ABS-142
C. ABS-142 Brake light switchCA. DTC information
Condition
DTC ABS-142 will be posted if the car's road speed is over 40 km/h (24 mph) and falls below 3 km/h (2 mph) during two consecutive brakings without the control module registering any signal change from the brake light switch.
Substitute value
None
Possible source
- Signal cable short circuited to ground or current.
- Signal cable break
- Defective brake light switch
- Contact resistance in the connections
- The car's road speed has been reduced without using the brake pedal, e.g. application of the parking brake.
Fault symptom(s)
Any ABS control will be characterized by a somewhat rougher control in the beginning.
Fault-tracing begins with [CB].Other DTCs, status notifications and status checks
CB. Other DTCs, status notifications and status checks
[CB1]
Other DTCs
Select one of the above alternatives to continue.
Alternative 1:CB2
Alternative 2: CB3
[CB2]
Status notification
- Read out other DTCs
Select one of the following alternatives to continue.
Alternative 1: Fault-tracing as per CC. Incorrect signal. Permanent fault.
Alternative 2: Fault-tracing as per CD. Incorrect signal. Intermittent fault.
[CB3]
Status check
- Ignition on.
- Go into rolling value, list 3.
Note the brake light switch reading.
With the brake pedal released the reading should indicate OFF.
With the brake pedal depressed the reading should indicate ON.
If reading is OK: Fault-tracing as per CD. Incorrect signal. Intermittent fault
If reading is incorrect: Fault-tracing as per CC.Incorrect signal. Permanent fault
CC. Incorrect signal. Permanent fault
[CC1]
Check brake light status
- Ignition on.
- Go into rolling value list 3.
Note the brake light switch reading.
With the brake pedal released the reading should indicate OFF
With the brake pedal depressed it should indicate ON.
Is ON indicated all the time?
Yes: CC2
No: CC7
[CC2]
Check the brake light switch
- Remove the sound insulation.
- Ignition on.
- Go into rolling value list 3.
Disconnect the brake light switch and note the brake light switch reading.
Is the reading altered to OFF?
Yes: CC4
No: CC3
[CC3]
Check for short circuiting
Check the cable between control unit #12 and the brake light switch contact connection 2 and the brake light cable for short circuiting to power as per [IIIB4]. Check Communication to Control Module [III]
For automatic vehicles: Check the cable between brake light switch contact connection 2 and automatic gearbox control module #B26 for short circuiting as per [IIIB4]. Check Communication to Control Module [III]
Then continue with: CC18
[CC4]
Check of the brake light switch adjustment
Hint: The brake light switch is automatically adjusted.
- Remove and set the brake switch as per [WWWA]. Brake light switch (later model) for a new base setting
- Reconnect the brake light switch.
- Release the brake pedal.
- Ignition on.
- Go into rolling value list 3.
Note the brake light switch reading.
With the brake pedal released the reading should indicate OFF.
If reading is OK: CC5
If reading is incorrect: CC6
[CC5]
Fault cause
The fault has been caused by incorrect adjustment of the brake light switch
Then continue with: CC18
[CC6]
Replacing a component
Test with a new brake light switch as per Brake light switch.
Then continue with: CC18
[CC7]
Check the brake lights
- Depress the brake pedal.
Are the brake lights lit when the brake pedal is depressed?
Yes: CC8
No: CC9
[CC8]
Check for cable breaks
Check the cable between the brake light switch contact connection 2 and control module #12 for breaks as per [IIIB2]. Check Communication to Control Module [III]
Then continue with: CC18
[CC9]
Check fuse 11/12
Check that fuse 11/12 is intact.
Is fuse 11/12 intact?
Yes: CC11
No: CC10
[CC10]
Check for short circuiting and replace component
Check the cable between control module #12 and fuse 11/12 and the cable to the brake light for short circuiting to ground as per [IIIB3]. Check Communication to Control Module [III]
For automatic vehicles: Check the cable between the brake light switch contact connection 2 and the automatic gearbox control unit #B26 for short circuiting to ground as per [IIIB3]. Check Communication to Control Module [III]
Then replace the fuse.
Then continue with: CC18
[CC11]
Check the voltage in fuse 11/12
- Ignition off
Connect a voltmeter between the rear terminal on the fuse holder (against the window) for fuse 11/12 and ground.
The voltmeter should indicate the battery voltage.
If reading is OK: C13
If reading Is incorrect: CC12
[CC12]
Check for cable breaks
Check the cable between fuse 11/12 and the battery for breaks as per [IIIB2]. Check Communication to Control Module [III]
Then continue with: CC18
[CC13]
Check the voltage to the brake light switch
- Ignition on.
- Remove the sound insulation.
Connect a voltmeter between brake light switch connection 1 and ground.
The voltmeter should indicate the approximate battery voltage.
If reading is OK: CC15
If reading Is Incorrect: CC14
[CC14]
Check for cable breaks
Check the cable between the brake light switch connection 1 and fuse 11/12 for cable breaks as per [IIIB2]. Check Communication to Control Module [III]
Then continue with: CC18
[CC15]
Check the brake light switch
- Ignition off.
Connect a voltmeter between brake light switch connection 2 and ground.
- Depress the brake pedal.
The voltmeter should indicate the approx. battery voltage
If reading is OK: CC16
If reading is incorrect: CC17
[CC16]
Check for cable breaks
Check the cable between brake light switch contact connection 2 and control module #12 for breaks as per [IIIB2]. Check Communication to Control Module [III]
Then continue with: CC18
[CC17]
Replace a component
Test with a new brake light switch as per [WWWA]. Brake light switch (later model).
Then continue with: CC18
[CC18]
Verification
Hint: After repair it is necessary to check that the fault has been rectified
- Ignition on
- Go into rolling value, list 3
Note the brake light switch reading
With the brake pedal released the reading should indicate OFF
With the brake pedal depressed the reading should indicate ON
If reading is OK: Fault corrected
If reading is incorrect: CC19
[CC19]
Fault-tracing information
The verification result shows that the fault persists.
Do you want to exit fault-tracing?
Yes: Fault not corrected
No: CC1
CD. Incorrect signal. Intermittent fault
[CD1]
Check cables and connections
Check the brake light switch and control module contacts for contact resistance and oxidation as per [IIIB6]. Check Communication to Control Module [III]
Check the cable between brake light switch contact connection 1 and the battery for intermittent breaks as per [IIIB2]. Check Communication to Control Module [III]
Check the cable between brake light switch contact connection 2 and control module #12 for intermittent breaks as per [IIIB2] intermittent short circuiting to earth as per [IIIB3] and intermittent short circuiting to current as per [IIIB4]. Check Communication to Control Module [III]
For automatic vehicles: check the cable between brake light switch contact connection 2 and the automatic gearbox control module for intermittent short circuiting to earth as per [IIIB3] and intermittent short circuiting to current as per [IIIB4]. Check Communication to Control Module [III]
Then continue with: CD2
[CD2]
Fault-tracing information
For intermittent faults fault-tracing is not followed by a verification because the fault is not present at this moment.
Do you want to repeat fault-tracing?
Yes: CD1
No: Operation done