TD5 ABS light

On my Disco TD5 (99 V reg) I have a ABS TC HD light fault, previously when under warranty this was cured with a new wheel sensor. So this time I worked
out which was faulty by applying the brakes on a muddy road and checked to see which wheel locked up, also tried to spin the wheels and see which wheel the traction control left alone, each time it was the front passenger wheel. I then checked the resistance of the sensor and it was open circuit, all the others measured around 1000 ohms. Landrover parts dept say the sensor is not available on its own but as a complete item with a hub assy for around 270 however if you question them they will look on a different page of the parts manual and hey presto the sensor is there for 47! so I changed the front passenger side ABS sensor, but the fault is still present! The new sensor reads 1036 ohms and can be measured at the SLABS unit, if I spin the wheel I get about 20mv P/P from the new sensor but the other wheels when spun will generate around 150-180mv P/P (measured with a scope). Now the question is do Landrover have somone matching up the wheel sensors to hub assemblies (not very practical) or have I missed somthing? I can't see that L/R would have changed the sensor spec (both have the same part No and are made by Wabco) I dont really want to fork out 270 for a front hub assy and find the fault is still present or book it into L/R and have to admit defeat with what appears to be a simple problem! So as anyone experienced this before and can you point me in the right direction to cure the problem.
Very confused Dean
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It sounds to me like the air gap may be incorrect.... the LR workshop manual simply says... "ABS sensor is supplied fitted to wheel hub and must not be removed." On a Discovery 1 you just push the sensor in until it touches the exciter ring and it gets knocked back into the correct position when you first drive it. I'm not familiar with the Disco II but it seems that the exciter ring is built into the hub and the gap is set at the factory, hence the complete unit scenario. On a Disco 1 the ring is also available seperately. If you have the LR part number for the sensor you have I can look it up and see what vehicle(s) it's supplied for as it may be a Disco 1 sensor.
In theory you may be able to set the air gap (position the sensor) using your scope but as you're not supposed to take them apart I have no idea how much room you have for adjustment. On the Disco 1 the actual air gap is very small.
You might want to give a none franchised LR specialist a try as they have often come up with ways around this sort of thing in the past. Without wishing to sound like a stuck record, I know Maddison 4x4 are worth a go but it depends where you are.... http://www.maddison4x4.com/ Even if they are too far away to visit a quick phone call may offer a solution and they may be able to do the complete hub cheaper than a franchise dealer too.
cheers
Dave W. http://www.yorkshireoffroadclub.net /
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Deano wrote:

Hi Dave,
Thanks for the info, we now have loads of signal coming from the front sensors. On the TD5 the sensor is an encapsulated device with a single mounting lug that just bolts into the hub , (part No TAR 100060) in the L/R service manual it describes the replacement procedure as unbolt and bolt in the new one, however if the surface of the hub is corroded in any way then the new part will not seat correctly and distort the shape of the mounting lug! the air gap is so critical, so when fitting mine I had distorted the shape of the mounting lug and reduced the signal to an unusable level. just a matter of reshaping the lug, clean off the rust, put the 'I'M ring down the hole, apply a small amount if lubricant (supplied with sensor) and refit, simple eh? Just need the error codes taking out of the SLAB unit. I also cured a pig of a fault with the rear seat locking mech but my knuckles haven't healed up enough to type that!
Regards
Dean
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