abs light is showing

[NGOLF.U]

hey guys is there anything i should be looking for.

i have been hearing a rattle in the engine somewhere sounds like a piece of metal has come loose. only hear it when i go over bumps or make quick turns.
could this be the reason why the light has come on?

thanks

[Tim]

scan the car for codes it should tell u what the error is about.

[99gti]

Did you get it sorted? I know there is a sensor for the ABS in there and I have heard of it being un-plugged giving the same results. Did you get a chance to scan it?

[NGOLF.U]

yeah found that the surroundings of one of the cables on the rear break was ripped exposing the wiring inside the cable. I taped that up and its all fine. I didn't scan it. The rattle was loose intercooler support.

[99gti]

Now I have the same problem but a slightly different scenario.

After we fitted my rear wheels we took it for a squirt. By the time the wheels had made their first few rotations, we had the ABS light up along with the flashing red exclamation light. We scanned it for errors straight away and it threw a code for both rear ABS sensors. I dismissed it due to the difference in the size of the wheels meaning bigger rotational circumfrance.

But - the plot thinkens! Driving home today from work someone pulls up next to be and says I have no break lights at all!

It's too dark now to go and check fuses atc but my tail lights all work. Would it disable the rear breake lights if the ABS was confused? The ABS seems to have disabled itself atm, but comes back on when I start the car up after a rest.

Is turning on cruise control enough to prove the break light switch is ok?

Any other ideas or suggestions?

[99gti]

Ok, so cruise control works, and hitting the breaks stops it. If I anchor the breaks hard my wheels lock up so no ABS, and I'm throwing a code for the ABS control unit now as well. Could running the larger wheels on the rear have fried my ABS control unit?

Does the ABS control unit also control the rear break lights?

Thanks gurus!

[h100vw]

I doubt the difference in wheel diameter would damage the ABS ECU. It would be confused by the difference in signals it sees at each end of the car. There would normally be only a small difference in output between front and back of the car.

The signal would be a sine wave under normal circumstances. The ECU can detect when that drops to zero, wheel locked, or falls in frequency due to being much slower than the others. This would indicate onset of a lock up.

The system may well self test satis on start up but fail as you set off. I had this on a G60 and never looked into it.

What is the exact code the ECU is giving? I'd google that and see what comes up.

Not aware of the ABS controlling the brake lights, doesn't make sense for it to IMO. Like you say the systems fails safe so you still have brakes but no anti-lock.

Gavin

[qsilverza]

Could be your Brake Light Switch ? Cheap and easy to replace.

[Golf Loon]

Yeah brake light switch common to fail on G4s.

[Jmac]

Brake pedal switch for sure , just fitted one today on an A4 B6 similar set up and the Abs lights were on. Careful when fitting them though , done heaps, you must not be tempted to adjust the new switch to the length of the old one that will stuff it. Dont touch the pedal either just fit in the hole , push in and turn till it clicks -job done self adjusted the works. Funny thing the Porsche cayenne has exactly the same switch with 1J0 golf 4 part number. Geez when i was working for them they didnt enjoy knowing this. Switch from Porsche is around $90 and same thing in a different box is $35 ish.
Just remember not to fiddle with the thing and you will be sweet.
Jmac - Sorry about the useless Porsche info ( they are still in the family though)