Component Specifications, Brake Control Module (BCM) [2015-2018]
COMPONENT SPECIFICATIONS
WHEEL SENSOR 7/31, 7/32, 7/56, 7/57
GENERAL
Type
Hall sensor (active sensor).
characteristic
When the toothed wheel rotates, a pulsed current signal (square wave) with fixed pulse ratio is generated. The frequency increases with speed.
Tooth at sensor
- I≈14 mA
Cover at sensor
- I ≈ 7 mA
Other information
Nothing
TERMINAL
Front wheel sensor
Rear wheel sensor
| Connector terminal | Control module terminal | Signal type | Miscellaneous |
|---|---|---|---|
| #1 | #45 | Power supply, front left | The sensor receives 12 V from the control module. |
| #14 | Signal output left front | Taxi signal. The signal can be used to check the wheel sensor's signal | |
| #2 | #46 | Signal ground | The sensor is grounded through the control module. |
| #1 | #36 | Power supply, rear left | The sensor receives 12 V from the control module. |
| #9 | Signal output left rear | Taxi signal. Can be used to check the wheel sensor's function | |
| #2 | #37 | Signal ground | The sensor is grounded through the control module. |
| #1 | #34 | Power supply, front right | The sensor receives 12 V from the control module. |
| #11 | Signal output right front | Taxi signal. Can be used to check the wheel sensor's function. | |
| #2 | #33 | Signal ground | The sensor is grounded through the control module. |
| #1 | #43 | Power supply, rear right | The sensor receives 12 V from the control module. |
| #7 | Signal output right rear | Taxi signal. Can be used to check the wheel sensor's function. | |
| #2 | #42 | Signal ground | The sensor is grounded through the control module. |
CHECK
Prerequisites (unless otherwise specified):
On special vehicles like police and taxi, all extra connected devices must be shut off as they may use any of the signal outputs in the table above.
- Breakout box connected.
- Sensor engaged.
- Ignition switch position II.
Create a temporary voltage feed between #1 on the breakout box via a resistor of 1kΩ and the sensor's signal output (#7, #9, #11, or 14). Connect a voltmeter between the sensor's signal output and ground connection #16. Turn the wheel slowly:
Tooth against sensor U ≈ ULow
Gap against sensor U ≈ Ubat
Direction sensitive wheel sensor
There is a direction sensitive wheel sensor on the front right. The signal is made up in a slightly different way, see Design and function, Brake control module (BCM), but the method for measuring and the appearance of the pulse train is the same.
PEDAL POSITION SENSOR 7/124
GENERAL
Type
Slide potentiometer.
The sensor is actuated by the brake pedal pushrod
characteristic
Resistance between terminals #2 and #3 should be approx. 0.5 kΩ when the brake pedal is not actuated. Resistance should increase when the brake pedal is depressed.
Resistance between terminals #3 and #1 should be approx. 2.5 kΩ when the brake pedal is not actuated. Resistance should decrease when the brake pedal is depressed.
Upon ignition, voltage should be:
0 mm ≈ 0.15 V (brake pedal not actuated)
38.5 mm ≈ 4.75 V (brake pedal depressed)
Other information
None.
TERMINAL
| Connector terminal | Control module terminal | Signal type | Ignition on | Miscellaneous |
|---|---|---|---|---|
| #1 | #26 | Power supply | U = 5 V | The sensor receives 5 V from the control module. |
| #2 | #27 | Signal ground | U = 0 V | |
| #3 | #38 | Signal voltage | U = 0.15 - 4.85 V |
CHECK
Prerequisites (unless otherwise specified)
- Breakout box connected
- Sensor connected
- Ignition switch position II
Check 1
Voltage between terminals #A3 and #A21 should be ≈0.15 V when the brake pedal is not actuated and up to ≈4.85 V when the brake pedal is depressed.
VACUUM SENSOR 7/160
GENERAL
Type
Vacuum pressure sensor: Double piezo resistive sensors
The sensor measures the pressure change between the vacuum chamber and the work chamber. The signal ratio between the chambers should correspond.
characteristic
Vacuum chamber (1): Voltage between terminals #30 (#A30) and #40 (#A40) should be similar to diagram 1 below.
Work chamber (2): Voltage between terminals 41 (A#41) and #40 (#A40) should be similar to diagram 2 below.
PEDAL PRESSURE SENSOR/CHECK VALVE (SAME CONNECTOR)
Type
Pedal pressure sensor: Two-pin, quickshifter located within the brake servo on the brake servo pushrod
Check valve: Electric coil with magnet core and valve
Characteristic pedal pressure sensor
Resistance between terminals #1 and #5 should be infinite when the brake pedal is not actuated and 0 Ω when the brake pedal is depressed
Resistance between terminals #2 and #5 should be 0 Ω when the brake pedal is not actuated and infinite when the brake pedal is depressed
Characteristic, check valve
Resistance between terminals #3 and #4 should be approx. 3 Ω.
Check, pedal pressure sensor
Prerequisites (unless otherwise specified):
Check
- Breakout box connected
- Sensor connected
- Ignition switch position II
Check 1, pedal pressure sensor
Voltage between terminals #21 (#A21) and #23 (#A23) should be 0 V when the brake pedal is not actuated and 12 V when the brake pedal is depressed.
Voltage between terminals #21 (#A21) and #24 (#A24) should be 12 V when the brake pedal is not actuated and 0 V when the brake pedal is depressed.
Check 1, check valve
Voltage between terminals #17 (A#17) and #31 (#A31) should be 12 V.