| 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 PCM controls the cruise system. When the cruise control switch is in the ON position and you push the cruise SET/COAST switch, the PCM maintains the current vehicle speed. If the engine load varies, the PCM commands the throttle blade to the appropriate position in order to maintain the desired vehicle speed. The TAC Module sends all cruise control requests to the PCM via the serial data circuit.
The cruise control system consists of the following components:
| • | The Powertrain Control Module (PCM) |
| • | The Throttle Actuator Control (TAC) Module |
| • | The Throttle Actuator Control Motor |
| • | The 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 clutch or brake pedal is not depressed. |
| • | The transmission is in a forward gear. |
| • | The vehicle is not in a traction control event. |
| • | 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 clutch or brake pedal is depressed. |
| • | The engine is in Engine Coolant Over Temperature-Fuel Disabled mode. |
| • | The transmission is placed into neutral. |
| • | A concern with the clutch or brake pedal switches or circuits that the TAC module interprets as the pedal is applied. |
Diagnostic Aids
Important:
• Remove any debris from the PCM\TAC module connector surfaces before
servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets
when diagnosing/replacing the modules. Ensure that the gaskets are installed
correctly. The gaskets prevent contaminate intrusion into the PCM\TAC
modules. • For any test that requires probing the PCM or a component
harness connector, use the Connector Test Adapter Kit J 35616
. Using this kit prevents damage
to the harness/component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems.
| • | The following may cause an intermittent: |
| - | Inspect for poor connections; Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
| - | Corrosion |
| - | Mis-routed harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | 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 and DTC P0567 or DTC P0568 sets. |
| • | For an intermittent, refer to Symptoms . |
Scan Tool Display | Definition | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Brake Switches | The TAC module detects one of the brake switches active (TCC Brake Switch/Cruise Control Brake Switch or Stop Lamp Switch). | ||||||||||||||
Pedal Initialization | The PCM does not detect the brake or clutch switches active during an ignition cycle. | ||||||||||||||
Clutch Switch | The TAC module detects the clutch switch active. | ||||||||||||||
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. | ||||||||||||||
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. | ||||||||||||||
TAC Inhibit | The TAC module has detected that an Electronic Throttle Control fault is active. | ||||||||||||||
Accel (Acceleration) Rate | The vehicle acceleration is greater than the expected acceleration rate which is calculated by the PCM. | ||||||||||||||
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). | ||||||||||||||
CC (Cruise Control) Switch Position | The TAC module will not allow cruise with the current position of the cruise switches. | ||||||||||||||
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. | ||||||||||||||
Cruise Off | The TAC module does not detect that the cruise enable switch is active. | ||||||||||||||
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. | ||||||||||||||
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. | ||||||||||||||
PCM Inhibit | The PCM detects one of the following conditions:
| ||||||||||||||
Two CC Commands | The TAC module detects the Set/Coast and Resume/Accel switches are active at the same time. | ||||||||||||||
PCM Error | An internal PCM fault is detected. | ||||||||||||||
Traction Loss | The TAC module detects the vehicle is in a Traction Control event. | ||||||||||||||
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, P0502, P0503, P0567, P0568, P0571, P0601, P0602, P0604, P0606, P0704, P0719, P0724, P1258, P1574, or any Throttle Actuator Control system faults set? | -- | Go to Applicable DTC Table | |
3 | Inspect the Cruise Control fuse. Is the Cruise Control fuse open? | -- | ||
4 |
Does the scan tool display TCC/CC Brake Switch and the Stop Lamp Switch as Applied when the brake pedal was pressed? | -- | Go to DTC P0571 Cruise Control Brake Switch Circuit or DTC P0719 Brake Switch Circuit Low Input , DTC P0724 Brake Switch Circuit High Input (auto trans) or DTC P1574 Stoplamp Switch Circuit for stop lamp switch | |
5 |
Important: This step is for manual transmission vehicles only. If the vehicle has an automatic transmission, go to step 6. Using the scan tool on the Cruise Control data list, monitor the Clutch switch parameter while pushing the clutch pedal down. Does the scan tool display clutch switch as Depressed? | -- | ||
6 |
Does the scan tool display Cruise Switch ON? | -- | ||
7 |
Does the scan tool display Cruise Set/Coast ON when the switch was pushed in? | -- | ||
8 |
Does the scan tool display Cruise Resume/Accel as ON when the switch was pushed in? | -- | System OK | |
9 |
Does the test lamp illuminate? | -- | ||
10 | Probe the cruise ON/OFF signal circuit (TAC side of the circuit) using the test lamp J 35616-200 connected to B+. Does the test lamp illuminate? |
-- | ||
11 | Probe the cruise Set/Coast signal circuit (TAC side of the circuit) using the test lamp J 35616-200 connected to B+. Does the test lamp illuminate? | -- | ||
12 | Probe the cruise Resume/Accel signal circuit (TAC side of the circuit) using the test lamp J 35616-200 connected to B+. Does the test lamp illuminate? | -- | ||
13 |
Did the test lamp go OFF when the TAC module was disconnected? | -- | ||
14 | Test the Cruise Control Switch (lever side) circuits for a short to ground. Refer to Testing for Short to Ground in Wiring Repairs. Did you locate a short to ground on one of the Cruise Control lever circuits? | -- | Go to Diagnostic Aids | |
15 |
Does the test lamp illuminate? | -- | ||
16 |
Does the scan tool display Cruise Switch ON? | -- | ||
17 |
Is continuity indicated on the DMM? | -- | ||
18 | Repair the open Cruise ON/OFF signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
19 |
Does the scan tool display the Cruise Set/Coast parameter as ON when the voltage was applied? | -- | ||
20 |
Does the DMM indicate continuity? | -- | ||
21 | Repair the open Cruise Set/Coast signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
22 |
Does the scan tool display the Cruise Resume/Accel parameter as ON when the voltage was applied? | -- | ||
23 |
Does the DMM indicate continuity? | -- | ||
24 | Repair the open Cruise Resume/Accel signal circuit. Refer to Wiring Repairs in Wiring Repairs. Is the action complete? | -- | System OK | -- |
25 | Repair the open circuit between the Cruise Control Lever and the Instrument Panel Electrical Center. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
26 |
Is the action complete? | -- | System OK | -- |
27 |
Did you find and correct the condition? | -- | System OK | |
28 | Replace the Cruise Control Lever (multi-function lever). Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column. Is the action complete? | -- | System OK | -- |
29 |
Did you find and correct the condition? | -- | System OK | |
30 | Replace the TAC module. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement . Is the action complete? | -- | System OK | -- |
31 |
Is the action complete? | -- | System OK | -- |
