Diagnostic Aids
Important: Perform the following in order to avoid misdiagnosis:
| • | Inspect for proper operation of brake lamps. |
| • | Inspect the throttle linkage for mechanical binding which could cause the system to malfunction. |
| • | Inspect for stored DTCs in the powertrain control module (PCM). Refer to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information. |
| • | 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 by the park/neutral position (PNP) switch |
| • | When an over/undercharged battery condition does not exist |
| • | With normal engine RPM |
| • | Without high engine RPM e.g. 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 36 |
3 | Probe the ignition positive voltage circuit of the cruise control module 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 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 release switch 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 go out? | -- | Go to Step 10 | Go to Step 22 |
10 | Probe the stop lamp switch 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 inhibit 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 OFF. Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 26 |
14 | Probe the cruise 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 Symptoms - Instrument Panel, Gages and Console in Instrument Panel, Gages, and Console |
16 | 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 43 | Go to Step 34 |
17 | Test the ON/OFF 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 43 | Go to Step 18 |
18 | Test the ignition positive voltage circuit for an open or high resistance between the cruise control module and the cruise control switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
19 | Test the set/coast 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 43 | Go to Step 34 |
20 | Test the resume/accelerate 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 43 | Go to Step 34 |
21 | Test the cruise release switch 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 43 | Go to Step 29 |
22 | Test the cruise release switch 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 43 | Go to Step 29 |
23 | 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 43 | Go to Step 30 |
24 | 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 43 | Go to Step 30 |
25 | Test the cruise inhibit 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 43 | Go to Step 33 |
26 | Test the cruise inhibit 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 43 | Go to Step 33 |
27 | Test the cruise engaged output 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 43 | Go to Step 33 |
28 | Test the speed sensor circuit for an open or a high resistance between the powertrain control module (PCM) and the cruise control module. Refer to Circuit Testing 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 release switch for proper adjustment. Refer to Cruise Release Switch Adjustment . Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 31 |
30 | 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 43 | Go to Step 32 |
31 | Inspect for poor connections at the harness connector of cruise release 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 43 | Go to Step 38 |
32 | 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 43 | Go to Step 39 |
33 | 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 43 | Go to Step 40 |
34 | 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 43 | Go to Step 41 |
35 | 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 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 release switch. Refer to Cruise Control 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 Lighting Systems. Did you complete the replacement? | -- | Go to Step 43 | -- |
40 | 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 43 | -- |
41 | Replace the multifunction turn signal lever . Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 43 | -- |
42 | 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 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 |
