- | Go to Step 3 | Go to Step 29 |
3 | Connect the test lamp between the ignition voltage circuit and the ground circuit of the cruise control module. Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 30 |
4 |
Does the test lamp illuminate on any of the circuits? | -- | Go to Step 14 | Go to Step 5 |
5 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 15 |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 17 |
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 18 |
8 | Connect a test lamp between the cruise release signal circuit and a good ground. Does the test lamp illuminate? | -- | Go to Step 13 | Go to Step 19 |
9 | Connect a test lamp between the stop lamp signal circuit and a good ground. Does the test lamp illuminate? | -- | Go to Step 20 | 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 21 |
11 | Measure the voltage at the cruise control engaged signal circuit. Does the voltage measure near the specified value? | B+ | Go to Step 12 | Go to Step 22 |
12 | Check the speedometer for proper operation. Does the speedometer operate properly? | -- | Go to Step 23 | Go to Speedometer and/or Odometer Inaccurate or Inoperative in Instrument Panel, Gages and Console |
13 |
Does the test lamp illuminate? | Go to Step 31 | Go to Step 9 | |
14 | Test the suspected switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 27 |
15 | Test the cruise on/off signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 16 |
16 | Test the ignition voltage circuit of the cruise control On/Off switch for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 27 |
17 | Test the cruise control set/coast switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 27 |
18 | Test the cruise resume/accelerate signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 27 |
19 | Test the cruise control release switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 24 |
20 | Test the stop lamp 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 36 | Go to Stop Lamps Always On in Lighting Systems |
21 | Test the stop lamp signal circuit for an open or a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Stop Lamps Inoperative in Lighting Systems |
22 | Test the cruise engaged signal circuit for an open, for a high resistance, or for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 26 |
23 | Test the vehicle speed signal circuit for an open or for a high resistance between the PCM and cruise control module. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 28 |
24 | Inspect the cruise control release switch for proper adjustment. Refer to Cruise Release Switch Adjustment in Cruise Control. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 25 |
25 | Inspect for poor connections at the harness connector of the cruise control release switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 32 |
26 | 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 36 | Go to Step 33 |
27 | Inspect for poor connections at the harness connector of the multifunction turn signal lever . Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 34 |
28 | Inspect for poor connections at the harness connector of the cruise control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 36 | Go to Step 35 |
29 | Repair the ignition voltage circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 36 | -- |
30 | Repair the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 36 | -- |
31 | Repair a short to voltage in the cruise control release circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 36 | -- | |
32 | Replace the cruise control release switch. Refer to Cruise Control Release Switch Replacement in Cruise Control. Did you complete the replacement and adjustment? | -- | Go to Step 36 | -- |
33 |
Important: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 3.1L or to Powertrain Control Module Replacement in Engine Controls - 3.8L. Did you complete the replacement? | -- | Go to Step 36 | -- |
34 | Replace the cruise control switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 36 | -- |
35 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 36 | -- |
36 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 |
