Some deviations in the operation of the ABS system
On models equipped with ABS, deviations may occur from time to time that are not signs of a malfunction.
1. The sound of the system health check.
After starting the engine, sometimes a dull sound can be heard from the engine compartment. This is a sign that the control procedures for checking the performance of the ABS system are being carried out.
2. Sounds of the ABS system.
- A) The sound of the pump motor running inside the ABS hydraulic unit (howling sound).
- b) Sound accompanied by brake pedal vibration (scraping).
- V) Sounds in the chassis of the car as a result of the periodic pressing and releasing the brake pedal.
Note: Undercarriage thuds usually come from the suspension and squeaks from the tires.
3. ABS system operation (long stopping distance).
On gravel and snowy roads, the stopping distance of a vehicle with ABS may sometimes exceed that of a vehicle with standard brakes. Therefore, it is recommended that drivers not be overconfident and, for safety reasons, slow down when driving on such roads.
4. Feeling of vibration on the brake pedal.
Vibration in the brake pedal is due to the activation of the ABS solenoid valves and is a sign of normal ABS system operation.
Checking the indicator "ABS"
1. Turn the ignition key to position "ON" and make sure the indicator "ABS" lit up for two seconds and went out.
2. Make sure the indicator is off while the vehicle is moving. If the indicator is on, this indicates a malfunction.
Reading trouble codes with a tester
1. Set the key in the ignition switch to position "OFF".
2. Connect the tester to the diagnostic socket as shown in the figure.
3. Turn the ignition key to position "ON".
4. Using a tester, read diagnostic trouble codes.
5. Determine the malfunction by reading the code and make the necessary repairs or troubleshooting (see table "Fault codes for ABS/EBD/TCS systems").
6. After completing the repair or correcting the malfunction, turn the key in the ignition switch to the position "OFF".
7. Delete trouble codes from the memory of the electronic control unit using the reset button of the tester.
8. Disconnect the tester.
Table. Fault codes for ABS/EBD/TCS systems.
Check of components of systems ABS/EBD/TCS
This operation involves checking the signals of the components at the terminals of the connector of the electronic control unit for ABS / EBD / TCS systems (see table "Signals at the terminals of the connector of the electronic control unit for ABS / EBD / TCS systems").
Note: when performing the test, be careful to use sufficiently thin gauge probes to avoid damage to the connector pins.
Electronic control unit connector (models up to 2001).
Electronic control unit connector (models since 2001).
Checking with functions "CURRENT DATA" And "ACTUATOR DRIVING" tester
General verification procedures
1. With the ignition off, connect the tester to the diagnostic socket.
2. Check using the functions "CURRENT DATA" And "ACTUATOR DRIVING" tester. In the event of a malfunction, check the vehicle's electrical wiring, relevant components and parts.
3. After the repair, recheck with a tester and make sure that the incorrect input and output signal has returned to normal as a result of the repair (correspond to the norm).
4. Erase the diagnostic trouble codes from the memory of the electronic engine control unit.
5. Start the engine and carry out a road test to ensure that the problem has been corrected.
Checking actuators with a tester
1. Set the key in the ignition switch to position "ON".
2. To force the actuator to turn on, use the function "ACTUATOR DRIVING" tester.
Note: forced activation of the actuator takes 20 seconds.
Attention:
- Actuators cannot be checked if the emergency mode of the ABS system is activated.
- Carry out the check, making sure that the wheels of the car are stationary.
3. Check for an ABS valve click for each channel of the hydraulic block (FR-IN, FL-IN, RR-IN, RL-IN, FR-OUT, FL-OUT, RR-OUT, RL-OUT) when the valve is activated.
4. Verify that the pump motor relay clicks when the motor is activated.
Checking system components with a tester
1. Set the key in the ignition switch to position "ON".
2. To check the system components, use the function "CURRENT DATA" tester.
3. Check system components (see table "Checking components using a function "CURRENT DATA").
Table. Checking components using a function "CURRENT DATA".
Component symbol | Diagnostic object |
FL wheel speed SNSR | Front left wheel speed sensor (km/h) |
FR wheel speed SNSR | Front right wheel speed sensor (km/h) |
RL wheel speed SNSR | Rear left wheel speed sensor (km/h) |
RR wheel speed SNSR | Rear right wheel speed sensor (km/h) |
ABS SRI status | ABS indicator status |
Brake SW | Stoplight switch |
Motor pump relay | Pump Motor Relay |
Valve relay | Solenoid valve relay |
Motor pump status | Pump motor status |
FL valve (In) | Front Left Wheel Brake Line Inlet Solenoid Valve |
FR valve (In) | Front Right Wheel Brake Line Inlet Solenoid Valve |
RL valve (In) | Rear Left Wheel Brake Line Inlet Solenoid Valve |
RR valve (In) | Rear Right Wheel Brake Line Inlet Solenoid Valve |
FL valve (Out) | Front left wheel brake line output solenoid valve |
FR valve (Out) | Front Right Wheel Brake Line Output Solenoid Valve |
RL valve (Out) | Rear Left Wheel Brake Line Output Solenoid Valve |
RR valve (Out) | Rear Right Wheel Brake Line Output Solenoid Valve |
Table. Signals at the terminals of the connector of the electronic control unit for ABS / EBD / TCS systems (models up to 2001).
Conclusion | Signal | Designation |
1 | Supply of solenoid valves | VLV PWR |
2 | Weight | GND |
3 | K-Line diagnostic circuit | K-Line |
4 | Left rear wheel speed sensor | RL |
5 | Left rear wheel speed sensor | RL |
6 | Nutrition | IG2 |
7 | - | - |
8 | Left front wheel speed sensor | FL |
9 | Left front wheel speed sensor | FL |
10 | Indicator "ABS" | ABS IND |
11 | - | - |
12 | Indicator "TCS" | TCS IND |
13 | TCS switch | TCS SW |
14 | - | - |
15 | CAN data bus (signal "Low") | CAN - Low |
16 | CAN data bus (signal "High") | CAN - High |
17 | ABS pump motor power supply | ABS MTR PWR |
18 | Weight | GND2 |
19 | Right rear wheel speed sensor | RR |
20 | Right rear wheel speed sensor | RR |
21 | - | - |
22 | Right front wheel speed sensor | FL |
23 | Right front wheel speed sensor | FL |
24 | Stoplight switch | STP |
25 | Indicator "TCS-OFF" | TCS-OFF IND |
Table. Signals at the terminals of the connector of the electronic control unit for ABS / EBD / TCS systems (models since 2001).
Conclusion | Signal | Designation |
1 | Left front wheel speed sensor | FL |
2 | Left front wheel speed sensor | FL |
3 | - | - |
4 | Nutrition | IG2 |
5 | Left rear wheel speed sensor | RL |
6 | Left rear wheel speed sensor | RL |
7 | K-Line diagnostic circuit | K-Line |
8 | Weight | GND |
9 | Supply of solenoid valves | VLV PWR |
10 | CAN data bus (signal "Low") | CAN - Low |
11 | CAN data bus (signal "High") | CAN - High |
12 | - | - |
13 | TCS switch | TCS SW |
14 | Indicator "TCS" | TCS IND |
15 | - | - |
16 | Indicator "ABS" | ABS IND |
17 | Indicator "TCS-OFF" | TCS-OFF IND |
18 | Stoplight switch | STP |
19 | Right front wheel speed sensor | FL |
20 | Right front wheel speed sensor | FR |
21 | - | - |
22 | Right rear wheel speed sensor | RR |
23 | Right rear wheel speed sensor | RR |
24 | Weight | GND2 |
25 | ABS pump motor power supply | ABS MTR PWR |