Diagnostic Aids
To avoid misdiagnosis, inspect for the following:
| • | Proper operation of the brake lamps. Refer to Exterior Lighting Systems Description and Operation in Lighting Systems. |
| • | The throttle linkage is not binding. |
| • | The cruise control release switch is adjusted properly. Refer to Torque Converter Clutch/Cruise Control Release Switch Adjustment in Automatic Transaxle - 4T65-E. |
| • | The stoplamp switch is adjusted properly. Refer to Stop Lamp Switch Adjustment in Hydraulic Brakes. |
EMI on the vehicle speed sensor signal circuit may cause erratic cruise control operation.
Conditions for Enabling Cruise Control
| • | The vehicle speed is greater than 40 km/h (25 mph) |
| • | The vehicle is not in PARK, REVERSE, NEUTRAL, or 1st gear. |
| • | The system voltage is within 9 volts and 16 volts. |
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Cruise Control Diagnostic System Check? | -- | Go to Step 2 | |||||||
2 |
Does the speedometer operate properly? | -- | Go to Step 3 | Go to Symptoms - Instrument Panel, Gages and Console in Instrument Panel Gages and Console | ||||||
3 |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 27 | ||||||
4 |
Does the test lamp illuminate for any of the signal circuits listed above? | -- | Go to Step 12 | Go to Step 5 | ||||||
5 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 13 | ||||||
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 15 | ||||||
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 16 | ||||||
8 | Connect a test lamp between the cruise control release signal circuit and a good ground. Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 17 | ||||||
9 | Apply the brake pedal. Does the test lamp remain illuminated? | -- | Go to Step 19 | Go to Step 10 | ||||||
10 | Measure the voltage at the cruise control engaged circuit. Does the voltage measure near the specified value? | B+ | Go to Step 11 | Go to Step 21 | ||||||
11 | Do the stop lamps operate properly? | -- | Go to Step 20 | Go to Diagnostic System Check - Lighting Systems in Lighting Systems | ||||||
12 | Test the suspected 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 32 | Go to Step 25 | ||||||
13 | Test the cruise control on 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 32 | Go to Step 14 | ||||||
14 | Test the ignition 3 voltage circuit of the cruise control on/off switch 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 32 | Go to Step 25 | ||||||
15 | 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 32 | Go to Step 25 | ||||||
16 | 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 32 | Go to Step 25 | ||||||
17 | Test the cruise control release 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 32 | Go to Step 18 | ||||||
18 | Test the ignition 3 voltage circuit of the cruise control release switch for an open, for a short to ground, or for high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 23 | ||||||
19 | Test the cruise control release 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 32 | Go to Step 23 | ||||||
20 | Test the stop lamp switch signal circuit of the cruise control module for an open, for a high resistance, or 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 32 | Go to Step 22 | ||||||
21 | 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 32 | Go to Step 24 | ||||||
22 | Test the vehicle speed signal circuit for an open or for a high resistance between the cruise control module and S217. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 26 | ||||||
23 | Inspect for poor connections at the harness connector of the cruise control release 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 32 | Go to Step 28 | ||||||
24 | 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 32 | Go to Step 29 | ||||||
25 | Inspect for poor connections at the harness connector of the turn signal/multifunction lever (Monte Carlo) or of the steering wheel control switch assembly (Impala). 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 32 | Go to Step 30 | ||||||
26 | 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 32 | Go to Step 31 | ||||||
27 | Repair the open in the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 32 | -- | ||||||
28 | Replace the cruise control release switch. Refer to Torque Converter Clutch/Cruise Control Release Switch Replacement in Automatic Transaxle - 4T65-E. Did you complete the replacement and the adjustment? | -- | Go to Step 32 | -- | ||||||
29 |
Important: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 3.4L or to DTC P0172 in Engine Controls - 3.8L. Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||
30 | Replace the turn signal/multifunction switch lever or the steering wheel control switch assembly. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column or to Steering Wheel Control Switch Assembly Replacement in Steering Wheel and Column. Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||
31 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- | ||||||
32 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 |
