Diagnostic Aids
In order to avoid misdiagnosis:
| • | Inspect for proper operation of the brake lamps. |
| • | Visually inspect all fuses relative to the cruise control system. |
| • | Inspect all connectors for poor terminal retention, corrosion or damage. |
| • | Inspect the throttle linkage/cable for mechanical binding. |
| • | Inspect cruise control cable adjustment. |
| • | EMI on the speed sensor signal circuit may cause erratic operation. |
PCM/VCM Inhibit
The PCM/VCM will inhibit cruise control if one or more of the following has occurred:
| • | When Park, Reverse, Neutral, or 1st gear is indicated. |
| • | When certain diagnostic trouble codes (DTC) are stored, refer to the appropriate DTCs in the Service Manual. |
| • | When an over/undercharged battery condition exists. |
| • | With low engine RPM. |
| • | With high engine RPM e.g. Fuel Cut-Off. |
The Cruise Control Tester
It has been found that when this Tester is used on some vehicles with high resistance or an open in the cruise control module ground circuit, the Tester's LEDs will light abnormally. For example, the Brake/Clutch and VSS LEDs will light normally but the Ignition LED will be dim with the ON/OFF switch in the OFF position. However, with the ON/OFF switch in the ON position only the VSS LED will light. If you come upon the above situation, please check the ground circuit prior to going on with your diagnosis.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform A Diagnostic System Check - Cruise Control? | Go to Step 2 | |
2 |
Is the IGNITION LED on the J 42958 illuminated? | Go to Step 3 | Go to Step 19 |
3 | Is the BRAKE/TCC LED on the J 42958 illuminated? | Go to Step 4 | Go to Step 21 |
4 | Press and release the brake pedal or clutch pedal, if equipped. Did the BRAKE/TCC LED turn OFF on the J 42958 | Go to Step 5 | Go to Step 23 |
5 | Place the cruise control On/Off switch in the ON position. Did the ON/OFF and the INHIBIT/ENABLE LED on the J 42958 illuminate? | Go to Step 6 | Go to Step 25 |
6 | Is the CRUISE LAMP LED on the J 42958 illuminated? | Go to Step 7 | Go to Step 26 |
7 | Press and release the Set/Coast switch. Did the SET/COAST LED on the J 42958 illuminate when the Set/Coast switch was pressed, and turn off when the Set/Coast switch was released? | Go to Step 8 | Go to Step 28 |
8 | Press and release the Resume/Accel switch. Did the RESUME/ACC LED on the J 42958 illuminate when the Resume/Accel switch was pressed, and turn off when the Resume/Accel switch was released? | Go to Step 9 | Go to Step 29 |
9 | Perform the following sequence:
Did the CRUISE ENGAGE LED illuminate continually after the S/C button was pressed and released? | Go to Step 10 | Go to Step 19 |
10 |
Did the throttle move to near wide open and then return approximately to half throttle when the R/A button on the J 42958 was released? | Go to Step 11 | Go to Step 33 |
11 |
Did the throttle move toward closed throttle and then return to approximately half throttle when the S/C button on the J 42958 was released? | Go to Step 12 | Go to Step 33 |
12 |
Did the CRUISE ENGAGE LED on the J 42958 turn off and the throttle return to the closed position? | Go to Step 13 | Go to Step 33 |
13 |
Did the VSS LED flash while the one drive wheel was rotated? | Go to Step 14 | Go to Step 31 |
14 | Does the connector harness of the cruise control module have a wire connected to terminal H? | Go to Step 15 | Go to Step 18 |
15 |
While observing the INHIBIT ENABLE LED of the J 42958 , use the scan tool in order to enable the cruise control. Did the INHIBIT ENABLE LED on the J 42958 dim when the scan tool was used to enable cruise control? | Go to Step 16 | Go to Step 30 |
16 |
Does the scan tool display enabled above 40 km/h (25 mph)? | Go to Step 16 | Go to Powertrain On Board Diagnostic (OBD) System Check or Powertrain On Board Diagnostic (OBD) System Check or Powertrain On Board Diagnostic (OBD) System Check in Engine Controls |
17 | Did the cruise control set and operate normally? | Go to Diagnostic Aids | Go to Step 33 |
18 |
Does cruise control operate normally? | Go to Diagnostic Aids | Go to Step 33 |
19 | Test for an open, high resistance or short to ground in the ignition voltage circuit of the cruise control module. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 20 |
20 | Test for a high resistance or the open in the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 33 |
21 | Inspect the brake/TCC and/or clutch switch if equipped for proper adjustment. Did you find and correct the condition? | Go to Step 36 | Go to Step 22 |
22 | Test for a open or the short to ground in the cruise release input circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 32 |
23 | Test for a short to voltage in the cruise release switch input circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 32 |
24 | Test for an open or high resistance in the stop lamp input circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 32 |
25 | Test for an open or the short to ground in the cruise control ON/OFF input circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 34 |
26 | Disconnect the J 42958 from the cruise control module, but leave the vehicle harness connected to the J 42958 . Did the CRUISE LAMP LED remain OFF when the cruise control module was disconnected? | Go to Step 27 | Go to Step 33 |
27 | Test for an open or short to ground in the cruise engaged output circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 34 |
28 | Test for an open or short to ground in the Set/Coast input circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 34 |
29 | Test for an open or short to voltage in the Resume/Accel input circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 34 |
30 | Test for an open or high resistance in the cruise inhibit circuit between the cruise control module and the PCM/VCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 35 |
31 | Test for an open or high resistance in the vehicle speed signal circuit between the cruise control module and the PCM/VCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 36 | Go to Step 35 |
32 | Replace the brake/TCC, and/or clutch if equipped switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Did you complete the replacement? | Go to Step 36 | -- |
33 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | Go to Step 36 | -- |
34 | Replace the cruise control switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column - Tilt. Did you complete the replacement? | Go to Step 36 | -- |
35 |
Important: The PCM/VCM must be reprogrammed after replacement. Refer to Powertrain Control Module Replacement/Programming or Powertrain Control Module Replacement/Programming or VCM Replacement/Programming in Engine Controls Did you complete the replacement? | Go to Step 36 | -- |
36 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | System OK | Go to Step 2 |
