Depending on the type of malfunction detected by the electronic control unit, vehicle braking may be normal (without ABS influence) or with limited ABS action - controlled braking of the rear wheels only.
To check the circuits and components of the anti-lock system, connect a multimeter to the multi-pin connector of the anti-lock system electronic control device and take the appropriate measurements.
Checking the hydraulic circuit
Attention! Hydraulic circuit anti-lock system (ABS) Teves is under high pressure. Therefore, before starting all check operations, it is imperative to lower the pressure in it. To do this, turn off the ignition and strongly press the brake pedal about 20 times until it becomes "solid".
Checking the pressure in the pressure accumulator
1. Reduce the pressure in the pressure accumulator.
2. Remove pressure accumulator.
Connect test pressure gauge 12.009 with tee in place of pressure accumulator.
4. Connect the hydraulic accumulator to the tip of the tee.
5. Turn on the ignition.
6. Check whether the pressure rises quickly to a value of 4–9 MPa. If the pressure is different, the pressure accumulator must be replaced.
7. Unhook the cables from the loops.
8. Raise the car.
9. Clutch shield.
10. Lower bolts securing the clutch housing to the cylinder block.
Diagnosis of ABS system Teves
| Checked element | Measurement between contacts | Meaning | Measurement conditions |
| Weight of the housing of the electronic control unit of the ABS system | "1" and mass | 0 - 0.5 ohm | Ignition off |
| Weight of the hydraulic unit | "11" and mass | 0 - 0.5 ohm | Ignition off |
| Power supply voltage | "1" and "2" | More than 10 V | Ignition on |
| Main relay | "3" and "1" "8" and "1" "20" and "1" | 0 - 0.5 ohm 50 - 100 ohm 0 - 0.5 ohm | Ignition on |
| Main solenoid valve | "18" and "11" | 2 - 5 ohm | Ignition off |
| The electromagnetic inlet valve: – forward right; – front left; -rear | "15" and "11""35" and "11""17" and "11" | 5 - 7 ohms 5 - 7 ohms 5 - 7 ohms | Ignition off |
| Solenoid exhaust valve: -front right; – front left; -rear | "34" and "11" "16" and "11" "33" and "11" | 3 - 5 ohm 3 - 5 ohm 3 - 5 ohm | Ignition off |
| Brake fluid level sensor | "9" and "10" | 0 - 0.5 ohm | Ignition off |
| Front left wheel speed sensor | "5" and "23" | 0.8 - 1.4 ohm More than 0.5 V * | When measuring voltage, the ignition is off |
| Front right wheel speed sensor | "7" and "25" | 0.8 - 1.4 ohm More than 0.5 V * | When measuring voltage, the ignition is off |
| Rear left wheel speed sensor | "6" and "24" | 0.8 - 1.4 ohm More than 0.5 V * | When measuring voltage, the ignition is off |
| Rear right wheel speed sensor | "4" and "22" | 0.8 - 1.4 ohm More than 0.5 V * | When measuring voltage, the ignition is off |
| Sensor isolation | Sensor and ground | More than 20 kOhm | Ignition off |
| control light | "27" and weight | 0.5 - 1.5 V | Ignition on |
* Rotate the car wheel.
Attention! To prevent damage to the contacts of the multi-pin connector of the anti-lock braking system electronic control device, it is recommended to connect an adapter board, the contacts of which should be used to check electrical parameters in order not to use the contacts of the electronic control device connector during measurements.
Checking the charging time of the pressure accumulator
1. Reduce the pressure in the pressure accumulator.
2. Connect pressure gauge to pressure accumulator (see above).
3. Turn on the ignition.
4. Check the pressure stabilization time to 4–9 MPa. This time must be less than 60 seconds. If this condition is not met, then check the functioning of the pump, the condition of the filter in the brake fluid reservoir, the condition of the high pressure flexible pipes and the tightness of the tee connections.
Checking the tightness of the hydraulic unit
1. Reduce the pressure in the pressure accumulator.
2. Connect pressure gauge to pressure accumulator (see above).
3. Switch on the ignition and wait until the pressure stabilizes.
4. Switch off the ignition.
5. Wait 5 minutes and determine the pressure drop during this time. It should not exceed 1 MPa.
Checking the tightness of the hydraulic circuit
1. Reduce the pressure in the system.
2. Connect pressure gauge to pressure accumulator (see above).
3. Connect additional pressure gauges to the deaerators of both brake calipers of the front wheels.
4. Turn on the ignition.
5. Set the pressure to 10 MPa in the circuit by pressing the brake pedal using a special tool.
6. Determine the pressure drop on the pressure gauges after 5 minutes. It must not exceed:
- on calipers: 0.5 MPa;
- on pressure accumulator: 1.0 MPa.
7. If the pressure drop is greater, then check for leaks on the hydraulic pipe connections and, if necessary, replace the hydraulic control unit.
Checking the functioning of the pressure sensor of the electric motor of the hydraulic pump
1. Switch off the ignition.
2. Reduce the pressure in the hydraulic system.
3. Connect a pressure gauge to the pressure accumulator.
4. Turn on the ignition.
5. Wait until the hydraulic pump motor stops.
6. Check pressure after pump stop (maximum). This pressure should be 17.4–18.8 MPa.
7. Press the brake pedal.
8. Determine the pressure at which the electric motor of the hydraulic pump is turned on. This pressure should be 13–15 MPa. If this condition is not met, the hydraulic pump electric motor pressure sensor must be replaced.
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