Diagnostic Aids
Important: Perform the following in order to avoid misdiagnosis.
• Inspect for proper operation of brake lamps and clutch switch,
if equipped. • Inspect throttle linkage for mechanical binding which could cause
the system to malfunction. • Inspect cruise control cable adjustment, should have minimum slack. • 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).
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Cruise Control Schematics | ||||
1 | Did you perform A Diagnostic System Check - Cruise Control? | -- | Go to Step 2 | |
2 |
Does the test lamp illuminate? | -- | Go to Step 3 | Go to Step 34 |
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. Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 35 |
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 stop lamp switch signal circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 24 | 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 25 |
10 | Probe the TCC/Brake, cruise release switch signal circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 11 |
11 | Is the vehicle equipped with a manual transmission? | -- | Go to Step 13 | Go to Step 21 |
12 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 23 | Go to Step 14 |
13 |
Does the test lamp illuminate? | -- | Go to Step 26 | Go to Step 21 |
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, Gauges 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 40 | Go to Step 31 |
17 | Test the cruise control on switch circuit for an open or a high resistance and the set/coast, resume/accel 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 40 | Go to Step 18 |
18 | Test the cruise control switch ignition positive voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 40 | Go to Step 31 |
19 | Test the cruise control set/coast 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 40 | Go to Step 31 |
20 | Test the cruise control resume/accelerate 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 40 | Go to Step 31 |
21 | Test the TCC/Brake, cruise release 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 40 | Go to Step 30 |
22 | Test the CPP switch ignition positive voltage 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 40 | Go to Step 30 |
23 | Test the TCC/Brake, 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 40 | Go to Step 30 |
24 | 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 40 | Go to Step 30 |
25 | 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 40 | Go to Step 30 |
26 | Test the CPP 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 40 | Go to Step 29 |
27 | Test the cruise engaged signal circuit for an open, a 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 40 | Go to Step 32 |
28 | Test the speed sensor circuit for an open or a high resistance between the PCM and cruise control module. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 40 | Go to Step 32 |
29 | 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 40 | Go to Step 36 |
30 | 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 40 | Go to Step 36 |
31 | 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 40 | Go to Step 37 |
32 | 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 40 | Go to Step 38 |
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 40 | Go to Step 39 |
34 | 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 40 | -- |
35 | Repair the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 40 | -- |
36 | Replace the appropriate switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes or Clutch Pedal Engine Start Switch Replacement in Clutch. Did you complete the replacement? | -- | Go to Step 40 | -- |
37 | Replace the multifunction turn signal lever. Refer to Turn Signal and Multifunction Switch Assembly - Disassemble - Off Vehicle in Steering Wheel and Column - Tilt. Did you complete the replacement? | -- | Go to Step 40 | -- |
38 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 40 | -- |
39 |
Important: The PCM must be reprogrammed before replacement. Refer to Powertrain Control Module Programming in Engine Controls-4.3L. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-4.3L. Did you complete the replacement? | -- | Go to Step 40 | -- |
40 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 |
