Testing ABS Sensors

[MountainGoat]

I mentioned at the beginning of the week in the Scottish Section that I was having a problem with my ABS light staying on after hitting a bad patch of potholes on my way back from the day meet at Aberfoyle last Sunday.

Had a word with Ady about it who claimed not to be an expert on the subject but suggested that one sensor may have packed up or just needs cleaning (the rear nearside one is my suspect).

Downloaded all the information from Bongo Fury that I could find and this article from the web http://www.topbuzz.co.uk/maintenance/te ... ng_abs.htm But it is all Dutch to me. My Bongo is a 4x4 with Normal Diff so with only one wheel jacked up and removed turning the wheel as suggested in the web article is not possible, it just won't turn.

Ady believes that replacement is a simple pull out and push in job. But first I need an expert to tell me just where the contol box under passenger footwell is actually located and how to test it (the only box that can find is behind a couple of wiring looms) and how to test the sensors at the wheel.

All advice gratefully received before I spash out £172.00 for a new sensor or start hunting for a useable second hand one.

Tony

[TonyBee]

Have you physically looked at each sensor?
It may be as simple as one has become dislodged when you hit the potholes.
They have to be close enough to the segmented rotor on each shaft to be able to detect motion or lack of it and one may have moved away far enough to have lost detection.
The sensor internals are just wire coils and are fairly robust. My money would be on one coming loose from its mounting.

Tony

[Rhinoman]

You should check that the sensor is clean with no metal debris stuck to it. The gap between the sensor and the toothed wheel must also be correct.
That article may not be correct, it describes a hall effect sensor, I think that ours are Variable Reluctance (VR) sensors.

[321Away]

to test the sensors, unplug each and using a multimeter set to read resistance (ohms), each sensor should read about 1600, typically the 1640 range, any that dont are dead, best place to start is to check the fuse in the fusebox under the bonnet as if this slips, it brings the light on as soon as the car starts rolling. The rear sensors are located under the vehicle just in front of the rear wheels fixed to the inside of the sill members and are bit of a pain to get at if the car is on the floor, and the fronts are located under the bonnet, the offside is clipped under the main battery and the nearside can be found just behind the nearside headlight, all have 2 wires, 1 black,1white.
Julian

[Jaws]

Probably unrelated but I had a problem with the ABS light when I tried swapping the brake light bulbs for LED replacements. It seems the ABS will only work when it senses you have working brake lights of a certain resistance. Filaments have been known to break when jolted as on a potholed road...

I'm sure you have checked this but just thought it worth a mention in case.

[AlliDelta]

I can probably sort you out the replacement sensors if you need em off the Bongo I'm breaking. If you find you need em

[MountainGoat]

Sent you a PM.

Tony