Disco 2 Nanocom fault codes for wheel sensors.

I've slowly been tackling niggling problems with my project Disco and I'm down to ONE fault code.
24-08 "Rear right wheel sensor output too low" according to Nanocom.

A bit of history:
Fitted brand new hubs to rear axle as part of the build.
Replaced standard cables supplied with the hubs for brand new front ones as they're much longer (it's lifted).
Had trouble codes for both rear sensors, cleared, came back.
Changed nearside cable back to short one that came with hub. Codes cleared on that side.
Changed offside cable back to short one that came with hub. Still have the one code as mentioned above.

I just wanted to get some advice before I strip down the brakes/hub etc for the Nth time as I'm getting pretty frustrated with it now.

Firstly, what would cause the output to be too low? Is it the distance of the sensor from the toothed wheel?
Both hubs came with various sizes of shim already fitted to the sensors. Would it just be a case of maybe there are too many shims and I need to remove one or two?

Has anyone else had this problem and how was it sorted?

First of all nanocom used to mix up the position of the sensors from time to time or even give false codes from SLABS... so, erase the code, unplug the RR sensor and see if the code changes to open circuit or not, select "inputs" and see if the stationary voltages are confirming that the RR is lower... the system passes the self test if the voltage inputs are all between 2 - 2.3V if one is out f that should trigger a code, if the tests are confirming that it's really the RR sensor you have to unplug and measure it's resistance with multimeter to make sure the winding is OK which means between 950 - 1100 Ohm, if it's out of that range you need a new sensor... if it's OK the same resistance measurement at connector C0378 pins 3-4 and ECU input pins for that sensor(C0503 pins 1-2)...if you can't read the diagram and connector views find somebody who can cos it's too hard for me to explain here if you are not familiar with electrics and RAVE files... the air gap is irrelevant in this case

Thanks for the info sierrafery.
So this morning I've done the following so far:
Cleared codes.
Unplugged RR sensor.
Read codes again and got "RR sensor electrical failure" and "RR sensor output too low".
Cleared codes.
Plugged sensor back in.
Read inputs: RR sensor voltage 2.17V. All the others read within a few hundreths of this. All wheel speeds 1.7Km/h.

I'm afraid I don't have a multimeter so I can't do the other checks.
As the fault only shows up when driving could this point to the hub being faulty if the sensor seems to be OK?

Andy Warren said:

Hi, did you get this sorted out ? When I used mine on my son's TD5 after he converted it to springs we had no such problems.

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yes, seems that the code points to the right sensor then and as the stationary voltage input is ok the problem is with the hub

DefenderPilot said:

As the fault only shows up when driving could this point to the hub being faulty if the sensor seems to be OK?

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this was the nugget of information we needed!
If it only turns up when driving then yes the hub needs changing as the speed read by the SLABS is irregular or faulty. The gap between sensor and the reluctor wheel is out or going in-out-in-out.
You may not be able to sense the play even with the wheel on, but it only has to be out 1/2 a MM.

By the way, a multimeter only costs a tenner! I use mine all the time, as you will once you get one!

Thanks people. I've ordered a new pair of front hubs as the rear sensors come with far too short a lead for my lift. Have also ordered a complete new set of bolts to fit them with as I used the old ones when I last changed them. Hopefully this will put me much closer to getting that MOT. Only a few small jobs left to do.

Oh, and I think it's probably time I got with the times and get myself a multimeter. Any recommendations? I know nothing about them.

DefenderPilot said:

Thanks people. I've ordered a new pair of front hubs as the rear sensors come with far too short a lead for my lift. Have also ordered a complete new set of bolts to fit them with as I used the old ones when I last changed them. Hopefully this will put me much closer to getting that MOT. Only a few small jobs left to do.

Oh, and I think it's probably time I got with the times and get myself a multimeter. Any recommendations? I know nothing about them.

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Don't forget you'll need a couple of the big O ring seals as the front ones don't need them. You'll also find the fittings on the sensor wires are nothing like the ones on the rear and will not fit easily into the hub etc.
I know this cos I got sent one once accidentally and had to use it as I was in a hurry.
Personally I would get ornery rear ones and extend the two wires to suit. But others may tell me off. You will at least have wire from the old ones to use which will have exactly the same cross section.

The fitting kit I bought has the O rings as well. My build is extremely non-standard and I've made brackets to suit front sensors on the rear.

DefenderPilot said:

The fitting kit I bought has the O rings as well. My build is extremely non-standard and I've made brackets to suit front sensors on the rear.

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Fine!
I just found the moulded on bits of black plastic type stuff more or less got in the way and I had to make my own mount for where the wires come out of the hub, also to protect the sensor.
In the end, the left front went fubar, so I replaced it with this one, which fitted fine and replaced the rear left with the original which was in fact OK although a local indy had told me it was the problem.
It turned out to be the right rear that was the problem.
Wonder if they used a Nanocom.

Just to confirm the front hubs (D2) DON'T use the o-rings but the rear hubs do.

Stanleysteamer said:

Don't forget you'll need a couple of the big O ring seals as the front ones don't need them.

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all D2s left the factory with o-rings on ABS sensors as they have it by default so your statement is maybe valid for bodged up vehicles.... see the pic how a front wabco sensor is equipped https://www.ebay.com/itm/370519386816 .... and that's how it's normal, IMO removing that o-ring is silly

sierrafery said:

all D2s left the factory with o-rings on ABS sensors as they have it by default so your statement is maybe valid for bodged up vehicles.... see the pic how a front wabco sensor is equipped https://www.ebay.com/itm/370519386816 .... and that's how it's normal, IMO removing that o-ring is silly

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You misread my post, I said BIG O ring seals, i.e. the ones that keep the oil in, on the rear hubs. Not the little ones that are on the sensors. They, the little ones, are or should be present on all 4 hubs and without them I cannot see how the sensor would work properly or indeed keep the axle oil in!
When I ordered a rear hub, they sent a front hub by accident. that was OK except it came without the big O ring as you would expect. So they then sent me a big O ring seal and that worked fine, on the rear.

sierrafery said:

all D2s left the factory with o-rings on ABS sensors as they have it by default so your statement is maybe valid for bodged up vehicles.... see the pic how a front wabco sensor is equipped https://www.ebay.com/itm/370519386816 .... and that's how it's normal, IMO removing that o-ring is silly

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Hi, I was referring to the hub to hub carrier o-rings FTC4919 fitted to the rears only & your right the ABS sensor o-rings should NEVER be left out.

Stanleysteamer said:

You misread my post, I said BIG O ring seals, i.e. the ones that keep the oil in, on the rear hubs. Not the little ones that are on the sensors. They, the little ones, are or should be present on all 4 hubs and without them I cannot see how the sensor would work properly or indeed keep the axle oil in!
When I ordered a rear hub, they sent a front hub by accident. that was OK except it came without the big O ring as you would expect. So they then sent me a big O ring seal and that worked fine, on the rear.

Click to expand...

Andy Warren said:

Hi, I was referring to the hub to hub carrier o-rings FTC4919 fitted to the rears only & your right the ABS sensor o-rings should NEVER be left out.

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My apologies... i wasnt so concentrated on the text as the discussion was about sensors and "derailed" to hubs and related o-rings which is other subject

Just a quick update to tidy this subject up nicely.

I've dragged myself into the 21st century and bought a multimeter. Just a cheap one but should do me for the basics.

Changed the hub for a new one complete with new sensor and no more fault codes.

DefenderPilot said:

Just a quick update to tidy this subject up nicely.

I've dragged myself into the 32st century and bought a multimeter. Just a cheap one but should do me for the basics.

Changed the hub for a new one complete with new sensor and no more fault codes.

Click to expand...

Very glad to hear that the new hub fixed the problem. Bet you couldn't feel the play in the old one, I couldn't!