TRAC OFF illuminated
 

It must be the season for it, my car is testing my patience and my wife keeps saying "told you not to get another GV!"

Anyway, I've now got the TRAC OFF constantly illuminated. It came on whilst sat at traffic lights the other day (2 minutes into a journey) and stayed on.
When I stopped, I checked temperatures and didn't feel excessive heat coming from the brakes.
Next ignition on, the light stays on from immediate start-up, so I think that eliminates overheat on the brakes switching the system off.

My next though was the wheel rotation sensors, suspecting one of them is faulty/giving back faulty/no readings so the ECU is disabling the system, does that sound plausible? In which case this weekend I'll be crawling under to try and get a multimeter reading off the rotation sensors unless somebody happens to know where all those wires feed back to in a sensible location in the engine bay?

Other than the above, are there any other areas to check that will cause the "TRAC OFF" to be on like this? (Faulty ECU is always possible, but no other functions are showing faulty)

1st to eliminate would be ABS sensor Andy lad

1+2

I thought that at first, but I'm not getting the ABS warning light coming on, this is purely just the TRAC OFF light?

- agreed Andy, I too would expect an ABS light in tandem
- but I have seen it where the TRAC comes on [OFF] before the ABS is fault registered

In any case, cheap & easy first in the cost menu and expensive and hard last in terms of test[s]. You know where I am next Wednesday, same rules. You are having a lot of '****le' issues coming to a head, the trouble is they are not interrelated. best of luck.

I have a Trac off light from day one when I bought the GV. Also I'm getting intermediate Brake light. I checked temperatures and the same as Andy, I didn't feel excessive heat coming from the brakes. I haven't looked at the problem yet, waiting for better weather.

I know I know silly answer but have you switched it off via emmmm switch....Silly yes...
I'll go stick my head in the Snow...

Thanks QinteQ, yep my thoughts too but yes probably worth going over all the obvious ones first. Hoping for calmer weather tomorrow/Sunday and I'll have a look (Blowing a hurricane out here tonight!)

Andrips, I'll feed back on what I find, might help you track (no pun intended) yours down too.

Goggs m8, yeah if only it was just pressing the button ;-) I did try toggling the button a few times to be honest just to make sure, it doesn't budge, not even a flicker.

The default is the TRAC system & indicator light tests as ON every time the ignition switch is turned ON, even if you turned it OFF.

Thanks Andy, I'm pretty sure that mine is off because of the Brake light. Looks like if I play a little bit with hand brake cable,the brake light goes off. Maybe the sensor, but will wait for warmer weather.

Just bringing this one back up as it's nicer weather and the other night I changed the front brake pads (oops, very low!) and noticed the sensor cog was covered in rust and not in a good shape.
Unfortunately I didn't have the time that evening to clean it up and check out the hall effect sensor (If I remember rightly), but again I'd expect this to also trigger the ABS warning if the sensor wasn't showing feedback from wheel speed, etc.

But, plan is to spend a bit of time at the weekend, clean up the cog, check the sensor (I noticed passenger side the sensor wire has ominous black eleccy tape round it, which immediately makes me think bodge job... Cos I do the same!) so that's the first one to take a look into it.

My real question though, ABS and TRAC, they both need wheel speed sensing to take place? So a fault with the wheel speed sensing would trigger both faults? (Or I guess if sensor didn't return an OK, would TRAC fail and ABS not bother until it tried to operate, then perhaps fail?)

A lot of guessing, but as QinteQ says, easy bits first, bit of cleaning and testing to do.

Andrips did you get yours sussed out?

No I haven't.
I bought the ABS sensors but didn't have a chance to look at it. I went to garage to check the codes and it's come up with front left and rear left and the Abs diode on dashboard . So I bought these two sensors. I have checked the Abs diode and looks like the previous owner or some garage have removed it.

Having a little (difficult) ABS experience with the complexity of a traction-control which is inevitably part of an ABS system, probably the best way to tackle any fault in these systems is to get a scanner reading immediate. This is one area where a proper scanner can identify what malfunctions there are and if there are more than one. Of course wheel sensors and tone wheels are top of the list for failure/being out of spec.,(because of the conditions under which they work), but without the interrogation of a scanner, it's all going to be guesswork. So it might be best to stump up some cash for a reading. You should check if the scanning garage has the necessary software to do the job
This chap is selling wheel sensors on E-bay at £23:45 each.

Jeep Chrysler.co.uk Ltd.
63, Danes Rd.
Bicester.
Oxfordshire OX26-2LW.
0790 421 7035.
office@jeep-chrysler.co.uk

The wheel sensors are handed, as you see them from the drivers seat he says.

When a GV gets old, all the tone wheels are going to get rusty to some degree or other, some of the sensors could be abraided on their surface due to rust/general crud getting into the gap between tone wheel and sensor which is only in the order of 5 thou'. The magnet in the sensor is important that it be the right strength, otherwise the small output of only a few millivolts will be degraded and the "shaping" circuit* in the micro's board won't work properly to produce reliable square waves for the micro to assess the relative frequency of the wheel sensors, which is of course exactly proportional to speed. The program will then judge if any differential in wheel sensor frequency is " reasonable" (such as turning a corner) or not. Unf. the system doesn't work at all well on snow, ice or gravel, and could be said to be pointless in these conditions. Having said that, some maker somewhere might have come up with a system that WILL work under those conditions. Also, I would have thought that having the tone wheel cogs on the OUTER circumference was the worst place to have them, as centrifugal force will propel any rust/foreign matter straight into the small gap between it and the sensor. Much better to have the cogs on the SIDE of the tone wheel, the crud is then propelled at right angles to the gap.

Finally, these ABS sytems will be time consuming to fix, you might well have to change all four sensors and all four tone wheels on an older GV. All very annoying.
*Some systems have the pulse-squaring op-amp in the sensor itself. This will need a three-wire sensor. Otherwise a two-wire will only have a magneto diode in it.
Leedsman.

Looks like someone in the past has "frigged" it by removing the ABS LED?
Bit obvious. But then I can sympathize. These faults can drive a mechanic to distraction.
Leedsman.

I have sorted out the ABS issue. I changed the front and rear Abs sensors on passenger side. I can swith ON and Off the TRAC.
Still to find out the correct abs LED .

But I still have the Brake light on dashboard. Could it be because of led not working? Or I should look for something else?

Handbrake is working. Not really great but it holds the car.

I have sorted all issues related to the Brake light and ABS on the dashboard.
I replaced the missing ABS LED and it's sorted everything. (plus two abs sensors). Pretty much happy with the results.
I had a issues with rear sensor. I have Stow and go seats and you must buy specially designed for the Stow and go otherwise the connector will be different. Front ones all are the same.

I would suggest to check and replace theABS LED. It's my have loose contact or someone removed it, as I discovered.
LED is approximately 3x3mm( I think I bought the 3.2x2.8 mm and it's fit perfectly) . The voltage when I checked showed 1.98v
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