Cruise Control System - Diagnostics: Pre-Check

DIAGNOSIS SYSTEM

Description
ECM controls the function of the cruise control on a vehicle.

Data on the cruise control and on the DTC can be read from the DLC3 on the vehicle. If CRUISE MAIN indicator does not comes on after the DTC check, there is a malfunction on the cruise control.

Use the LEXUS hand-held tester or SST to check and solve the problem.

Fig 1: Connecting Hand-Held Tester To DLC3
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the DLC3.

The vehicle's ECM uses ISO 9141-2 for communication.

The terminal arrangement of DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

Fig 2: Checking DLC3

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DLC3

Terminal No.	Connection/Specified Condition	Condition
4	Chassis Ground (Ω) Body Ground / 1 <->or less	Always
7	Bus+ Line / Pulse Generation	During Communication
16	Battery Positive <->Body Ground / 9-14 V	Always

HINT:

If the display shows "UNABLE TO CONNECT TO VEHICLE" as connecting the LEXUS hand-held tester to the DLC3 and turn the ignition ON, there is a problem either on the vehicle or on the tool.

If communication is normal when connecting the tool to another vehicle, inspect DLC3 on the original vehicle.
If communication is still not possible when connecting the tool to another vehicle, the problem is probably in the tool itself. Consult the Service Department listed in the tool's instruction manual in that case.

Check the indicator.
1. Turn the ignition switch to ON.
2. Check that the CRUISE MAIN indicator light comes on when the cruise control main switch is turned ON, and that the indicator light goes off when the main switch is turned OFF.
HINT:

If the indicator check result is not normal, proceed to troubleshooting (See PROBLEM SYMPTOMS TABLE ) for the combination meter .

Fig 3: Identifying CRUISE MAIN Indicator Light
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Check the DTC.
HINT:

If a malfunction occurs in the speed sensor or in the stop light switch, etc. during cruise control driving, the ECU actuates AUTO CANCEL of the cruise control and turns ON and OFF the CRUISE MAIN indicator light to inform the driver of a malfunction. At the same time, the malfunction is stored in memory as a diagnostic trouble code.

Fig 4: Identifying Indicator Light Blinking Pattern
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Output DTC using diagnosis check wire.
1. Turn the ignition switch ON.
2. Using SST, connect terminals TC and CG of DLC3.
  1. SST 09843-18040
  Fig 5: Connecting Terminals TC And CG
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Read the DTC on the CRUISE MAIN indicator light.

HINT:

If the DTC is not output, inspect the diagnosis circuit.

As an example, the blinking patterns for codes; normal 52 are shown in Fig 6 .

Fig 6: Example Blinking Patterns For Normal 52 Codes

USING LEXUS HAND-HELD TESTER
1. Hook up the LEXUS hand-held tester to the DLC3.
2. Monitor the ECU data by following the prompts on the tester screen.
HINT:

LEXUS hand-held tester has a "Snapshot" function which records the monitored data.

Please refer to the LEXUS hand-held tester operator's manual for further details.

Fig 7: Connecting Hand-Held Tester To DLC3
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DATA LIST
HINT:

According to the DATA LIST displayed by the hand-held tester, you can read the value of the switch, the sensor and so on without parts removal. Reading the DATA LIST as a first step of troubleshooting is one of the method to shorten the labor time.
1. Connect the Hand-held tester to the DLC3.
2. Turn the ignition switch ON.
3. According to the display on tester, read the "DATA LIST".
Fig 8: Data List
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

"3" is OK but "1" is NG ->ECM failure

"1" is OK but "2" is NG ->DTC output or ECM failure

"3" is OK but cruise indicator not turn on ->Indicator or W/H or ECM failure
DTC CLEARANCE
1. The following actions will erase the DTCs and freeze frame data.
  1. LEXUS Hand-Held Tester:
    Operating the LEXUS hand-held tester to erase the codes.
  2. Except LEXUS Hand-Held Tester:
    Disconnecting the battery terminals or EFI fuse.
2. After completing repairs, the DTC retained in memory can be cleared by removing the EFI fuse for 1 minutes or more with the ignition switch off.
3. Check that the normal code is displayed after connecting the fuse.
PROBLEM SYMPTOM CONFIRMATION (ROAD TEST)
1. Inspect the SET switch.
  1. Push the main switch button to ON.
  2. Drive at a desired speed (40 km/h (25 mph) or higher).
  3. Push down the control switch to the SET/COAST.
  4. After releasing the switch, check that the vehicle cruises at the desired speed.
  Fig 9: Inspecting SET Switch
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Inspect the ACCEL switch.
  1. Push the main switch button to ON.
  2. Drive at a desired speed (40 km/h (25 mph) or higher).
  3. Check that the vehicle speed increases while the control switch is pull up to RES/ACC, and that the vehicle cruises at the set speed when the switch is released.
  4. Momentarily press the control switch upward to the RES/ACC and then immediately release it. Check that the vehicle speed increases by about 1.5 km/h (Tap-up function).
  Fig 10: Inspecting ACCEL Switch
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Inspect the COAST switch.
  1. Push the main switch button to ON.
  2. Drive at a desired speed (40 km/h (25 mph) or higher).
  3. Check that the vehicle speed decreases while the control switch is push down to SET/COAST, and the vehicle cruises at the set speed when the switch is released.
  4. Momentarily press the control switch downward to SET/COAST, and then immediately release it.
    Check that the vehicle speed decreases by about 1.5 km/h (Tap-down function).
  Fig 11: Inspecting COAST Switch
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Inspect the CANCEL switch.
  1. Push the main switch button to ON.
  2. Drive at a desired speed (40 km/h (25 mph) or higher).
  3. When operating one of the followings, check that the cruise control system is cancelled and that the normal driving mode is reset.
    - Depress the brake pedal
    - Depress the clutch pedal (M/T)
    - Shift to except D range (A/T)
    - Push the main switch OFF
    - Pull the cruise control switch to CANCEL
  Fig 12: Inspecting CANCEL Switch
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
5. Inspect the RESUME switch.
  1. Push the main switch button to ON.
  2. Drive at a desired speed (40 km/h (25 mph) or higher).
  3. When operating one of the followings, check that the cruise control system is cancelled and that the normal driving mode is reset.
    - Depress the brake pedal
    - Depress the clutch pedal (M/T)
    - Shift to except D range (A/T)
    - Pull the cruise control switch to CANCEL
    Fig 13: Inspecting RESUME Switch
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. After the control switch is turned to RES/ACC at the driving speed of more than 40 km/h (25 mph), check that the vehicle restores the speed prior to the cancellation.
INPUT SIGNAL CHECK (Using LEXUS hand-held tester)
1. Connect the LEXUS hand-held tester to DLC3
2. Check the control switch (MAIN, CANCEL, SET/COAST, RES/ACC)
  
  Fig 14: Checking Input Signal (Using LEXUS Hand-Held Tester)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002