Hi, i'm not exactly sure where to post this so I thought that here might be a good place to start.

I was coming home last evening, bumbling along on a quiet motorway, doing about 50 mph, when the message "ABS has failed", or something similar, and the yellow ABS light and the traction control lights came on and stayed on until I got home. The vehicle didn't appear to have any problem driving along, but obviously there is some issue.

Perhaps someone could give me a bit of advice on the problem. It is starting to get tiresome, at this stage, the constant problems which are now happening. The heater matrix and blend motors were replaced only two months ago, then the drivers side latch packed up, and the car has driven maybe 300 miles, and this includes a journey to a wedding this weekend. Now the ABS fault has appeared.

I know, also that I will need to replace the height sensors shortly, as the EAS has been, since getting it back from the garage two weeks ago, going to full height when I go around a roundabout fairly quickly causing the vehicle to lean somewhat. Then I have to press the EAS switch to drop the vehicle back down, after which the vehicle runs fine.

But firstly I need to solve this ABS issue, so any help would be appreciated.

Edit - having read through a lot of different forum posts about this, could it be so simple as a wheel sensor ? Maybe I just need to buy new height sensors and get hold of some Wabco wheel sensors to cure the problem.
Edit - I plugged in Nanocom and the readings from the sensors are - front right 2.31; front left 2.35; rear right 2.21; rear left 2.35. Perhaps someone might know if these are correct, or thereabouts.

Another problem seems to have cropped up, now. The gearbox cooler fan is running when the ignition is turned on. This is a new issue, it has just appeared this morning. The car has been parked since 10pm last evening so it certainly can't be hot this morning. Does anyone have any idea what could be causing this ?

Pierre3.

Are those Nanocom wheel sensor readings while standing still? What you need to do is start looking at them and then very slowly start driving forwards. All should start to read at the same time and will rise at a steady rate. Any that are sluggish in starting or read different to the others, is the faulty one.

Hi Richard. Yes, I took those readings while the car was parked in the drive, this afternoon. So, I will follow your instructions tomorrow, and see what they are then. But does this dashboard message, and the ABS and TC warning lights, just indicate a likely wheel sensor issue ?

Also, do you have any idea why the gearbox fan keeps running ? Is this likely to be a stuck closed sensor ? I have done some "research" on the squinty-net and it looks like a stuck open heat sensor is the problem. Maybe my best option is the change the sensor, and not have the fan motor go west !!

Pierre3.

Yes, you need to do the test moving but the Nanocom will disconnect as soon as you hit 5mph (a 'feature' of the Wabco system, not the Nanocom) so you need to trickle along slowly. Any fault with the ABS will also cause a Traction Control fault as the TC uses information from the ABS to detect if a wheel is spinning or not.

Can't help with your gearbox fan as only diesels have it, a V8 has a much larger cooler so doesn't need a fan. It doesn't seem to appear in the ETM although there is a description of how it works.

I had this issue for a while, and when I went to tackle it, I discovered that I had a bad bearing in the right front hub.
This allowed the wheel to wobble ever so slightly under a certain set of conditions.
This wobble was enough for the reluctor to just nudge the sensor far enough out that it was too far away.
I had been chasing the issue as a bad sensor and tried several, all of which fixed the problem temporarily, then
it would re appear. Try giving each one a tap to re seat them, and see if it solves the issue.
At no time in my 6 months of troubleshooting did the Nano ever report an ABS or TC error, so I was really baffled.
Simple check, is jack up each wheel and give the thing a good wrestle in out and side to side looking for any play.
I was astounded at just how bad the bearing had become with no other symptoms noted aside from an occasional
slight wobble I put down to road surface or tyre issue.
Good luck!

Hi guys, thanks for your advice. The information from Bolt is interesting, especially as steering play is nearly always there. I will try the obvious solution - tapping the sensors to make sure that they are fully in.

OK, so an update to the above - I checked the readings with Nanocom, and Madame writing down the figures, and I got more inconsistent results from the front left sensor, compared to the other three sensors, and compared from a standing reading. So a few taps with a light-weight hammer and the issue appears to have gone. I took the vehicle for a drive around the block, about 1/4 mile, and the issue has not yet re-appeared. So a good result, and thanks to Richard and Bolt for the varied advice.

Now I need to address the gearbox oil fan sensor. I looked up how to change the sensor and most posts suggest that the front bumper has to come off, but I had a look under my car to see how difficult it is going to be, and my front bumper fixings don't look anything like the ones on the internet. It was suggested that behind the bumper there are two bolts to be loosened, and then you knock the bumper downwards and the it will pull out forwards. Well, good luck with that because the radiator is in the way of any access to the back of the front bumper bolts.

I will need to investigate this more, and see if I can find clearer instructions relating to the front bumper on my vehicle. First stop RAVE, and hopefully a clear description - when I can find the section dealing with it !!!

Pierre3.

Section 76 - Chassis and Body - Repair, page 10 onwards. There's no bolts that are obscured by the radiator, the bolts are in from underneath.

Richard, thanks for the RAVE page number. And after reading your post I went back out, got out of my electric wheelchair and lay down on my remote control inspection trolley, and rechecked the front bumper - where I found two hex head bolts. As I didn't have a hex head driver with me I decided not to remove the bumper on my own. The danger of it falling on my head and bringing me back to sanity was tempting, but I decided against this course of action.

On a more serious note, when I had a look at the gearbox oil cooler fan it looks as if I could remove it by undoing the phillips screws that hold the small fog light grill in place. The grill seems to be right in front of the fan sensor and it does look as if I remove the grill then the sensor should be right there, hopefully with enough manipulation space to remove it. First job I will attempt is getting the fog light grill screws out.

Pierre3.

Nah, when you lay underneath and push the bumper forwards, it lands on your stomach.....

Ha, that's fine then. Provided it lands on the two ends then I will be able to crawl out from under it !!!