| Table 1: | Cruise Control Disengage Definitions |
| Table 2: | Cruise Control System Check |
Circuit Description
The Cruise Control system is a speed control system that maintains a desired vehicle speed under normal driving conditions. The cruise control system has the capability of the following:
| • | Cruise |
| • | Coast |
| • | Resume speed |
| • | Accelerate |
| • | Raise (Tap-up) the vehicle speed by 1.6 km/h (1 mph) |
| • | Lower (Tap-down) the vehicle speed by 1.6 km/h (1 mph) |
The Throttle Actuator Control (TAC) module controls the cruise system. When the cruise control switch is in the ON position and you push the cruise SET/COAST switch, the TAC module maintains the current vehicle speed. If the engine load varies, the TAC module commands the throttle blade to the appropriate position in order to maintain the desired vehicle speed.
The cruise control system consists of the following components:
| • | Throttle Actuator Control (TAC) Module |
| • | Throttle Actuator Control Motor |
| • | Cruise Control Actuator Lever |
Conditions for Enabling the Cruise System
| • | The Cruise switch is in the ON position. |
| • | Ignition voltage is present to the cruise actuator lever. |
| • | The vehicle speed is greater than 39 km/h (24 mph). |
| • | The brake pedal is not depressed. |
| • | The transmission is in a forward gear. |
| • | The engine is not in Engine Coolant Over Temperature-Fuel Disabled mode. |
| • | The cruise SET/COAST switch has been pushed and released. |
Conditions for Disabling the Cruise System
| • | The Cruise switch is turned to the OFF position. |
| • | Ignition voltage is interrupted to the cruise actuator lever. |
| • | The vehicle speed is less than 32 km/h (20 mph). |
| • | The brake pedal is depressed. |
| • | The engine is in Engine Coolant Over Temperature-Fuel Disabled mode. |
| • | The transmission is placed into neutral. |
| • | A problem with brake pedal switches or circuits that the TAC module interprets as the pedal is applied. |
Diagnostic Aids
Use the scan tool in order to monitor the Cruise Disengage History. This parameter lists the last 8 cruise disengage events. Refer to Cruise Disengage History table for a description of each condition.
The cruise control system disables for the current ignition cycle if an intermittent condition exists.
Scan Tool Display | Definition | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Accel (Acceleration) Rate | The vehicle acceleration is greater than the expected acceleration rate which is calculated by the PCM | ||||||||||||||
Brake Switches | The TAC module detects one of the brake switches active (TCC Brake Switch/Cruise Control Brake Switch or Stop Lamp Switch) | ||||||||||||||
Clutch Switch | The TAC module detects the clutch switch active | ||||||||||||||
Coast Speed Low | The Set/Coast switch is pushed and held until vehicle speed drops below 32 km/h (20 mph) Vehicle speed below 32 km/h (20 mph) will disable the cruise system. | ||||||||||||||
CC (Cruise Control) Switch Position | The TAC module will not allow cruise with the current position of the cruise switches | ||||||||||||||
Cruise Off | The TAC module does not detect that the cruise enable switch is active | ||||||||||||||
Decel (Deceleration) Rate | The vehicle deceleration is greater than the expected deceleration rate which is calculated by the PCM | ||||||||||||||
High Speed | The PCM detects that the vehicle speed is greater than 265 km/h (165 mph) | ||||||||||||||
Low Speed | The PCM detects that the vehicle speed is less than 39 km/h (24 mph) when cruise enable is attempted | ||||||||||||||
No History | The No History parameter is displayed when a battery disconnect occurs | ||||||||||||||
Over Set Speed | The TAC module detects that the vehicle speed is greater than the cruise memory speed by more than a predetermined amount or, the vehicle speed is greater than a predetermined value during a transient maneuver, such as, Resume, Accel, Tap-up or Tap-downs etc. | ||||||||||||||
Pedal Initialization | The PCM does not detect the brake or clutch switches active during an ignition cycle | ||||||||||||||
PCM Error | An internal PCM fault is detected | ||||||||||||||
PCM Inhibit | The PCM detects one of the following conditions:
| ||||||||||||||
S/C (Set/Coast) On, CC (Cruise Control) Off | The TAC module detects the Cruise Set/Coast signal is ON When the switch is pushed (Cruise Coast Mode), this parameter will be displayed. If a fault is present with the Cruise Set/Coast signal circuit, this parameter will be displayed. | ||||||||||||||
S/C On-Speed High | This parameter is displayed when the Set/Coast switch is applied (tap down vehicle speed) and the vehicle speed is greater than the cruise memory speed by more than a predetermined value. For example, if the cruise control system is set to maintain a vehicle speed of 48 km/h (30 mph) then the vehicle is accelerated to 80 km/h (50 mph) and you depress the Set/Coast again, the S/C On-Speed High message appears in the Cruise Control Disengage History | ||||||||||||||
TAC Inhibit | The TAC module has detected that an Electronic Throttle Control fault is active | ||||||||||||||
Traction Loss | The TAC module detects the vehicle is in a Traction Control event | ||||||||||||||
Two CC Commands | The TAC module detects the Set/Coast and Resume/Accel switches are active at the same time | ||||||||||||||
Under Set Speed | The TAC module detects that the vehicle speed is less than the cruise memory speed by more than a predetermined amount or, the vehicle speed is less than a predetermined value during a transient maneuver, such as, Resume, Accel, Tap-up or Tap-downs etc. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 | Are DTCs P0500, P0601, P0606, or any Throttle Actuator Control system faults set? | -- | Go to Applicable DTC Table | |
3 | Is the cruise control fuse open? | -- | ||
4 |
Does the scan tool display CC Brake Switch Applied when the brake pedal was pressed? | -- | Go to CC Brake switch Diagnosis | |
5 | Monitor the Cruise Switch parameter on the Cruise Control data list using the scan tool. Does the scan tool display Cruise Switch on? | -- | ||
6 |
Does the scan tool display Cruise Set/Coast ON when the switch was pushed in? | -- | ||
7 |
Does the scan tool display Cruise Resume/Accel as ON when the switch was pushed in? | -- | System OK | |
8 |
Does the test lamp illuminate? | -- | ||
9 | Probe the cruise ON/OFF signal circuit (TAC side of the circuit) using a test lamp J 35616-200 connected to B+. Does the test lamp illuminate? |
-- | ||
10 | Test lamp still connected to the cruise ON/OFF signal circuit (TAC side of the circuit), disconnect the appropriate TAC module connector. Did the test lamp go OFF when the TAC module was disconnected? | -- | ||
11 |
Did the fuse open when the switch was pushed in? | -- | ||
12 | Push the Cruise Resume/Accel switch ON. Did the fuse open when the switch was pushed in? | -- | Intermittent short to ground. Go to Diagnostic Aids | |
13 | Repair the grounded circuit between the TAC module and the Cruise Control Lever. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
14 |
Does the test lamp illuminate? | -- | ||
15 | Using a fused jumper wire connected to B+, probe the cruise ON/OFF signal circuit (TAC module side of the circuit) and monitor the Cruise Switch parameter. Does the scan tool display Cruise Switch on? | -- | ||
16 |
Is continuity indicated on the DMM? | -- | ||
17 | Repair the Cruise ON/OFF signal circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
18 |
Does the scan tool display the Cruise Set/Coast parameter as ON when the voltage was applied? | -- | ||
19 |
Is continuity indicated on the DMM? | -- | ||
20 | Repair the Cruise Set/Coast signal circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
21 |
Does the scan tool display the Cruise Resume/Accel parameter as ON when the voltage was applied? | -- | ||
22 |
Is continuity indicated on the DMM? | -- | ||
23 | Repair the Cruise Resume/Accel signal circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
24 | Repair the open circuit between the Cruise Control Lever and the fuse block. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
25 |
Is the action complete? | -- | System OK | -- |
26 |
Did you find a problem and correct it? | -- | System OK | |
27 | Replace the Cruise Control Lever (multi-function lever). Refer to Steering/Steering Wheel and Column. Is the action complete? | -- | System OK | -- |
28 |
Did you find a problem and correct it? | -- | System OK | |
29 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Is the action complete? | -- | System OK | -- |
30 |
Is the action complete? | -- | System OK | -- |
