Diagnostic Aids
Important: Perform the following in order to avoid misdiagnosis.
• Inspect for proper operation of brake lamps and clutch switch,
if equipped. • EMI on the speed sensor signal circuit may cause erratic cruise
control operation.
Conditions for Enabling Cruise Control
The vehicle speed is greater than 40 km/h (25 mph).
Test Description
The numbers below refer to step numbers on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Cruise Control Schematics | |||
1 | Did you perform A Diagnostic System Check - Cruise Control? | Go to Step 2 | |
2 |
Did the scan tool parameter change state? | Go to Step 3 | Go to Step 17 |
3 |
Did the cruise control Set/Coast parameter change state? | Go to Step 4 | Go to Step 20 |
4 |
Did the cruise control Resume Accelerate parameter change state? | Go to Step 5 | Go to Step 21 |
Did the stop lamp pedal switch parameter change state? | Go to Step 11 | Go to Step 6 | |
6 |
Does the test lamp illuminate? | Go to Step 7 | Go to Step 30 |
7 | Probe the stop lamp interface module harness connector ignition positive voltage circuit with a test lamp connected to the ground circuit of the stop lamp interface module. Does the test lamp illuminate? | Go to Step 8 | Go to Step 31 |
8 | Probe the stop lamp interface module harness connector stop lamp signal circuit, from the stop lamp switch, with a test lamp connected to a good ground. Does the test lamp illuminate? | Go to Step 22 | Go to Step 9 |
9 | Press the brake pedal. Does the test lamp illuminate? | Go to Step 24 | Go to Step 10 |
10 |
| Go to Step 23 | Go to Step 32 |
11 |
Did the TCC/Brake pedal switch parameter change state? | Go to Step 15 | Go to Step 12 |
12 |
Does the test lamp illuminate? | Go to Step 13 | Go to Step 14 |
13 |
Does the test lamp illuminate? | Go to Step 27 | Go to Step 25 |
14 |
Does the test lamp illuminate? | Go to Step 26 | Go to Step 33 |
15 | Is the vehicle equipped with a manual transmission? | Go to Step 16 | Go to Step 39 |
16 |
Did the CPP switch parameter change state? | Go to Step 39 | Go to Step 18 |
17 |
Does the test lamp illuminate? | Go to Step 19 | Go to Step 29 |
18 |
Does the test lamp illuminate? | Go to Step 28 | Go to Step 34 |
19 | Test the cruise control ON switch signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 45 | Go to Step 37 |
20 |
Important: On vehicles equipped with upfitter equipment, the upfitter wiring harness must be tested. Test the cruise control Set/Coast signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 45 | Go to Step 37 |
21 |
Important: On vehicles equipped with upfitter equipment, the upfitter wiring harness must be tested. Test the cruise control Resume/Accelerate signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 45 | Go to Step 37 |
22 | Test the stop lamp switch signal circuit between the stop lamp switch and the interface module for a short to battery positive. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 45 | Go to Step 35 |
23 | Test the stop lamp switch signal circuit between the stop lamp switch and the interface module for a 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 45 | Go to Step 35 |
24 | Test the stop lamp switch signal circuit between the TAC module and stop lamp interface module for a open, high resistance, short to ground 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 45 | Go to Step 38 |
25 | Test the TCC/Brake switch signal circuit between the PCM and stop lamp interface module for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 45 | Go to Step 38 |
26 | Test the brake switch signal circuit for a open, high resistance or short to battery positive. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 45 | Go to Step 35 |
27 | Test the brake switch signal 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 45 | Go to Step 35 |
28 | Test the CPP switch signal circuit for a open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 45 | Go to Step 36 |
29 |
Important: On vehicles equipped with upfitter equipment, the ignition positive voltage circuit to the PTO switch must be tested. Repair the open, high resistance or short to ground in the multifunction turn signal lever ignition positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 45 | -- |
30 | Repair the open, high resistance or short to ground in the stop lamp interface module ignition positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 45 | -- |
31 | Repair the open, high resistance or short to battery positive in the stop lamp interface module ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 45 | -- |
32 |
Important: On vehicles equipped with upfitter equipment, all stop lamp switch ignition positive voltage circuits must be tested. Repair the open, high resistance or short to ground in the stop lamp switch battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 45 | -- |
33 | Repair the open, high resistance or short to voltage in the stop lamp switch ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 45 | -- |
34 | Repair the open, high resistance or short to ground in the CPP switch battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 45 | -- |
35 | 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 45 | Go to Step 40 |
36 | Inspect for poor connections at the harness connector of the CPP 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 45 | Go to Step 41 |
37 | Inspect for poor connections at the harness connector of the multifunction turn signal lever. 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 45 | Go to Step 42 |
38 | Inspect for poor connections at the harness connector of the stop lamp interface 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 45 | Go to Step 43 |
39 | 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 45 | Go to Step 44 |
40 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Did you complete the repair? | Go to Step 45 | -- |
41 | Replace the CPP switch. Refer to Clutch Pedal Position Switch Replacement in Clutch. Did you complete the repair? | Go to Step 45 | -- |
42 | Replace the multifunction turn signal lever. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column. Did you complete the repair? | Go to Step 45 | -- |
43 | Replace the stop lamp switch interface module. Refer to Stop Lamp Interface Module Replacement Did you complete the repair? | Go to Step 45 | |
44 |
Important: The PCM must be reprogrammed before replacement. Refer to Powertrain Control Module Programming in Engine Controls. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls. | Go to Step 45 | -- |
45 | Operate the vehicle with in the conditions for cruise control operation. Does the cruise control system operate properly? | System OK | Go to Step 2 |
