VAG-COM rear ABS codes shared between left and right????

[aclwalker 3]

Hi all,

 

I've just bought VAG-COM to help me with my ABS problems and to confirm that I have no engine faults (engine is fine, yippee) but I'm sure I remember reading on the forum somewhere, something along the lines of:

 

"VAG-COM can report rear left sensor faults even if it's the rear right sensor"...because of something that was shared between them (sorry for the vagueness).

 

I can't for the life of me find this same comment and I've tried every search I can think of to throw it up again. I never bookmarked it at the time.

 

Can anyone remember this or am I just imagining it? Is there any circumstance with the ABS in which a "rear left" code will be thrown up even if the rear right is at fault?

 

I've not started to investigate the problems yet with it but just wanted to check on this small point before I start removing wheels. VAG-COM has thrown up three faults, one on the front left and two on the rear left (don't have the codes to hand at the moment).

 

Also, I am willing to help any Corrado owners in the Glasgow area with VAG-COM should they want a demo or their own codes read. Is anyone maintaining a master list of people with VAG-COM for this purpose? I think I saw a thread for this but wasn't sure how up to date it is.

 

Thanks

[aclwalker 3]

Ooops, I guess I should have put that under "Drivetrain". Can someone move it?

[Henny 0]

moved... 8)

[Kevin Bacon 5]

RW1 one is the man for this but I can't see why the ECU would report LH faults for RH circuits and vice versa? What would be the need?

 

We need the codes. It might be that both a LH rear sensor and an LHR ABS output valve are being flagged up? There are certainly aren't two sensors on the rear wheel and VAG-COM clearly states which sensor is out, and with the correct orientation.

 

They might share the same K-Line or what ever it's called for the coding (same as Keyboards using a few wires for 52 seperate functions) but the ECU knows the difference.

[aclwalker 3]

Thanks for the reply. I've got the codes on a text file on my USB disk, but left it at home today. I'll post them when I get back.

 

I was just sure I heard someone say something about the rear sensors 'sharing a code' or something. Maybe I saw it on the Yahoo group, or the VAG-COM Yahoo group. Or maybe I was reading the forums after a night out again. :)

 

My ABS problems started immediately after I got my brakes done at the last MOT. I should have taken that car back at the time but had visions of it going back and forward while they tried to fix it, so left it to do myself, especially as it only came on at motorway speeds. However, after a few weeks it would come on immediately on turning on ignition and stay on, which is the current state.

 

After noting the codes down the other day with VAG-COM, I cleared them and retested. Only the front one came back on immediately without moving the car.

 

This suggests to me that the front one has an electrical problem since I never moved the car at all.

 

The faults for the back never came back on after clearing but have likely come back after the drive home. I'll check that tonight too, as I haven't had a chance to yet.

 

I think I need to look at the front one for either a broken sensor or lack of electrical connectivity and if my rear faults have come back after the drive home, then I likely have a problem with a rear cage.

 

I'll post the codes when I get home and any other findings. Thanks.

[dr_mat 0]

Is it, by any chance,

00276: left rear ABS outlet

 

??

[aclwalker 3]

Hi,

 

Here are the original codes. I've actually got it wrong. There were two codes on the front, not the rear.

 

00283 - Front Left ABS Wheel Speed Sensor (G47)

35-00 - -

00283 - Front Left ABS Wheel Speed Sensor (G47)

16-00 - Signal Outside Specifications

00290 - ABS Wheel Speed Sensor; Rear Left (G46)

16-00 - Signal Outside Specifications

 

After clearing, however, and driving home I now only have the first code. This code appears immediately on ignition. There is no sign of the rear problem any more.

 

Either it's not checking for any other faults cos it's already shut the system down, or the problem with the rear has gone away. Perhaps the cage has re-rusted itself into position again. ;)

 

Anyway, I checked the resistance of the front sensor at the connector on the top of the strut. (Am I right in thinking it's the end that's attached to the strut housing that I should be measuring and not the 'loose' end? I couldn't get the pins of the multimeter to reach far enough into the other end anyway...). I found that this reading was around 120 Ohms, but would go to 1 Ohm and back again. I compared with the other side and it consistently read 1 Ohm.

 

When I unplugged the right connector, I, of course, got a new fault in the right sensor which did not come back once cleared.

 

So, it looks like I have a simple front sensor problem.

 

Is there any point in investigating any further at the wheel end? Is there another connector down near the wheel or is it hard wired in and likely to be completely sheared off?

 

If there's no point in investigating any further then I'll just buy a new sensor this week and have it ready for the weekend, weather permitting.

 

Thanks for your help everyone.

[dr_mat 0]

I hope you don't mean "one ohm".. one k ohm would be nearer normal..

If it's dropping to 120 Ohms then it's obviously buggered, swap the sensor.

[aclwalker 3]

Hmmmm, I think the "1 Ohm" is actually not 1 Ohm, but simply higher than the range possible on that multimeter setting, i.e. 'infinite' if you like. It was the right hand one that said 1, but the 1 is not next to the decimal point so it probably isn't a 1. But the left one definately dropped to around 120 Ohms.

 

Just to be sure, what is the correct way to do this measurement? When I disconnected the connector at the top of the strut, I measured the two male pins that are on the part of the connector bolted to the strut mounting. Is this correct?

 

What is the 'normal' reading for a good sensor? 1 k Ohm? Maybe I should have measured on the '2000 Ohm' scale rather than the '200 Ohm' scale.

[aclwalker 3]

OK, I've just checked again and measured the other side of the connectors (i.e. the female end) and I'm getting a reading of 1045 Ohms on the good side and no reading on the bad side.

 

Seems like an obvious dead sensor.

[RW1 0]

Problem with the brake ECU, sometimes it throws odd faults as a wheel sensor goes down. As a new VAG-COM user, note that faults are stored are undated and can remain in the memory for quite a while depending on your use of the Corrado. They are supposed to self clear after 30 ish engine starts but I've yet to see that, such are the querks of the early diagnostics (all digital Corrados 1991 - 1995).

 

So some of what of you noted could have occurred as the wheel sensor went out of spec before going to a hard fault.

 

If starting to use diagnostics generally and you don't know the Corrado's fault history, then note the faults, clear the memory (and drive around for a couple of days if an intermittent fault), observe what reappears. Deal with that first.

 

In this case, yes I think you'll find it was a dying wheel sensor on the front left. The resistance check has confirmed that. The back, just check in a few days and watch the ABS light for signs of something happening.

 

Now for your fun unless the old sensor is already off the Corrado!