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 with a manual transmission. Refer to Clutch System Description and Operation in Clutch. |
| • | The throttle linkage is not binding. |
| • | The vehicle speed is greater than 40 km/h (25 mph). |
| • | The system voltage is within 9-16 volts. |
Electromagnetic interference on the vehicle speed sensor signal circuit may cause erratic cruise control operation.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views or Powertrain Control Module Connector End Views in Engine Controls - 4.3L | ||||||||||
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 31 | ||||||
4 |
Does the test lamp illuminate for any of the signal circuits listed above? | -- | Go to Step 16 | Go to Step 6 | ||||||
5 |
Does the test lamp illuminate for any of the signal circuits listed above? | -- | Go to Step 17 | Go to Step 29 | ||||||
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 18 | ||||||
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 20 | ||||||
8 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 21 | ||||||
9 |
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 32 | ||||||
10 | Is the vehicle equipped with a manual transmission? | -- | Go to Step 12 | Go to Step 11 | ||||||
11 | 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 13 | Go to Step 30 | ||||||
12 | 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 13 | Go to Step 23 | ||||||
13 | Connect a DMM between the cruise control engaged signal circuit and a good ground. Refer to Circuit Testing in Wiring Systems. Does the DMM display near the specified voltage? | B+ | Go to Step 14 | Go to Step 22 | ||||||
14 | Connect a DMM between the vehicle speed signal circuit and a good ground. Refer to Circuit Testing in Wiring Systems. Does the DMM display near the specified voltage? | B+ | Go to Diagnostic Aids | Go to Step 15 | ||||||
15 | Test the vehicle speed 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 37 | Go to Step 28 | ||||||
16 | 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 37 | Go to Step 27 | ||||||
17 | 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 37 | Go to Step 27 | ||||||
18 | 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 37 | Go to Step 19 | ||||||
19 | Test the ignition 3 voltage circuit for an open or for a high resistance between SP 200 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 37 | Go to Step 27 | ||||||
20 | 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 37 | Go to Step 27 | ||||||
21 | 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 37 | Go to Step 27 | ||||||
22 | 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 37 | Go to Step 26 | ||||||
23 | 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 37 | Go to Step 24 | ||||||
24 | Test the TCC brake switch/cruise control release signal circuit for an open or for a high resistance between the stop lamp switch 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 37 | Go to Step 25 | ||||||
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 37 | Go to Step 34 | ||||||
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 37 | Go to Step 33 | ||||||
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 37 | Go to Step 35 | ||||||
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 37 | Go to Step 36 | ||||||
29 | 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 37 | -- | ||||||
30 | 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 37 | -- | ||||||
31 | 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 37 | -- | ||||||
32 | Repair the open or the high resistance in the CHMSL supply voltage/stop lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 37 | -- | ||||||
33 |
Important: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.3 L. Did you complete the replacement? | -- | Go to Step 37 | -- | ||||||
34 | Replace the clutch start switch. Refer to Clutch Pedal Engine Start Switch Replacement in Clutch. Did you complete the replacement? | -- | Go to Step 37 | -- | ||||||
35 | Replace the multifunction switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 37 | -- | ||||||
36 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 37 | -- | ||||||
37 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 | ||||||
