abs light...

Yes, you can check the alternator output with a voltmeter... best is 14.4V with RPM about 1500RPM and the least is 13.5V at idle. Otherwise, your alternator is weak and should be replaced. The fact that your battery charge light lites up means something is already wrong with it. You can try just changing the brushes... very easy job... two scres on back of alternator. However, it is a temporary fix... you probably gets 3 years out of it before problem comes back again.

Yes, change that brake switch... it is cheap enough to replace without testing. Testing means nothing on brake switch.

As for bulb, you really need German bulbs to eliminate this problem... or that you simply missed one bulb.

Check the fuse on the overvoltage protection relay. Or it may be the relay itself. It resides behind the battery. The OVP makes all sorts of weird things happen when it goes bad, the ABS light is one of them.

ok cheers for that mate i'll go round again tomorrow and recheck everything - which brand bulbs are actually German? also, just found some stuff says that the steering needs recentring after a flat battery, how would I do that? cheers again

cheers mate, um, how do I find/recognise the relay, and is there any way to test it? - just nipped and looked, is that a removable cover behind the battery? cheers for the assists!

Remove that cover. There should be 2 relays behind it, maybe only one if you haven't A/C. The OVP relay has a fuse on top under a clear plastic cover. Check the fuse and check for voltage at the fuse with the engine running. No voltage means the relay is bad.

Yes, I forgot about the OVP... located behind battery... behind the plastic cover.

okay, cheers for the help so far but nothing doing yet

-Voltmeter showed about 13.5V at tickover no load and about 13V with lots of things on so I guess that's ok...

- fitted new brake switch, no change

-tested the OVP relay and fuse and that's all working as well... anything else I can try? just had a thought re the bulb failure light, as it only comes on with the ignition is there a relay controlling that? all the best!

How did you check for load? What is no load voltage at 1500 RPM?

----- Original Message ----- From: "Tiger" Newsgroups: alt.auto.Mercedes Sent: Friday, December 15, 2006 12:25 AM Subject: Re: abs light...

hi sorry for the delay been off on a course I just tested the Voltage at tickover with the headlights, flashers, radio wipers and a few other bits on just to see if it held up, I think it was a fraction over 13V at tickover I'm pretty sure the alternator is fine because I just drove a hundred miles with lights on without a hitch and it started fine after being left out in the rain all night! The ABS light now usually comes on the first time I change into neutral or drive after pulling off (pedal kicks a bit, and a second or two of pump noise (?) I think it actually stops working after this, now I did notice quite a bad leak through the windscreen which seems to be going behind the dash board.... guess that needs checking out :(

cheers ! plus sorry I may have misdirected this initially - cockpit thrombosis....

well that's another one for my big mouth...car started ok this morning despite freezing fog, drove a couple of miles, came to restart..... nothing.Flat as a pancake. So how do I properly check out the alternator? cheers all

Any Autozone will test the battery and charging system for you... just drive it there. Free...

Other places might charge you... but most auto parts store can test alternator for free.

well I bit the bullet and put it in to a shop this morning, see if the professionals can come up with something, I expect some (probably expensive) news this afternoon....

FYI

well the man says he found 0.12A drain via 'courtesy light circuit' - is that the internal lights that come on when you open the doors? replaced ABS relay, I'm not sure which one this is but hey -ho also some problem with the resistance of one front ABS sensor, but he reckons they run out at about £90 each new, and says it may need the pair replacing to keep the readings equal eeek, however might be able to source second-hand pair at something more reasonable if I give him a few weeks notice

Anyway, I think I read somewhere you need to 're-centre' the steering after battery out, anyone know the drill? just turn lock to lock a few times or is there more to it? cheers

hmmm just noticed , while testing to see if the ABS actually functions even when warning light is on - under 'quite' heavy braking the battery charge light is coming on dimly, wonder if the brake lights are faulty somehow, must check the earths and stuff - its 5-door so maybe lost a line or something in the door.... cheers!

Sounds like your battery is suspect, I suggest you have it tested.

I do not know about a 1998, but on my 1999 ABS light can be reset by

hi mate well the battery already got done last week, but good thought about the manual, I forgot its actually quite useful, though I cant actually find anything about it in there but cheers for the tip (mines actually '88 but I'll try any way) cheers!

"news@mung" wrote:

Well, a 120mA drain on the battery is still not going to flatten a good battery, unless you have left the car a couple of weeks. I think that you are onto something with the charging light glowing. It shouldn't do that. As I also recall, the alternator voltage regulator is set to 13.8Volts and not higher. As suggested by others, change this part. Its cheap and easy. Also, you need to check the circuitry around the dash itself, particularly the +ve supply to the ignition bulb (not the lead back to the alternator). This supply also works the dash bulb test at ignition. However If you do have a good battery and it goes flat on its own, the usual fault is a bad alternator rectifier diode. You will need an oscilloscope to check that out, which you probably don't have. Take another's advice and take the car to a proper auto-electrical/alternator exchange shop. They can test it easily, even if it costs a small amount. Unreliable is just that, and you need the car to get you there and back. ABS sensors. Why is the guy not suggesting that you change all 4?. They all go into the same box of electronics. I had a low output sensor on my car for years. As long as the amplitude is big enough for the ABS ECU to detect, it doesn't care. Its looking for the waveform stopping (i.e. wheel locked up). If you have a scope (again sorry), and the circuit diagram showing which wheel attatches to what pin on the ABS ECU (sometimes referred to as a brain), you can jack each wheel up, spin it and see the waveform at the ABS ECU on its connector plug. If you have a low output, its most likely due to a bad connection between the sensor and the ABS ECU, or the sensor is not properly seated in its hole (or dirty or the toothed wheel on the hub dirty). If you do get a new sensor (singular !!), see if you can get one from one of the alternative Merc bits suppliers. There seems to be a number of them in the UK

Merry xmas

Hello

Just checked Eurocarparts. Your man is quoting their price not the MB price. £90 each (more or less). Ouch.

Better it be just the one then if it does need replacing?.

Cheers... Rob.

snip

hi there the new battery did last most of a week, and it was under pretty extreme use so I think the drain may well have been enough to flatten it, seems to be behaving better now, at least under more 'friendly' driving conditions. The alternator tested out ok at the sparky's, and it shows about 14V on a cheapo meter now, so its probably within spec and I couldn't detect any drain when I retested myself (same meter though...) but I am definitely going to have to go in and check behind the dash. Hopefully the charging is up to snuff now The ABS only has three sensors - four is traction control I believe -the guy said the two need to have similar resistance, and a 20 year old one is fairly unlikely to match a brand new one, which made sense to me. I've cleaned the business ends of the sensors - pretty messy, and cleaned all the contacts I could find but I will try cleaning out the gear properly, that's a good thought.I've found a few places with second-hand ones at about £60-70 a pair, but I will try the local scrappy's and see if I can find a close enough donor, should work out cheaper if I can pull them myself, though it would be nice to be able to test them somehow, measure the resistance I suppose

cheers

Happy New Year!