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. |
| • | 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 Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
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 26 | ||||||
4 |
Does the test lamp illuminate for any of the signal circuits listed above? | -- | Go to Step 14 | Go to Step 6 | ||||||
5 |
Does the test lamp illuminate for any of the signal circuits listed above? | -- | Go to Step 15 | Go to Step 24 | ||||||
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 |
Does the test lamp illuminate? | -- | Go to Step 10 | Go to Step 27 | ||||||
10 | Connect a test lamp between the torque converter clutch (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 11 | Go to Step 25 | ||||||
11 | 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 12 | Go to Step 20 | ||||||
12 | 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 13 | ||||||
13 | 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 31 | Go to Step 23 | ||||||
14 | 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 31 | Go to Step 22 | ||||||
15 | 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 31 | Go to Step 22 | ||||||
16 | 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 31 | Go to Step 17 | ||||||
17 | Test the ignition 3 voltage circuit for an open or for a high resistance between SP 201 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 31 | Go to Step 22 | ||||||
18 | 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 31 | Go to Step 22 | ||||||
19 | 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 31 | Go to Step 22 | ||||||
20 | 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 31 | Go to Step 21 | ||||||
21 | Inspect for poor connections at the harness connector of the powertrain control module (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 31 | Go to Step 28 | ||||||
22 | 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 31 | Go to Step 29 | ||||||
23 | 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 31 | Go to Step 30 | ||||||
24 | 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 31 | -- | ||||||
25 | Repair the open or the high resistance in the TCC brake switch/cruise control release signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 31 | -- | ||||||
26 | 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 31 | -- | ||||||
27 | Repair the open or the high resistance in the stop lamp switch signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 31 | -- | ||||||
28 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 31 | -- | ||||||
29 | Replace the multifunction switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 31 | -- | ||||||
30 | Replace the cruise control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 31 | -- | ||||||
31 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 | ||||||
