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. • 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 |
|---|---|---|---|---|
1 | Did you review the cruise control operation and perform the necessary inspections? | -- | Go to Step 2 | Go to Symptoms |
2 | Verify that the cruise control is inoperative or malfunctioning. Does the cruise control operate normally? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
3 |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 33 |
4 | 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 5 | Go to Step 34 |
5 |
Does the test lamp illuminate on any of the circuits? | -- | Go to Step 15 | Go to Step 6 |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 16 |
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 18 |
8 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 19 |
9 | Probe the brake circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 20 |
10 | Depress the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 21 | Go to Step 11 |
11 | Probe the cruise release circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 22 | Go to Step 12 |
12 | Depress the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 13 | Go to Step 23 |
13 | 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 14 | Go to Step 24 |
14 |
Does the voltage displayed on the DMM vary? | -- | Go to Step 32 | Go to Step 25 |
15 | 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 39 | Go to Step 31 |
16 | Test the on/off 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 39 | Go to Step 17 |
17 | Test the ignition positive voltage circuit for an open or high resistance between the cruise control module and the cruise control switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 39 | Go to Step 31 |
18 | Test the set/coast 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 39 | Go to Step 31 |
19 | Test the resume/accelerate 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 39 | Go to Step 31 |
20 | Test the brake 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 39 | Go to Step 26 |
21 | Test the brake 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 39 | Go to Step 26 |
22 | Test the cruise release 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 39 | Go to Step 27 |
23 | Test the cruise release 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 39 | Go to Step 27 |
24 | Test the cruise engaged output circuit for an open, a high resistance, 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 39 | Go to Step 30 |
25 | Test the speed sensor 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 39 | Go to Step 30 |
26 | Inspect the brake switch for proper adjustment. Did you find and correct the condition? | -- | Go to Step 39 | Go to Step 28 |
27 | Inspect the brake switch for proper adjustment. Did you find and correct the condition? | -- | Go to Step 39 | Go to Step 29 |
28 | Inspect for poor connections at the harness connector of the brake 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 39 | Go to Step 35 |
29 | Inspect for poor connections at the harness connector of the brake 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 39 | Go to Step 35 |
30 | Inspect for poor connections at the harness connector of the VCM. 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 39 | 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 39 | 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 39 | Go to Step 38 |
33 | 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 39 | -- |
34 | Repair the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 39 | -- |
35 | Replace the brake switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Did you complete the replacement? | -- | Go to Step 39 | -- |
36 | Replace the PCM/VCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls -- 2.2L or VCM Replacement/Programming in Engine Controls -- 4.3L. Did you complete the replacement? | -- | Go to Step 39 | -- |
37 | Replace the multifunction switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 39 | -- |
38 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 39 | -- |
39 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 3 |
