Diagnostic Aids
To avoid misdiagnosis:
| • | Inspect for proper operation of the brake lamps. |
| • | Inspect for stored Diagnostic Trouble Codes (DTC's in the ECM). Refer to Diagnostic System Check - Engine Controls 3.0L (L81) in Engine Controls. |
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. |
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform A Diagnostic System Check - Cruise Control? | Go to Step 2 | |
2 |
Does the test lamp illuminate? | Go to Step 11 | Go to Step 3 |
3 | Probe the ON signal circuit of the ECM harness connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 5 | Go to Step 4 |
4 |
Does the test lamp illuminate? | Go to Step 12 | Go to Step 13 |
5 |
Does the test lamp illuminate? | Go to Step 6 | Go to Step 14 |
6 |
Does the test lamp illuminate? | Go to Step 7 | Go to Step 15 |
7 | Probe the stop lamp signal circuit of the ECM harness connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 21 | Go to Step 8 |
8 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | Go to Step 9 | Go to Step 16 |
9 | Probe the cruise release signal circuit of the ECM harness connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 10 | Go to Step 17 |
10 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | Go to Step 19 | Go to Step 25 |
11 | 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 30 | Go to Step 23 |
12 | Test the ON signal circuit for a open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 24 |
13 | Test the ignition positive voltage circuit of the cruise control switch for an open or high resistance or a short to ground and the cruise control 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 30 | Go to Step 24 |
14 | Test the SET/ACCEL circuit for a open or high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 24 |
15 | Test the RESUME/DECEL signal circuit for a open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 24 |
16 | Test the ignition positive voltage circuit of the stop lamp switch for a open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 20 |
17 | Test the cruise release signal circuit for a open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 18 |
18 | Test the ignition positive voltage circuit of the cruise release switch for a open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 22 |
19 | Test the cruise release 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 30 | Go to Step 22 |
20 | Test the stop lamp signal circuit for a open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 23 |
21 | 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 30 | Go to Step 23 |
22 | Inspect for poor connections at the harness connector of the cruise control 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 30 | Go to Step 26 |
23 | 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 30 | Go to Step 27 |
24 | Inspect for poor connections at the multifunction turn signal lever harness connector for 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 30 | Go to Step 28 |
25 | Inspect for poor connections at the harness connector of the ECM. 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 30 | Go to Step 29 |
26 | Replace the cruise control release switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Did you complete the replacement and adjustment? | Go to Step 30 | -- |
27 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Did you complete the replacement? | Go to Step 30 | -- |
28 | Replace the multifunction turn signal lever. Refer to Turn Signal Switch Replacement - On Vehicle in Steering Wheel - Column and Tilt . Did you complete the replacement? | Go to Step 30 | -- |
29 | Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls. Did you complete the replacement? | Go to Step 30 | -- |
30 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | System OK | Go to Diagnostic Aids |
