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 A 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 harness connector. 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 module harness connector Abs/TCC, release 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 stop lamp 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 inhibit 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 | |
16 | Test the signal circuit that illuminated the test lamp for a short to voltage. 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 and resume/accel signal circuits for a short to ground. 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 IP junction block and the cruise control switch. 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. 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. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
21 | Test the cruise control release switch signal circuit for an open or a high resistance. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 29 |
22 | Test the cruise control release switch signal circuit for a short to voltage. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 29 |
23 | Test the stoplamp switch signal circuit for a short to voltage. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 30 |
24 | Test the stoplamp switch signal circuit for an open or a high resistance. 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. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 33 |
26 | Test the cruise inhibit signal circuit for an open, a high resistance, or a short to voltage. 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. 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. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 35 |
29 | Inspect the cruise control 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 stoplamp switch for proper adjustment. Refer to Stop Lamp Switch Adjustment in Hydraulic Brakes. 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 release switch. 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. 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. 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. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 39 |
35 | Inspect for poor connections at the harness connector of the cruise control module. 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 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 Hydraulic Brakes. Did you complete the replacement? | -- | Go to Step 43 | -- |
40 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Did you complete the replacement? | -- | Go to Step 43 | -- |
41 | Replace the cruise control switch. Refer to Multifunction Lever Replacement . 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 |
