Diagnostic Aids
Important: Perform the following in order to avoid misdiagnosis.
• Inspect for proper operation of the brake lamps. • Inspect for proper operation of the transmission range switch. • Inspect throttle linkage for mechanical binding which could cause
the system to malfunction. • Inspect cruise control cable adjustment, should have minimum slack. • Inspect for stored Diagnostic Trouble Codes. Refer to
Powertrain On Board Diagnostic (OBD) System Check
in
Engine Controls-4.6L. • EMI on the speed sensor signal circuit may cause erratic cruise
control operation.
Conditions for Enabling Cruise Control
| • | When vehicle speed is more than 40 km/h (25 mph) |
| • | When PARK, REVERSE, NEUTRAL, or 1st gear is not indicated by the Park / Neutral Position Switch. |
| • | When an over / undercharged battery condition does not exist. |
| • | With normal engine RPM. |
| • | Without high engine RPM (fuel cut-off). |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic:
| ||||
1 | Did you perform the Cruise Control Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Does the test lamp illuminate? | -- | Go to Step 3 | Go to Step 36 |
3 | Probe the ignition 1 voltage circuit of the cruise control module with a test lamp that is connected to the ground circuit of the cruise control module. Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 37 |
4 |
Does the test lamp illuminate on any of the circuits? | -- | Go to Step 16 | Go to Step 5 |
5 |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 17 |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 19 |
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 20 |
8 | Probe the ABS/TCC switch signal circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 21 |
9 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 22 | Go to Step 10 |
10 | Probe the stoplamp switch signal circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 23 | Go to Step 11 |
11 | Press the brake pedal while monitoring the test lamp. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 24 |
12 | Probe the cruise inhibit signal circuit with a test lamp that is connected to B+. Does the test lamp illuminate? | -- | Go to Step 25 | Go to Step 13 |
13 | Use a scan tool in order to command the cruise disable OFF. Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 26 |
14 | Probe the cruise engaged signal circuit with a DMM that is connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 15 | Go to Step 27 |
15 | Check the speedometer for proper operation. Does the speedometer operate properly? | -- | Go to Step 28 | |
16 | Test the signal circuit that illuminated the test lamp for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
17 | Test the on/off, resume /accel, set coast signal circuits for a open, high resistance or short to ground and the ABS/TCC switch ignition positive voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 18 |
18 | Test the ignition 1 voltage circuit of the cruise control switch for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
19 | Test the set/coast signal circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
20 | Test the resume/accel signal circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 34 |
21 | Test the ABS/TCC (cancel) signal circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 29 |
22 | Test the ABS/TCC (cancel) signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 29 |
23 | Test the stoplamp switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 30 |
24 | Test the stoplamp switch signal circuit for a open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 30 |
25 | Test the cruise inhibit signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 33 |
26 | Test the cruise inhibit signal circuit for a open, high resistance or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 33 |
27 | Test the cruise engaged output signal circuit for a open, high resistance or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 33 |
28 | Test the VSS signal circuit for a open or high resistance between the PCM and cruise control module. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 35 |
29 | Inspect the ABS/TCC switch for proper adjustment. Refer to Cruise Release Switch Adjustment . Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 31 |
30 | Inspect the stoplamp/automatic transmission shift lock control switch for proper adjustment. Refer to Stop Lamp Switch Adjustment in Hydraulic Brakes. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 32 |
31 | Inspect for poor connections at the harness connector of the ABS/TCC switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 38 |
32 | Inspect for poor connections at the harness connector of the stoplamp/automatic transmission shift lock control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 39 |
33 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 40 |
34 | Inspect for poor connections at the harness connector of the steering wheel controls. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 41 |
35 | Inspect for poor connections at the harness connector of the cruise control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 43 | Go to Step 42 |
36 | Repair the ignition 1 voltage circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 43 | -- |
37 | Repair the ground circuit of the cruise control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 43 | -- |
38 | Replace the ABS/TCC switch. Refer to Cruise Control Release Switch Replacement in Hydraulic Brakes. Did you complete the replacement? | -- | Go to Step 43 | -- |
39 | Replace the stoplamp/automatic transmission shift lock control switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Did you complete the replacement? | -- | Go to Step 43 | -- |
40 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls-4.6L. Did you complete the replacement? | -- | Go to Step 43 | -- |
41 | Replace the steering wheel controls. Refer to Steering Wheel Control Switch Assembly Replacement in Steering Wheel and Column - Tilt. Did you complete the replacement? | -- | Go to Step 43 | -- |
42 | Replace the cruise control module. Refer to Cruise Control Module Replacement . Did you complete the replacement? | -- | Go to Step 43 | -- |
43 | Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate correctly? | -- | System OK | Go to Step 2 |
