Diagnostic Aids
Caution: Refer to SIR Caution in the Preface section.
Disable the inflatable restraint steering wheel module when performing this diagnostic table. Refer to SIR Disabling and Enabling in SIR.
Perform the following in order to avoid misdiagnosis:
| • | Ensure that the following cruise control switches are not stuck in the engaged position: |
| - | On/Off switch |
| - | Set/Coast switch |
| - | Resume/Accel switch |
| • | Inspect for proper operation of the stop lamps. Refer to Exterior Lighting Systems Description and Operation in Wiring Systems. |
| • | Rotate the steering wheel to both steering stops and activate each cruise control switch separately. With a scan tool, observe the associated Cruise Control Switch parameter in the PCM Cruise Control Data data list. This will help eliminate the possibility of a internally open or shorted inflatable restraint steering wheel module coil. |
| • | EMI on the speed sensor signal circuit may cause erratic cruise control operation. |
| • | For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The number below refers to the step number on the diagnostic path.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Cruise Control Schematics Connector End View Reference: Powertrain Control Module Connector End Views in Engine Controls - 3.8L (L26 and L32) | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||
2 | Is DTC P0573 current in the powertrain control module (PCM)? | -- | Go to DTC P0573 in Lighting Systems | Go to Step 3 | ||||||
3 |
Do any of the parameters listed above display On? | -- | Go to Step 13 | Go to Step 4 | ||||||
4 |
Does the Cruise On/Off Switch parameter display On? | -- | Go to Step 5 | Go to Step 14 | ||||||
5 |
Does the Cruise Set/Coast Switch parameter display On? | -- | Go to Step 6 | Go to Step 21 | ||||||
6 |
Does the Cruise Resume/Accel Switch parameter display On? | -- | Go to Step 7 | Go to Step 21 | ||||||
7 |
Does the voltage measure at or greater than the specified voltage? | 0.5 V | Go to Step 12 | Go to Step 8 | ||||||
8 |
Does the voltage measure at the specified voltage? | B+ | Go to Step 9 | Go to Step 20 | ||||||
9 |
Does the voltage measure greater than the specified value? | 8.5 V | Go to Step 10 | Go to Step 17 | ||||||
10 | Test the vehicle speed signal circuit 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 29 | Go to Step 11 | ||||||
11 | With a DMM, measure the voltage of the stop lamp switch signal circuit. Does the voltage measure greater than the specified value? | 8.5 V | Go to Step 23 | Go to Step 24 | ||||||
12 | Test the cruise control cancel signal circuit 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 29 | Go to Step 21 | ||||||
13 |
Do any of the parameters listed above display On? | -- | Go to Step 18 | Go to Step 21 | ||||||
14 |
Does the test lamp illuminate? | -- | Go to Step 15 | Go to Step 25 | ||||||
15 | Test the ignition 1 voltage circuit for an open or for a high resistance between C201 and the cruise control switch. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 29 | Go to Step 16 | ||||||
16 |
Does the Cruise Mode Signal parameter display at or greater than the specified voltage? | 4.5 V | Go to Step 21 | Go to Step 19 | ||||||
17 | 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 29 | Go to Step 22 | ||||||
18 | Test the cruise control set/coast and resume/accel switch signal circuit 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 29 | Go to Step 22 | ||||||
19 | Test the cruise control set/coast and resume/accel switch signal circuit for an open, for a short to ground, 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 29 | Go to Step 22 | ||||||
20 | Test the cruise control cancel signal circuit for a short to ground, 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 29 | Go to Step 21 | ||||||
21 | Inspect for poor connections at the harness connector of the cruise control 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 29 | Go to Step 26 | ||||||
22 | 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 29 | Go to Step 28 | ||||||
23 | Inspect for poor connections at the harness connector of the TAC 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 29 | Go to Step 27 | ||||||
24 | Repair the open or the high resistance in the stop lamp switch signal circuit between the underhood fuse block and the TAC module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 29 | -- | ||||||
25 | Repair the open, the short to ground, or the high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 29 | -- | ||||||
26 | Replace the cruise control switch. Refer to Cruise Control Switch Replacement . Did you complete the replacement? | -- | Go to Step 29 | -- | ||||||
27 | Replace the TAC module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 29 | -- | ||||||
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 29 | -- | ||||||
Does the cruise control system operate properly? | -- | System OK | Go to Step 2 | |||||||
