Alex
Nordschleife
- Joined
- 6 Mar 2014
- Messages
- 22,176
This topic comes up quite regularly, especially now these cars are knocking on a bit so thought I'd do a little write-up that may help folk.
My ABS/PSM lights both came on last week so I had a go at fixing the problem myself. First thing I checked was the brake light switch. Easy enough to disconnect, twist and pull out of it's location. The switch easily comes apart and is really simple to check for continuity. There are 4 spades coming out the switch. Continuity is tested across each opposite pair. Put a voltmeter across both spades and actuate the button to ensure the circuit is closed then open. One pair was a bit ropy so I opened the switch up to see.
Once apart it was visible the contacts were caked in cr4p.
The spade connectors simply slide out and can be easily cleaned.
Cleaned up, all back together, continuity test passed and fit back in the car. Fault lights still illuminated so fault not cured. Next on to the wheel speed (ABS/PSM) sensors on each wheel.
Once the wheel is removed you can see on the hub assembly where the connectors are for the sensors and also the brake pad sensors. Simply pull the clip back that keeps them plugged in and then unplug the sensor. If you look into the sensor socket there are two sockets where the metal pins of the plug plug in to. Stick both prongs off your multimeter into the sockets and take a resistance reading.
I don't know whether the reading is ohms or k-ohms but each sensor was reading around 1.6. If you spin the disc when taking the reading, it should fluctuate up and down slightly. All sensors were giving the same reading apart from the rear left which wasn't outputting anything at all.
Fitted a new sensor today and took a reading. Reads slightly higher at 1.7 but put everything back together and lights have no gone off. Problem fixed
And only around £50 for a new sensor. Result!
My ABS/PSM lights both came on last week so I had a go at fixing the problem myself. First thing I checked was the brake light switch. Easy enough to disconnect, twist and pull out of it's location. The switch easily comes apart and is really simple to check for continuity. There are 4 spades coming out the switch. Continuity is tested across each opposite pair. Put a voltmeter across both spades and actuate the button to ensure the circuit is closed then open. One pair was a bit ropy so I opened the switch up to see.
Once apart it was visible the contacts were caked in cr4p.
The spade connectors simply slide out and can be easily cleaned.
Cleaned up, all back together, continuity test passed and fit back in the car. Fault lights still illuminated so fault not cured. Next on to the wheel speed (ABS/PSM) sensors on each wheel.
Once the wheel is removed you can see on the hub assembly where the connectors are for the sensors and also the brake pad sensors. Simply pull the clip back that keeps them plugged in and then unplug the sensor. If you look into the sensor socket there are two sockets where the metal pins of the plug plug in to. Stick both prongs off your multimeter into the sockets and take a resistance reading.
I don't know whether the reading is ohms or k-ohms but each sensor was reading around 1.6. If you spin the disc when taking the reading, it should fluctuate up and down slightly. All sensors were giving the same reading apart from the rear left which wasn't outputting anything at all.
Fitted a new sensor today and took a reading. Reads slightly higher at 1.7 but put everything back together and lights have no gone off. Problem fixed
And only around £50 for a new sensor. Result!