Diagnosis System
BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: DIAGNOSIS SYSTEM
DIAGNOSIS SYSTEM
1. DESCRIPTION
When troubleshooting a vehicle with the diagnosis system, the only difference from the usual troubleshooting procedure is connecting the intelligent tester to the vehicle and reading various data output from the vehicle's skid control ECU.
The skid control ECU records DTCs when the computer detects a malfunction in the computer itself or in its circuits.
To check the DTCs, connect the intelligent tester to the DLC3 on the vehicle. The intelligent tester enables you to erase the DTCs, activate the various actuators, and check the Freeze Frame Data and Data List.
(a) Check the battery voltage.
Standard voltage:
11 to 14 V
If the voltage is below 11 V, recharge the battery before proceeding to the next step.
(b) Check the DLC3.
The ECU uses ISO 15765-4 for communication. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.
If the result is not as specified, the DLC3 may have a malfunction. Repair or replace the harness and connector.
Verify the conditions listed in the table below.
NOTE: *: Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches or the doors.
HINT: Connect the cable of the intelligent tester to the DLC3, turn the ignition switch to the ON position and attempt to use the tester. If the display indicates that a communication error has occurred, there is a problem either with the vehicle or with the tester.
- If communication is normal when the tester is connected to another vehicle, inspect the DLC3 on the original vehicle.
- If communication is still not possible when the tester is connected to another vehicle, the problem may be in the tester itself. Consult the Service Department listed in the tester operator's manual.
2. DIAGNOSIS
(a) If the skid control ECU detects a malfunction, the ABS warning, brake warning, VSC OFF indicator, and SLIP indicator lights will come on in order to warn the driver.
The table below indicates which lights will come on when there is a malfunction in a particular function.
o: Light ON
-: Light ON (Blinking)
-: Light OFF
- DTCs are simultaneously stored in the memory. The DTCs can be read by connecting SST between terminals TC and CG of the DLC3 and observing the blinking pattern of the ABS warning and VSC OFF indicator lights, by connecting the intelligent tester Reading and Clearing Diagnostic Trouble Codes.
- This system has a sensor check function (test mode) Test Mode Procedure.
The DTC can be read by connecting the intelligent tester and observing the blinking pattern of the ABS warning and VSC OFF indicator lights.
3. WARNING LIGHT AND INDICATOR LIGHT INITIAL CHECK
(a) Release the parking brake.
NOTE: Before releasing the parking brake, move the shift lever to the P position for safety.
HINT: When the parking brake is applied or the level of the brake fluid is low, the brake warning light comes on.
(b) When the ignition switch is turned to the ON position, check that the ABS warning, brake warning, VSC OFF indicator, and SLIP indicator lights come on for approximately 3 seconds.
- If the skid control ECU has any stored DTCs, the ABS warning, brake warning, and SLIP indicator lights come on and the VSC OFF indicator light blinks.
- If the indicator does not come on or blink, check if the bulb is defective, and also check wire harness between the skid control ECU and the combination meter.
- If the indicator remains on or does not come on, proceed to troubleshooting for the light circuits listed below.
4. SYMPTOM SIMULATION
HINT: The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough customer problem analysis must be carried out. Then the same or similar conditions and environment in which the problem occurred in the customer's vehicle should be reproduced. No matter how experienced or skilled a technician may be, if he proceeds to troubleshoot without confirming the problem symptoms, he will likely overlook something important and make a wrong guess at some points in the repair operation. This leads to a standstill in troubleshooting.
(a) Vibration method: When vibration seems to be the major cause.
HINT: Perform the simulation method only during the primary check period (for approximately 6 seconds after the ignition switch is turned to the ON position).
(1) Slightly vibrate the part of the sensor considered to be the problem cause with your fingers and check whether the malfunction occurs.
(2) Slightly shake the connector vertically and horizontally.
HINT: Shaking the relays too strongly may result in open relays.
(3) Slightly shake the wire harness vertically and horizontally. The connector joint and fulcrum of the vibration are the major areas to be checked thoroughly.