Help !! Dither mode on Spending Money

[keithy1959]

I have a tatty 1999 V70 145k miles that I use with my Handyman Business. It has 11 month MOT, and is generally in good mechanical condition, apart from the ABS seems to kick in all the time whenever braking. There are no ABS warnings on the dash or error codes generated . When the car is driven in diagnostics mode, the fault goes away.

My mechanic ( not a Volvo specialist) suggests the ABS pump itself is faulty, and needs sending away to refurbish. He then will have to get the pump linked to the ECU which I understand is a job for a Volvo specialist. He is suggesting £500-600 poss more, and is not 100% confident that will fix it.

The car has 4 almost new tyres, new headlamps, and owes me nothing, so in the scheme of things, I'm happy to spend £600, as I'd have to pay at least £1000 to change it, but I don't want to throw good money after bad. If I went ahead, are there other gremlins that could then continue to run ?

Opinions and advice much appreciated
***Edit ***
Should say that price includes a loan car for however long it takes
I've used this mechanic on all our cars for the last 15 years, and I trust his advice.

[DaveNP]

Have you checked the condition of the ABS reluctor rings? I damaged one of mine recently which led to the ABS firing every time I braked, no fault indication as the ABS system read the missing tooth as a stopped wheel and pulsed the brake as it should if it was working properly. Replacing the ring cured the problem.

[BorderVolvo]

Pull the ABS fuse and keep driving?!

[Luxobarge]

Yes, classic symptoms of cracked or corroded ABS reluctor rings - probably the front ones, as the rears are inside the brake assembly and well protected.

Well worth spending out on to fix, not expensive and fairly easy. You could always try cleaning them up first, although this won't fix it if they're cracked.

[amazondean]

Definitely have both reluctor rings changed first, as the parts are only a few pounds and can be changed reasonably by a mechanic. I am surprised he hasn't suggested this first!

[keithy1959]

Originally Posted by BorderVolvo

Pull the ABS fuse and keep driving?!

TBH, thats exactly what I did for some time, but I'm guessing this would invalidate my insurance !!

[keithy1959]

Originally Posted by DaveNP

Have you checked the condition of the ABS reluctor rings? I damaged one of mine recently which led to the ABS firing every time I braked, no fault indication as the ABS system read the missing tooth as a stopped wheel and pulsed the brake as it should if it was working properly. Replacing the ring cured the problem.

Thanks, I'll take that up with my mechanic.
Out of interest, did you get any lights on the dash when the ABS was being applied. If the ABS kicks in on our other car, we get a flashing light on the dash but theres no indication on the V70.

[Luxobarge]

Originally Posted by keithy1959

Thanks, I'll take that up with my mechanic.
Out of interest, did you get any lights on the dash when the ABS was being applied. If the ABS kicks in on our other car, we get a flashing light on the dash but theres no indication on the V70.

With damaged reluctor rings, you usually don't get an ABS fault light. This is because as far as the ABS control unit is concerned, it's just getting a slower signal from one wheel, which is similar to what would happen if that wheel was skidding, therefore the ABS unit thinks that this wheel is indeed skidding and does what it's supposed to do, engages ABS braking, rather than recognise it as a fault.

[DaveNP]

As Luxobarge says, no lights because it acted like the wheel had stopped turning when it didn't get the pulse from the next tooth, normally the Abs doesn't often kick in when I'm driving and if it does I'll probably be paying more attention to the road than the dash but I don't recall it flashing a warning under proper circumstances. I was fortunate in that when I cleaned up the CV joint before doing the boot I noticed how crumbly the ABS ring was and almost expected the problem arising, true enough it showed up the first time I went down the street, quite a harsh pulsing on the offending wheel at speeds of around 20 mph but at any speed I could hear the ABS pump clicking away when I braked.

Changing the ring on the front is not too bad a job, basically release the CV joint shaft from the hub, undo the wishbone ball joint and swing the suspension strut out to release the CV joint from the hub, use a dremel or similar to cut the old ring off and clean the surface, heat the new ring (I put it on the gas ring until the coating started to change colour), run to car and slip it on before it cools and shrinks. I didn't quite get it straight before it cooled but a few taps with little hammer set it home, I had meant to make myself a copper drift tool before hand in case that happened but in the end managed without. Even as an amateur crawling on the garage drive it only took a couple of hours start to finish, most of that seemed to be trying to get the wishbone ball joint to release from the strut which I overcame by undoing the two other bolts and dropping the whole wishbone off.
The ring came from PFS/partsforvolvosonline.com/ about £11 plus postage, the flip side is that they also sell a whole CV joint, which has the ring already on it, for about £45 and it may be more cost effective for a paid mechanic to just change the whole joint rather than fiddle with the ring on the joint still on the car.