Diagnostic Aids
To avoid misdiagnosis, inspect for the following:
| • | Proper operation of brake lamps. Refer to Exterior Lighting Systems Description and Operation in Lighting Systems. |
| • | Proper operation of the clutch system, if equipped. Refer to Clutch System Description and Operation in Clutch. |
| • | The throttle linkage is not binding. |
EMI on the vehicle 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). |
| • | The vehicle is not in PARK, REVERSE, NEUTRAL, or 1st gear. |
| • | The system voltage is within 9 volts and 16 volts. |
Step | Action | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Cruise Control Schematics | |||||||||
1 | Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | |||||||
2 |
Does the test lamp illuminate? | Go to Step 3 | Go to Step 5 | ||||||
3 | Connect a test lamp between the ignition 3 voltage circuit and the ground circuit of the cruise control module. Does the test lamp illuminate? | Go to Step 4 | Go to Step 24 | ||||||
4 |
Does the test lamp illuminate for any of the signal circuits listed above? | Go to Step 13 | Go to Step 6 | ||||||
5 |
Does the test lamp illuminate for any of the signal circuits listed above? | Go to Step 14 | Go to Step 22 | ||||||
6 |
Does the test lamp illuminate? | Go to Step 7 | Go to Step 15 | ||||||
7 |
Does the test lamp illuminate? | Go to Step 8 | Go to Step 17 | ||||||
8 |
Does the test lamp illuminate? | Go to Step 9 | Go to Step 18 | ||||||
9 | Is the vehicle equipped with a manual transmission? | Go to Step 11 | Go to Step 10 | ||||||
10 | Connect a test lamp between the TCC brake switch/Cruise control release signal circuit and a good ground. Refer to Circuit Testing in Wiring Systems. Does the test lamp illuminate? | Go to Step 12 | Go to Step 23 | ||||||
11 | Connect a test lamp between the clutch start switch signal circuit and a good ground. Refer to Circuit Testing in Wiring Systems. Does the test lamp illuminate? | Go to Step 12 | Go to Step 20 | ||||||
12 | Connect a test lamp between the cruise control engaged signal circuit and a good ground. Refer to Circuit Testing in Wiring Systems. Does the test lamp illuminate? | Go to Step 28 | Go to Step 19 | ||||||
13 | Test the signal circuit that illuminated the test lamp for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 27 | ||||||
14 | Test the signal circuit that illuminated the test lamp for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 27 | ||||||
15 | Test the cruise control on/off switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 16 | ||||||
16 | Test the ignition 3 voltage circuit for an open or for a high resistance between S204 and the multifunction switch. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 27 | ||||||
17 | Test the cruise control set/coast switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 27 | ||||||
18 | Test the cruise control resume/accel switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 27 | ||||||
19 | Test the cruise control engaged signal circuit for an open, for a high resistance, or for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 26 | ||||||
20 | Test the clutch start switch signal circuit for an open or for a high resistance between the clutch start switch and the cruise control module. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 21 | ||||||
21 | Test the TCC brake switch/Cruise control release signal circuit for an open or for a high resistance between S 138 and the clutch start switch. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 25 | ||||||
22 | Repair the open, the high resistance, or the short to ground in the ignition 3 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 33 | -- | ||||||
23 | Repair the open or the high resistance in the TCC brake switch/Cruise control release signal circuit between S 138 and the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 33 | -- | ||||||
24 | Repair the open or the high resistance in the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 33 | -- | ||||||
25 | Inspect for poor connections at the harness connector of the clutch start switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 30 | ||||||
26 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 29 | ||||||
27 | Inspect for poor connections at the harness connector of the multifunction switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 31 | ||||||
28 | Inspect for poor connections at the harness connector of the cruise control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 33 | Go to Step 32 | ||||||
29 |
Important: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.3L. Did you complete the replacement? | Go to Step 33 | -- | ||||||
30 | Replace the clutch start switch. Refer to Clutch Pedal Engine Start Switch Replacement in Clutch. Did you complete the replacement? | Go to Step 33 | -- | ||||||
31 | Replace the multifunction switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 33 | -- | ||||||
32 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | Go to Step 33 | -- | ||||||
33 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | System OK | Go to Step 2 | ||||||
