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 the cruise control cable adjustment, should have minimum slack. |
| • | Inspect for the stored Diagnostic Trouble Codes (DTCs) in the PCM. Refer to Powertrain OBD System check in Engine Controls. |
| • | 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 Switch. |
| • | When an over/undercharged battery condition does not exist. |
| • | With normal engine RPM. |
| • | Without high engine RPM (fuel cut-off). Refer to Powertrain Control Module Description in Engine Controls for additional information. |
Test Description
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
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 16 |
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 17 |
4 |
Does the test lamp illuminate ? | -- | Go to Step 21 | Go to Step 5 |
5 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 14 |
6 | Probe the brake input 1 (cruise release) switch circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 23 |
7 | Depress the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 19 | Go to Step 8 |
8 | Probe the Brake 2 (stoplamp) switch circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 20 | Go to Step 9 |
9 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 22 |
10 | Probe the cruise disable circuit with a test lamp that is connected to B+. Does the test lamp illuminate? | -- | Go to Step 31 | Go to Step 11 |
11 | Use a scan tool in order to command the cruise inhibit OFF. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 25 |
12 | Probe the cruise engaged output circuit with a DMM that is connected to a good ground. Does the voltage measure near the specified value? | B+ | Go to Step 13 | Go to Step 26 |
13 | Check the speedometer for proper operation. Does the speedometer operate properly? | -- | Go to Step 24 | Go to Speedometer and/or Odometer Inoperative in Instrument Panel, Gauges and Console |
14 | Using a test lamp connected to a good ground, probe the cruise control switch ignition positive voltage feed at connector C2, terminal A. Does the test lamp illuminate? | -- | Go to Step 15 | Go to Step 28 |
15 | Using a test lamp connected to a good ground, probe the cruise control switch at connector C2 terminal D Does the test lamp illuminate? | -- | Go to Step 28 | Go to Step 36 |
16 | Repair the open circuit,high resistance or short to ground on the cruise control module ignition positive voltage circuit. Did you find and correct the condition? | -- | Go to Step 46 | -- |
17 | Repair the open circuit or high resistance in the cruise control module ground circuit. Did you find and correct the condition? | -- | Go to Step 46 | -- |
18 | Repair the short to voltage on the cruise control disable circuit. Did you find and correct the condition? | -- | Go to Step 46 | -- |
19 | Repair the short to voltage on the brake input 1 circuit. Did you find and correct the condition? | -- | Go to Step 46 | -- |
20 | Repair the short to voltage on the brake input 2 circuit. Did you find and correct the condition? | -- | Go to Step 46 | -- |
21 | Test the circuit that illuminated the test lamp for a short to voltage. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 36 |
22 | Test the brake input 2 circuit for an open or a high resistance. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 29 |
23 | Test the brake input 1 (cruise release) circuit for an open or a high resistance. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 30 |
24 | 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 46 | Go to Step 39 |
25 | Test the cruise inhibit circuit for an open, a high resistance, or a short to voltage. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 39 |
26 | Test the cruise engaged output circuit for an open, a high resistance, or a short to ground. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 39 |
27 | Test the cruise control switch ignition positive voltage circuit for an open a high resistance or short to ground. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 37 |
28 | Test the on/off circuit for an open or a high resistance. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 36 |
29 | Test the stop lamp ignition positive voltage feed for an open, high resistance or short to ground. Did you find and correct the condition | -- | Go to Step 46 | Go to Step 32 |
30 | Test the brake 1 (cancel) switch ignition positive voltage circuit for an open, high resistance or short to ground. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 32 |
31 | Test the cruise inhibit circuit for a short to ground. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 39 |
32 | Inspect the stoplamp switch for proper adjustment. Refer to Stop Lamp Switch Adjustment . Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 41 |
33 | Inspect the brake (cruise release) switch for proper adjustment. Refer to Brake Release Switch Replacement . Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 34 |
34 | Inspect for poor connections at the harness connector of the brake (cruise release) switch. Refer to Intermittents and Poor Connections Diagnosis and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 40 |
35 | Inspect for poor connections at the harness connector of the stoplamp switch. Refer to Intermittents and Poor Connections Diagnosis and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 41 |
36 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Intermittents and Poor Connections Diagnosis and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 42 |
37 | Inspect for poor connections at the harness connector of the right IP junction block. Refer to Intermittents and Poor Connections Diagnosis and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 43 |
38 | Inspect for poor connections at the harness connector of the cruise control module. Refer to Intermittents and Poor Connections Diagnosis and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 44 |
39 | Inspect for poor connections at the harness connector of the PCM. Refer to Intermittents and Poor Connections Diagnosis and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 46 | Go to Step 45 |
40 | Replace the brake (cruise release) switch. Refer to Cruise Control Switch Replacement . Did you complete the replacement? | -- | Go to Step 46 | -- |
41 | Replace the stoplamp switch. Refer to Stop Lamp Switch Replacement in Brakes. Did you complete the replacement? | -- | Go to Step 46 | -- |
42 | Replace the cruise control switch. Refer to Cruise Control Switch Replacement . Did you complete the replacement? | -- | Go to Step 46 | -- |
43 | Replace the right IP junction block. Refer to Relay/Fuse Center Replacement . Did you complete the replacement? | -- | Go to Step 46 | -- |
44 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 46 | -- |
45 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Did you complete the replacement? | -- | Go to Step 46 | -- |
46 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 |
