Method of checking wheel speed sensor fault

[LandyAndy]

Hi Guys
Chatting to my Bro the other nite about my 3 amigos problem.
He said he has a stuffed(due to prang) falcoon hub with ABS sensor still attached.
He put his multi meter on it and found that it registers a static ohms value which changes when you rotate the hub.On a win here I thinks!!! I consulted the RAVE CD.Found that the D2 should register 950-1100 ohms resistance on the wheel sensors.All mine were slightly above the 1100 ohms static but not by mutch.BUGGER as I was hoping to find 1 open circuit!!!.
Did the test again,this time turning each wheel and registering the ohms,definately fluctuated heaps for each wheel as the wheel turned then settled to the start value.This tells me my wheel sensors are OK.
Im ready to do the same check on the SLABS ECU but I would like to see if you 2 that have the same problem at the moment get the same result or different(PM coming).
My next check is to test the readings at the SLABS,got all the info from RAVE but would love to hear at least one of you that you find a fault/no faults in a wheel sensor via the first method before I proceed.
Im not going to do any further tests to you 2 get in touch!!!!
Just hoping to draft out variables,the tests Ive done sofar wont hurt your ECUs.
Please try asap!!!!
Andrew

[Lucus]

Did you check for a voltage fromt he sensor while you rotated the wheels?

Edit: Im an idiot. You can't test voltage in a 2 wire speed sensor. Is your brother able to test frequency with his multimeter?

For what its worth my 93rrc had ongoing abs and tc faults codes IE wheel sensor air gap to big, brake pedal position sensor error. I check and readjusted and check again and keep getting the same faults. I was also getting codes popping up that wherent on the list. I read on the net about replacing the abd ecu and pump relay and i did that all cleared the codes and they havent been back in almost 12 months

[Blknight.aus]

to save a little time and effort grab a patch of gravel and when the tc/abs/hdc combo is on hit it at a medium sort of pace and then peg the anchors... Abs will work on the 3 remaining wheels or on the axle that doesnt have the ABS fault depending on which ABS brain you have....

Big red is having intermittnat ABS/TC warnings and its the front right wheel Rover com says so and funnily enough thats the one that locks when I get into the brakes hard enough....

[LandyAndy]

Dave my ABS TC and HDC lights are on.
Hoping the others with the same prob can eliminate my probs by working thru my findings
Andrew

[Blknight.aus]

dont forget that the sensor fault may not be the sensor but the harness and plugs prior to the sensor.. Big reds Im fairy certain is in the loom as I can make the fault appear at will by grabbing the wiring and giving it a shake while the ignition is on.

[LandyAndy]

I did the skid test,found that the right rear skided.
OK decided to clean that sensor again,jacked up the rr with the trolley jack pushed the garden hose up where the sensor wire goes and turned the wheel whilst the water was running.Started the car up eased it into gear,speedo works!!!!.
Then repeated the same on the left rear,NO SPEEDO!!!!! found the culprit,the left rear sensor or a wiring fault for the left rear sensor.The fronts both made the speedo work.
The speedo reads 120kmh at idle in fith!!!!!.Confused!!!!
Andrew

[Blknight.aus]

that sounds like a dud sensor, the computer averages out the wheel speeds to get vehicle speed and ignores any that are obviosuly telling fibs.

If you can get hold of a meter that can impersonate a cro use that and compare a good sensor to the bad one...

[LandyAndy]

All 3 that worked gave the same speed reading.
Andrew

[Blknight.aus]

ok lets try wording that differntly (my bad)

With the vehicle off of the deck spin up a wheel and then using a CRO look at the output of the sensor.

Then compare good to bad... (you'll be looking at the wave output of the sensor not what the speedo indicates)

[Pedro_The_Swift]

hm,, ok.

just the fact that the speedo doesnt work for THAT wheel is not enough?



gotta buy a trolley jack:angel:

[LandyAndy]

Hey Pedro
Now you have discovered WHICH wheel isnt working for you can you do the skid test and see if the OPPOSITE wheel to the non working wheel sensor is the one that skids as mine did.It will help with others later if we say skid your cars wheels,the opposite wheel sensor is your problem.Also what sort of speedo readings did you get??? Mine were 4 times what the single wheel should be reading for the same rpm in 5th at idle,a tad harder to check in your self shifter,but you should have a rough idea.
Hope you get hold of a sensor from the supplier I mentioned in the PM,I didnt want to know what a newie is worth!!!!
Andrew

[Graeme]

The speedo reads 120kmh at idle in fith!!!!!.Confused!!!!
Andrew
That's about right. 120 divided by 4 (ony 1 of the 4 wheels is turning so its travelling 4 X as fast as it would normally) = 30.
5th gear 40kph / 1000rpm = 30kph for 750rpm.
I'll buy that.

[LandyAndy]

That is my thought too Greame,it was suggested by a member that a wheel sensor reading that sort of speed is faulty,the same person also suggests that the skiding wheel has the faulty sensor.My opposite on the same axle skids.
Was hoping Pedro discovers the same as I have so in future Pedro and myself can pass the correct info on to D2 owners as its such a common fault.
Ive got a secondhand sensor coming,will see if it fixes everything.
Thanks
Andrew

[Graeme]

It would be good to determine a rule for identifying which wheel is the culprit. But having a wheel doing 120kph whilst idling on a block is a bit scary. Maybe 1st gear is a safer option.
Good luck with the research.

[Pedro_The_Swift]

hmm, I must be getting old,,
I just let in idle in D
:angel:

and it read,, oh around 20kph??
or should I say 3 did.

will need a spotter for the brake test,, so it might have to wait till the weekend,,

[Blknight.aus]

Seems like I need to look at how i present some of my info.....


I did the skid test,found that the right rear skided.
OK decided to clean that sensor again,jacked up the rr with the trolley jack pushed the garden hose up where the sensor wire goes and turned the wheel whilst the water was running.Started the car up eased it into gear,speedo works!!!!.
Then repeated the same on the left rear,NO SPEEDO!!!!! found the culprit,the left rear sensor or a wiring fault for the left rear sensor.The fronts both made the speedo work.
The speedo reads 120kmh at idle in fith!!!!!.Confused!!!!
Andrew

When i replied

that sounds like a dud sensor, the computer averages out the wheel speeds to get vehicle speed and ignores any that are obviosuly telling fibs

to that I was intending that to mean that the sensor that wasnt giving a reading was dud and that under normal circumstances the computer will average out all the working sensors (for when your cornering or have a wheel spinning/slipping)

[LandyAndy]

Hi Dave
No agro intended.
From Pedros/mine and anybody who can hop in with the same issue. Im hoping to stay to others in the future,do a good skid in your D2 note the skidding wheel.Go to the shed jack the opposite wheel on the same axle and discover no speedo reading.Then repeat for the others and hopefully find that the other 3 have the speedo working.
The problem then lies with the sensor with no speed reading despite passing the resistance value.Wont know till I replace the sensor I belive is faulty,but all seems to make sense,
Is the Defender a true 4 channel ABS system as the D2 or just front rear 2 channel ABS as other cars have???
Andrew

[Blknight.aus]

no aggro intended I reread it then had the wife read it and she mis-interpreted it the same way.. so rather than edit I had a crack at trying to explain it properly

ITs a true 4 channel abs as it uses the same sensors to control traction control and the ABS/Tc pump block has 4 seperate oulets, one for each wheel..


but I have a theory on the wheel skidd thing...

what if a faulty sensor on one wheel disables that axle. then it will come down to normal physics as to which wheel will slip first. the non effected axle will have abs so wont slip but the effected axle will be a different story, what If I jagged it to get the wheel with the crook sensor to skid and you hooked it the other way?....

[Pedro_The_Swift]

just pulled the sensor out,,,
and everyone can stop thinking "a good hose out" will fix this:p

some iron type filings on the end, but thats all, end was clean otherwise.
cleaned and replaced and made no difference,,

am ASSUMING I will be doing a brake test around lunchtime today--

[Pedro_The_Swift]

cant see why one faulty wheel sensor would disable both sides-- isnt this why we have 4way ABS?
(the above sentence contains no actual knowledge of how 4way differs to 2 way or hiway ABS:D)

[LandyAndy]

Hi Pedro
How do you pull them out????
Havent tried yet as Im waiting for a spare one to turn up.
Andrew

[Pedro_The_Swift]

t'is easy!
remove wheel, caliper, hub, small allan screw,
gently pull sensor up and out,,

I'd have a stiff brush handy at the allan screw stage and clean up the area around it before removal.

should release with a gentle suction "pop"
there is a small o ring-- dont lose it!

[Pedro_The_Swift]

Hey Pedro
Now you have discovered WHICH wheel isnt working for you can you do the skid test and see if the OPPOSITE wheel to the non working wheel sensor is the one that skids as mine did.It will help with others later if we say skid your cars wheels,the opposite wheel sensor is your problem.Also what sort of speedo readings did you get??? Mine were 4 times what the single wheel should be reading for the same rpm in 5th at idle,a tad harder to check in your self shifter,but you should have a rough idea.
Hope you get hold of a sensor from the supplier I mentioned in the PM,I didnt want to know what a newie is worth!!!!
Andrew


That is my thought too Greame,it was suggested by a member that a wheel sensor reading that sort of speed is faulty,the same person also suggests that the skiding wheel has the faulty sensor.My opposite on the same axle skids.
Was hoping Pedro discovers the same as I have so in future Pedro and myself can pass the correct info on to D2 owners as its such a common fault.
Ive got a secondhand sensor coming,will see if it fixes everything.
Thanks
Andrew




am ASSUMING I will be doing a brake test around lunchtime today--



OK,, so several brake tests done and witnessed by reliable mate,,

the only wheel that locked was the wheel that DID NOT produce a speedo reading.

felt a reduced ABS pulse during each test.



cheapest sensor I can find is 175 from andersons in hervey bay,,,,,,335 from LR

anybody got any other suggestions??
testing OR pricing?

[LandyAndy]

Try Bundalene on Ebay.
Ive got a S/H one on the way.$55 inc ph.
He has more stuff than advertised,find his ebay shop and email a question.
Nice helpful person.
Andrew

[Pedro_The_Swift]

yea,, already have;)

and ---- no.
has lots of D2 electrikery but not a front sensor,,,

[LandyAndy]

UNFORTUNATE!!!!!!
Try Karcraft,inc postage they are always pretty good.
Andrew

[WNE Me]

Hi Gents
Just logged on to see if anyone has had this problem, it seems to be quite common. As a matter of interest my 2001 D2 has done 206,000km. Is this ABS fault a sympton of age or abuse? Or just another Landy built in headache. :mad:

[LandyAndy]

Fairly common.
Off-roading seems to make it worse,mud/water/dirt seem to make maters worse.
Andrew

[Pedro_The_Swift]

Andy I cant see how anything would get in there,,
from my small look it seemed a sealed part of the hub that the sensor uses to read off,,,


maybe heat???

[LandyAndy]

Ok
Fitted secondhand sensor.
Same problem.3 amigoes and no speedo reading from that wheel.
The secondhand one reads just outside the recomended value(950 to 1100ohms),1130 ohms.My other 3 that do work the speedo read similar values.ie just over 1100 ohms.
Im getting the same ohms reading at the SLABs ECU input for that wheel,the value also changes if the wheel is rotating indicating that the sensor is OK(in my opinion).
All fuses connectors checked.
Starting to belive there could be a fault/dry joint in the SLABs connection.
BlkNight Dave,this could explain your ability to induce the fault in yours by wriggling the harness.
THOUGHTS PLEASE PEOPLE!!!!
Thanks
Andrew

[Blknight.aus]

with mine the harness part thats faulty is between the axle and the chassis I suspect that over time repeated flexing of the suspension causes the wire to go stiff and fracture inside the insulation inducing noise or open circuts that send the system haywire. This is why I suggested the cro test with a portable setup you should be able to plug it into each cabling set and (have a passanger) watch it on the move.

[JohnE]

Andy,
i never admit to being an expert but have a similar thing with mine. As dave said he wiggles his loom and gets the fault, i jiggle the sensor wire and get the same, it is intermittent. Need three hands to find it when using the multimeter.
the conclusion its the sensor wire between the connector and the sensor.

There was a really good post ages ago on how to fix a dry joint, and i believe it had all the , how to tell what it is clues. by can;t remember now lived near the gong and now is in qld, was it Stevo?

hope this helps as well


john

[Jezza the Geo]

Well, folks, I've repeated Andy's efforts here (without replacing a sensor) all sensors seem OK and the speedo trick brings no joy. Some iron on the sensors, but cleaned off readily.

I have constant three amigos though. Now - other strings indicate squealing brakes (which I do have) and the pads are definitiely not genuine, so I'm hoping that is the cause of the problem.

Otherwise, another bloke in this area had a faulty set of valves. . . This Three Amigos is proving to be a right pain in the Toyota! A bit more fiddling yet

[LandyAndy]

I read on one of the UK sites that if the 3 amigoes trio are tripped 3 times and the fault is still there (ie hasnt self rectified)they will stay on until cleared by testbook or similar even if the fault goes away or is repaired.
Could account for some(on the UK sites) that replace parts but still have the lights,a clear of the computer and all dissapears without a real answer.
My next move is a computer clear then possibley look at the SLABs for a connection problem
Andrew

[knp]

Ok
THOUGHTS PLEASE PEOPLE!!!!
Thanks
Andrew

I found this some time back and have been reading with interest and waiting for a chance to attack MrC but his lights have stayed off now for several months. Have you seen these?
http://www.aulro.com/afvb/technical-chatter/33951-shuttle-valve.html
http://www.aulro.com/afvb/technical-chatter/34480-shuttle-valve-switch-has-arrived.html

Also came across some more info from somewhere but these are at work and will post it soon. Something about properly bleeding the ABS unit etc using the test book and the possibility of stale brake fluid also being a contributor.

Anyway those links above from Stevo have some excellent troubleshooting and I assume his problems have gone away now?

HTH
Peter

PS FWIW the lights in MrC seem to only come on when I hit a large pot hole. They also seem to be affected when I wiggle the wiring loom for the ABS module/controller/? in the engine bay. That's as far as I've gone for the moment.

[Pedro_The_Swift]

just to continue this,,
fitted second hand sensor,,
no change.

Had the Amigo lights reset at Bundaberg,,
as far as I can tell,, on my grass skid pan,,, all wheels ABSing.


will jack it up and test it.

invoice said (according to Bundaberg there is NO printout from this system) erratic error from front left and error from drivers pretensioner.
"recommend replace both"

[Pedro_The_Swift]

front left now does 45kph at 1000rpm

:D:D:D:D:D:D:D