Contents: Hydraulic circuit ↳ Checking the pressure in the… ↳ Checking the charging time of the… ↳ Checking the tightness of the… ↳ Checking the tightness of the… ↳ Checking the operation of the… ↳ Teves ABS System Diagnostics ↳
The electronic control unit also implements the auto-diagnostic function, warning the driver by lighting a control lamp about the occurrence of a malfunction of electrical circuits or elements of the anti-lock system. In addition, another control lamp informs the driver about a drop in pressure in the hydraulic system.
Depending on the type of fault detected by the electronic control unit, the vehicle's braking may be normal (without ABS action) or with limited ABS action - controlled braking of the rear wheels only.
To check the circuits and components of the anti-lock braking system, connect a multimeter to the multi-pin connector of the electronic control device of the anti-lock braking system and perform the appropriate measurements.
Hydraulic circuit
Warning! The hydraulic circuit of the Teves anti-lock braking system (ABS) is under high pressure. Therefore, before starting any testing operations, it is necessary to reduce the pressure in it. To do this, turn off the ignition and press the brake pedal hard about 20 times until it becomes "hard".
Checking the pressure in the pressure accumulator
1. Reduce the pressure in the pressure accumulator.
2. Remove the pressure accumulator.
3. Connect the control pressure gauge 12.009 together with the tee at the location of the pressure accumulator.
4. Connect the hydraulic accumulator to the tee tip.
5. Turn on the ignition.
6. Check whether the pressure quickly increases to 4–9 MPa.
7. If the pressure value is different, the pressure accumulator should be replaced.
Checking the charging time of the pressure accumulator
1. Reduce the pressure in the pressure accumulator.
2. Connect the pressure gauge to the pressure accumulator (see description above).
3. Turn on the ignition.
4. Check the time it takes for the pressure to stabilize to 4–9 MPa. This time should be less than 60 seconds.
5. If this condition is not met, then the operation of the pump, the condition of the filter in the brake fluid reservoir, the condition of the flexible high-pressure pipes and the tightness of the tee connections should be checked.
Checking the tightness of the hydraulic unit
1. Reduce the pressure in the pressure accumulator.
2. Connect the pressure gauge to the pressure accumulator (see description above).
3. Turn on the ignition and wait until the pressure stabilizes.
4. Turn 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 the pressure gauge to the pressure accumulator (see description above).
3. Connect additional pressure gauges to the deaerators of both front brake calipers.
4. Turn on the ignition.
5. Set the pressure to 10 MPa in the circuit by pressing the brake pedal using a special device.
6. Determine the pressure drop on the pressure gauges after 5 minutes. It should not exceed:
- on supports: 0.5 MPa;
- on the pressure accumulator: 1.0 MPa.
7. If the pressure drop is greater, you should check for leaks at the hydraulic pipe connections and, if necessary, replace the hydraulic control unit.
Checking the operation of the pressure sensor of the electric motor of the hydraulic pump
1. Turn off the ignition.
2. Reduce the pressure in the hydraulic system.
3. Connect the pressure gauge to the pressure accumulator.
4. Turn on the ignition.
5. Wait until the hydraulic pump engine turns off.
6. Check the pressure after stopping the pump (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 switched on. This pressure should be 13–15 MPa.
9. If this condition is not met, the hydraulic pump electric motor pressure sensor must be replaced.
Teves ABS System Diagnostics
The element being tested | Measuring between contacts | Meaning | Measurement conditions |
ABS electronic control unit housing weight | "1" and mass | 0 – 0.5 Ohm | Ignition is off |
Weight of hydraulic unit | "11" and mass | 0 – 0.5 Ohm | Ignition is off |
Power supply voltage | "1" and "2" | More than 10 V | Ignition is on |
Main relay | "3" and "1" | 0 – 0.5 Ohm | Ignition is on |
"8" and "1" | 50 – 100 Ohm | ||
"20" and "1" | 0 – 0.5 Ohm | ||
Main solenoid valve | "18" and "11" | 2 – 5 Ohm | Ignition is off |
Solenoid inlet valve: | |||
- front right | "15" and "11" | 5 – 7 Ohm | Ignition is off |
- front left | "35" and "11" | 5 – 7 Ohm | |
- rear | "17" and "11" | 5 – 7 Ohm | |
Solenoid release valve: | |||
- front right | "34" and "11" | 3 – 5 Ohm | Ignition is off |
- front left | "16" and "11" | 3 – 5 Ohm | |
- rear | "33" and "11" | 3 – 5 Ohm | |
Brake fluid level sensor | "9" and "10" | 0 – 0.5 Ohm | Ignition is 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 insulation | Sensor and mass | More than 20 kOhm | Ignition is off |
Control lamp | "27" and mass | 0.5 – 1.5 V | Ignition is on |
* Spin the wheel of the car.
Caution! To prevent damage to the contacts of the multi-pin connector of the electronic control unit of the anti-lock braking system, it is recommended to connect an adapter board, the contacts of which should be used to check the electrical parameters, so that the contacts of the electronic control unit connector are not used during the measurement process.
(The material was copied from an information website: «www.FordBook.ru»)