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 Inhibit
The PCM inhibits the cruise control if one or more of the following has occurred:
| • | When the park/neutral switch indicates park, reverse, neutral, or first gear. |
| • | When certain Diagnostic Trouble Codes (DTC) are stored. Refer to the appropriate DTC(s) in the Service Manual. |
| • | When an over/undercharged battery condition exists. |
| • | With low engine RPM. |
| • | With high engine RPM (Fuel Cut-Off). |
The Cruise Control Tester
When this tester is used on some vehicles with high resistance or with an open in the cruise control module ground circuit, the tester's LEDs will light abnormally. For example, the Brake/Clutch and VSS LED(s) 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 encounter this situation, please inspect the ground circuit prior to continuing with your diagnosis.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cruise Control Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Is the IGNITION LED on the J 42958 illuminated? | -- | Go to Step 3 | Go to Step 20 |
3 | Is the BRAKE/TCC LED on the J 42958 illuminated? | -- | Go to Step 4 | Go to Step 22 |
4 | Is the BRAKE LIGHTS LED on the J 42958 OFF? | -- | Go to Step 5 | Go to Step 23 |
5 | Press and release the brake pedal. Did the BRAKE/TCC LED turn OFF on the J 42958 when each step was performed? | -- | Go to Step 6 | Go to Step 25 |
6 | Place the cruise control On/Off switch in the ON position. (Leave this switch on until you have completed the diagnostic procedure.) Did the ON/OFF and the INHIBIT/ENABLE LED on the J 42958 illuminate? | -- | Go to Step 7 | Go to Step 27 |
7 | Is the CRUISE LAMP LED on the J 42958 illuminated? | -- | Go to Step 8 | Go to Step 28 |
8 | Press and release the Set/Coast switch. Did the SET/COAST LED on the J 42958 illuminate when you pressed the Set/Coast switch, and turn off when you released the Set/Coast switch? | -- | Go to Step 9 | Go to Step 31 |
9 | Press and release the Resume/Accel switch. Did the RESUME/ACC LED on the J 42958 illuminate when you pressed the Resume/Accel switch, and turn off when you released the Resume/Accel switch? | -- | Go to Step 10 | Go to Step 32 |
10 | Perform the following sequence:
Did the CRUISE ENGAGE LED illuminate continually after you pressed and released the S/C button? | -- | Go to Step 11 | Go to Step 20 |
11 |
Did the throttle move to near wide open, and then return approximately to half throttle when you pressed the R/A button on the J 42958 ? | -- | Go to Step 12 | Go to Step 36 |
12 |
Did the throttle move toward closed throttle, and then return to approximately half throttle when the you released S/C button on the J 42958 ? | -- | Go to Step 13 | Go to Step 36 |
13 |
Did the CRUISE ENGAGE LED on the J 42958 turn off and the throttle return to the closed position? | -- | Go to Step 14 | Go to Step 36 |
14 |
Did the VSS LED flash while you rotated the one drive wheel? | -- | Go to Step 15 | Go to Step 29 |
15 | Does the connector harness of the cruise control module have a wire connected to terminal H? | -- | Go to Step 16 | Go to Step 19 |
16 |
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 17 | Go to Step 33 |
17 |
Does the scan tool display enabled above 40 km/h (25 mph)? | -- | Go to Step 18 | Go to DTC P1585 Cruise Control Inhibit Output Circuit 3.1L in Engine Controls or DTC P1585 Cruise Control Inhibit Output Circuit 3.8L in Engine Controls |
18 | Did the cruise control set and operate normally? | -- | Go to Diagnostic Aids | Go to Step 36 |
19 |
Does the cruise control operate correctly? | -- | Go to Diagnostic Aids | Go to Step 36 |
20 | Test for an open, a high resistance or a 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 39 | Go to Step 21 |
21 | Repair the 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 39 | Go to Step 36 |
22 | Inspect the cruise control release switch for proper adjustment. Refer to Cruise Release Switch Adjustment . Did you find and correct the condition? | -- | Go to Step 39 | Go to Step 24 |
23 | Inspect the stop lamp switch for proper adjustment. Refer to Stop Lamp Switch Adjustment . Did you find and correct the condition? | -- | Go to Step 39 | Go to Step 26 |
24 | Repair the 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 39 | Go to Step 34 |
25 | Repair the 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 39 | Go to Step 34 |
26 | Repair the 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 39 | Go to Step 35 |
27 | Repair the 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 39 | Go to Step 37 |
28 | 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 you disconnected the cruise control module? | -- | Go to Step 30 | Go to Step 36 |
29 | Test for an open or a short to ground or a short to B+ in the vehicle speed signal input circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 39 | Go to Step 38 |
30 | 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 39 | Go to Step 38 |
31 | 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 39 | Go to Step 37 |
32 | Test for an open or a 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 39 | Go to Step 37 |
33 | Test for an open or high resistance in the cruise inhibit circuit between the cruise control module and the PCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 39 | Go to Step 38 |
34 | Replace the cruise control release switch. Refer to Cruise Control Release Switch Replacement and Cruise Release Switch Adjustment . Did you complete the replacement? | -- | Go to Step 39 | -- |
35 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement and Stop Lamp Switch Adjustment . Did you complete the replacement? | -- | Go to Step 39 | -- |
36 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 39 | -- |
37 | Replace the cruise control switch. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle . Did you complete the replacement? | -- | Go to Step 39 | -- |
38 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming 3.1L or Powertrain Control Module Replacement/Programming 3.8L in Engine Controls. 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 2 |
