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        General >> Give/Need advice to/from others >> ABS.
        
(Message started by: Simmo on Aug 20^th, 2011, 7:36am)

Title: ABS.
Post by Simmo on Aug 20^th, 2011, 7:36am

My car recently developed a problem with the ABS light staying on. Changed the controller....no difference.....checked each of the sensors and found that the connector for the FOS was dodgy. Sorted that. Now the light comes and goesBUT sometimes, after starting and driving about 100 yards when I brake, quite normally and gently,for the first time the ABS 'kicks in'. Doesn't do it after that and the light is not affected??. Happened last night and then after about a mile I noticed the light had gone out only to reappear a short while later. The controller by the way is a Tompion re-solder so that should be OK and when he scanned it at the last Kent meet the fault was shown as the FOS sensor despite it giving a similar reading to the other three when checked with a meter. :-/ :-/ :-/ ???

Title: Re: ABS.
Post by Tompion on Aug 20^th, 2011, 11:53am

Mike,
When I had the ABS kicking in at low speed it was due to too big an air gap on a rear sensor – caused by the sensor wearing away when it touched the sensor ring (presumably due to wheel bearing failure). What that meant was the signal wasn’t strong enough at low speed so the ABS controller interpreted it as the wheel skidding.

The resistance test is only a guide it doesn’t show if the output is correct.

Check there’s no play in the wheel bearing & if you haven’t already done so remove the inner cap over the bearing nut and clean between the teeth of the sensor ring and around the sensor. It doesn’t need to be spotless, just get rid of loose/flaking rust.

I think a wiring problem is quite likely since there appeared to be a problem with or around the connector (based on what we tried at the Kent meet & what you did to fix it after) it may be an internal break in the wiring to the sensor plug so splicing in new wires & plug back to the controller may do the trick.

Of course it could be both controllers have failed.

Title: Re: ABS.
Post by Simmo on Aug 20^th, 2011, 12:21pm

Thanks Dave. It made a liar out of me today !. Went out.. light stayed on, first braking ABS cuts in. Another 150 yds, brake, ABS cuts in. OK after that, light goes out and stays off. Get home turn off ignition, turn on again and the light goes out as it should!!. When you talk about the cap over the bearing nut are you referring to the FOS wheel ? I have checked for bearing play but NOT removed/cleaned the sensor ring. Thanks for your advice,as ever. Both controllers have been 'Tompioned' so they're OK. ;) Mike. ;D

Title: Re: ABS.
Post by Tompion on Aug 20^th, 2011, 2:04pm

Yes the plastic cap over the bearing retaining nut - it's on the inside of the hub, the other end to the wheel. You'll have to crawl under :(

I did patch the repaired controller into my car & run it round the block tied up with string to check it passed the rolling test – but wouldn’t like to guarantee it :D

http://i.imgur.com/qJXCMCl.jpg

Title: Re: ABS.
Post by PJDavis on Aug 20^th, 2011, 6:20pm

I had a similar problem with mine fairly early on in ownership. I took the plastic cap out of the hub and there was a lot of grit and muck in and around the sensor-ring. Scraped each one with a small screw-driver, and pushed a rag in and turned the wheel, this solved the problem and no-problem since.

Title: Re: ABS.
Post by Simmo on Aug 20^th, 2011, 8:06pm

Thanks to both of you guys. I'll have a go next week. It's been spasmodic but a bit better today so may be cleaning will do the trick. Will let you know the outcome after I've done the 'Simmo Limbo' !! ::) ::)