Abs fault

[martin_r_smith]

Had the abs light coming in for a couple of weeks now, vol fcr shows a code for 'rear right wheel sensor fault in circuit'. Question is, is it more likely to be the sensor or the abs module itself? What's the best way to rule either out?

[cyteen]

The sensors are so cheap and the opening/reflow the module such a pain i'd check the continuity from the sensor to the plug, clean the contacts (both at the sensor and the abs module plug) and then buy a new sensor.

Fixing/replacing the abs module after that. If I'd done it that way I'd have saved a lot of time.

[stribo]

If you unplug the sensor and spin the wheel in question, the sensor should give voltage, if it's not, it's goosed.

[LeeT5]

If you unplug the sensor and spin the wheel in question, the sensor should give voltage, if it's not, it's goosed.

Really? How does that work then? If you unplug the sensor then it won't do anything because it will no longer be getting the 5v required.....or am I missing something?

Surely your mean't to back probe the sensor with it still connected?

Sorry, just realised what you mean. To clarify, you probe the sensor with it disconnected and check for alternating AC voltage.
I was thinking about an inductive sensor not Hall effect. :doh:

[martin_r_smith]

Are the rear sensors connected on the same loom? Ie come together as one when ordered?

[stribo]

I wouldn't have thought so, normally ABS sensors are individual.

[stribo]

Really? How does that work then? If you unplug the sensor then it won't do anything because it will no longer be getting the 5v required.....or am I missing something?

Surely your mean't to back probe the sensor with it still connected?

Sorry, just realised what you mean. To clarify, you probe the sensor with it disconnected and check for alternating AC voltage.
I was thinking about an inductive sensor not Hall effect. :doh:

Sorry, should have made it clearer, but yes, that's exactly what you do. :D

[martin_r_smith]

I wouldn't have thought so, normally ABS sensors are individual.

I thought that too but I ordered a rear wheel abs sensor and what arrived was both left and right going to one plug? Guess they've sent the wrong one.

[stribo]

Just checked ebay, and it looks like they are both on the same connector.
http://www.ebay.co.uk/itm/VOLVO-850-C70-S70-V70-REAR-LEFT-RIGHT-ABS-SPEED-SENSOR-9162612-/201189162079?fits=Car+Make%3AVolvo%7CModel%3A850&hash=item2ed7cefc5f:g:jXIAAOSwr81UNcOS

[JT]

You can unplug the abs unit and measure the resistance across the pins for each sensor.
I have tried this method 3 times and its taken me straight to the problem.

Only problem is, I can find the thread with the values on it :slap:

[JT]

cant find the thread, but did find my printed off instructions :B_thumb:

http://i1198.photobucket.com/albums/aa454/johnnytempest/IMG_3857_zpskeht38f2.jpg (http://s1198.photobucket.com/user/johnnytempest/media/IMG_3857_zpskeht38f2.jpg.html)