ABS/Central warning light on

[944cabby]

As it was a nice and clear but frosty this morning i decided to take the cab into town.Anyway took the car cover off and drove her out of my carport and started to drive off but just into the journey the central warning light and the ABS warning light came on.Braking appeared to be ok though and when i turned the ignition off and on the lights came on again within a few feet of driving.She's not done this before - is it likely to be a caliper sticking due to the frost?Any thoughts before i drop her in to a garage.

 

[Guest]

with the light coming on a few rolling feet after you start, I'd reckon it was one of the sensors gone/dirty. It appens a lot. The question now is, which one is it?

 

[kevinshally]

I've had the parking brake come on before when I was driving.
It happened on and off for a couple of days and then was no more.
I got it checked the next time I was getting the car checked over but there was no issue apparently.
I guess if the light is on then it's worth getting it checked out.
Kev.

 

[944cabby]

Thanks chaps, well i sprayed brake cleaner liberally all over the calipers and had a good look around - i couldn't see a loose sensor (i have noticed a slight leak from the hose connected to the base of the power steering reservoir though), so anyway took her for another spin when i dropped the "missus" off to work and everything seems to be fine again.Strange.

 

[Guest]

Hi,

Mine used to do that but it was acompanied with a noise from under the offside wing (where the ABS pump is) just before the light came on.
I replaced the pump (2 years ago) and it was OK for about 10 miles to and from the MOT station. Now (a month later) the light comes on after a few feet but without the noise.
Guess the pump was knackered as the noise has stopped and now, as it was sat so long, maybe the connectors are dirty too.
Is there anyway of testing the ABS system or is it dealer only?

 

[Guest]

I have a copy of the ABS test manual, and there is lots and lots of mentions of specialist tools. not nice at all. IIRC, there is some sort of troubleshooting guide on www.clarks-garage.com .

You should hear the pump after a few seconds on startup, that should show that things are OK. It sounds as though your pump is operating OK, ergo so the ECU *should* be fine too. It's more than likely a sensor problem again. If it's been sat for a while, whip the wheels off, and you can get to the sensors easily enough. unbolt them, pull them out and clean them (they are magnetic, so pick up all sorts of crud). while they are out, give the *insides* (aka the sensor wheel on the axle) a good blast of brake cleaner. The connectors *should* be OK as they are relatively well protected from rubbish, but you can clean them easily enough anyway.

 

[Diver944]

I didn't realise you could get to the sensors without taking the brake disks off [&:]

That's what I did a few years ago, when I had an intermittent ABS light. The sensor itself is a diamond shaped 'thing' behind teh brake disk and does get covered in all sorts of gunk.

There are also connectors for the front sensors under the bonnet just to the outside of the top of the shocks. Unbolt them and give tham a good going over with a wire brush.

You're not alone, our S2 ABS warning has recently started to intermittently come on again and I'd been putting off removing the brake disks to clean them [8|]

 

[944cabby]

Thanks for all the replies chap - she's had a good old run this afternoon as it's been dry.No more problems so far.Think i'll have a good nose at the calipers tomorrow and give them a good wash down.Never a dull moment with a '44 is there.Happy days!

 

[Guest]

ORIGINAL: rob_bot

Is there anyway of testing the ABS system or is it dealer only?

There's a very simple way to check your ABS. Drive along. hit the brake pedal hard and see if the wheels lock up.[]

However, if the ABS warning light has come on, it would mean that the ABS system has disabled itself, so you don't need to try this test. The theory is that it's better to revert to normal non ABS braking rather than try to cope with dodgy input data, and possibly end up releasing the brakes incorrectly.

If any of the main system warning lights come on (high water temp, low oil level, ABS etc.) you will also see the master caution light. It's just telling you that you really should stop as soon as it's safe and get the problem sorted out. Of all the warnings that cause the master caution light to come on, the ABS one is the only one that it's safe to continue to drive with, as long as you realise that you no longer have ABS.

James

 

[Fen]

ORIGINAL: JamesH
If any of the main system warning lights come on (high water temp, low oil level, ABS etc.) you will also see the master caution light. It's just telling you that you really should stop as soon as it's safe and get the problem sorted out. Of all the warnings that cause the master caution light to come on, the ABS one is the only one that it's safe to continue to drive with,

Except for handbrake or oil level caused by a failed sensor...

 

[Guest]

How would you know that the sensor had failed if the light came on? I'd still stop and check the oil before I continued my journey. That's really what the master caution light is telling you. You really should stop and find out exactly why the light is on.

 

[Fen]

I'd know the sensor had failed because I check my oil regularly using the dipstick so I know how much is in there. I guess there may have been a massive leak and I would tend to check the level manually if the light came on but experience suggests to me that the oil never gets low enough for the light to come on legitimately but the sender does fail quite often.

 

[Guest]

I once had a head gasket go quite catastrophically on a car. I was driving along and all the oil exited stage left. The oil warning light came on, and as I was stopping, a nasty knocking noise started from the bottom end.

As a result, if I ever get a warning light like that, even if I just checked the oil 5 minutes before, I stop and check again. A new head gasket is a lot cheaper than a new engine.

 

[Guest]

Dang right!

I've always found that the oil light like to come on after it's drunk 4 drops anyway. talk about over-zealous! But as you say, better safe than sorry.

 

[Fen]

I knoked a hole in the sump of my current 944. Neither the oil level light (which I believe only "reads" when the car is started) nor the oil pressure light came on at all, it was rattling top end that gave the game away. Both lights are worthless in my opinion.