Diagnosis System

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: DIAGNOSIS SYSTEM

1. DESCRIPTION

When troubleshooting a vehicle with a diagnosis system, the only difference from the usual troubleshooting procedure is connecting the Techstream to the vehicle and reading various data output from the vehicle's skid control ECU.

The skid control ECU records DTCs when it detects a malfunction in the ECU itself or in its circuits.

To check the DTCs, connect the Techstream to the DLC3 on the vehicle. The Techstream 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

(a) If the voltage is below 11 V, recharge the battery before proceeding to the next step.

2. DIAGNOSIS

(a) If the skid control ECU detects a malfunction, the ABS warning, brake warning, slip indicator and master caution indicator lights will come on in order to warn the driver.





(b) The 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 slip indicator lights, or by connecting the Techstream Vehicle Stability Control System.

(c) This system has a Test Mode (signal check) function.

The DTCs can be read by connecting SST between terminals TS and CG of the DLC3 and observing the blinking pattern of the ABS warning and slip indicator lights, or by connecting the Techstream Test Mode Procedure.

3. WARNING LIGHT AND INDICATOR LIGHT INITIAL CHECK

(a) Release the parking brake.

NOTICE:
When releasing the parking brake, move the shift lever to P for safety.

HINT
When the parking brake is applied or the brake fluid level is low, the brake warning light comes on.

(b) When the engine switch is turned on (IG), check that the ABS warning, brake warning, VSC OFF indicator and slip indicator lights will come on for approximately 3 seconds.





HINT
If the warning light and indicator light check result is not normal, proceed to troubleshooting for the ABS warning, brake warning, VSC OFF indicator and slip indicator light circuits.

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/she proceeds to troubleshooting without confirming the problem symptoms, he/she 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 engine switch is turned on (IG)).

(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.