Result of damaged wheel speed sensor on MQ

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Result of damaged wheel speed sensor on MQ

Postby Amaroo on Sat Aug 04, 2018 6:53 pm

Hey guys, question for those that have lost a wheel speed sensor on the MQ while offroad, specifically in low range.

When a wire to one of the sensors is broken what is the result? Just warning lights on the dash? Loss of functionality of the 2wd/4wd selection i.e. stuck in low if that is when the break occurs or any other limp mode type situation?

Any first hand experience would be appreciated.

Thanks.
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Re: Result of damaged wheel speed sensor on MQ

Postby aids84 on Sat Aug 04, 2018 8:42 pm

I've come across broken wheel speed sensors where the vehicle was in 2H, transfer case wouldn't shift at all while sensor was inoperable.

Cannot confirm whether you would be able to shift out of low range if a sensor was broken, will try and test this out in the workshop during the week.
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Re: Result of damaged wheel speed sensor on MQ

Postby Amaroo on Sun Aug 05, 2018 7:07 am

Thanks for the info, appreciated.
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MQ-Broken Wheel Speed Sensor

Postby shawty950 on Wed Aug 28, 2019 1:13 pm

what happens or, better yet, what doesnt.

So 5 days into a 2 week trip from Brizzy to Alice via Sandover Hwy, down to Kulgera, Lamberts Centre, Mt Dare, Dalhouise, then Madigans Line across to Birdsville...this happens just outside Mt Dare
Click to view larger picture


What it doesn't show is the lack of 4 green wheel lights and the now flashing Orange CD light

On arriving at Dalhousie we quickly find that the rear left WS sensor looked thus

Click to view larger picture

It looks like from the witness marks, that during a bit of spirited slightly crossed up travel on the gravel/rocks of the road into Mt Dare, a rock from the front right wheel has come across, bounced off the left rear drum backing plate and then hit the sensor from the top and down towards the centre of the diff.

So what does that mean to the driveability?...well it still works the same as it did beforehand...cept the ABS, ESC and traction control are all out...the big ones are:-

1. Xfer is stuck in what ever mode/range that it was in at the time the sensor gets broken.
2. No rear Diff lock

So we tried a number of hacks, disconnecting the lead in question, both rears, pulled abs fuses, tried measuring resistance of a good sensor and replicating with of all things a welding rod, then soldering the left sensor wires to the right wires...all to no avail. Also tried turning the dial both before startup and while running to see if the ECU might do it's thing even though it was flashing it's head off...but no it was very adamant...ye must have a WS sensor or I do nuss'ink.

So, at this point, we still had approx 6-7 days of the Madigan to do and then 2 days home to Brizzy.
Decision made to order a part at Mt dare and get it sent from Brisbane to Birdsville post office, and to go ahead with doing the crossing. We were a group of three vehicles, so if it got too much could have one in front and rear to drag me across the bigger dunes.

I was just lucky that I had gone from 4H open to 4HLc before the problem struck and I also had an aftermarket Front locker to help out with no 4LLc, traction control or rear diff lock.

As it turned out, it wasn't too difficult, used the Front Locker the most in the life of the vehicle, used less fuel than the other 2 vehicles (late model Navara and Hilux) and got stuck less as well...one for me and 3 and 2 times each for the other vehicles...sometime I led and sometimes I played catch up...so it wasn't that I got the best run at the sand or went subsonic...just idled up most and used the right foot when needed..custom 3-way adjustable suspension also makes a big diff as well :D
I could have got out of mine under my own power if I had 4LLc...was just that I was leading and hesitated a bit at the lip of a dune and got the wheels buried 1/4 way and when taking off the Torque converter/load limiter cut in and wouldn't spin the wheels to get me going..the 2 Yorkshire boys lent on the rear bar and I drove it out. (Yorkshire born and Yorkshire bred, strong in the arm and weak in the head) :lol: Their words not mine.

Used less fuel in 4HLc than the other guys as well...they selectively used 4L as well...made it from Mt Dare to Birdsville on less than 150ltrs.

Anyways arrived in the Ville and the part had not left Brisbane, so out with the rear tailshaft and drove home in FWD.

Have since got another sensor on loan and shaft is back in and all good. The one that got sent from Brisbane?, aus post tracking hasn't updated since the day it was picked up 9 days ago. I have a redirection in place at the Birdsville PO to my place in Brissie and have to return it to the dealer that helped me out....when it arrives.

Engineer mate, one of the "weak in the heads" and I are looking at making up some WS sensor guards....at $400+ each for a sensor and the fact that they are at the front of the diff FFS, admittedly near the centre of the rim and protected from straight ahead forward travel rocks etc, any time you cross up the wheels there is the chance of this happening.

I was just lucky that it was 4HLc and not 4H, 2H or 4LLc...imagine coming home 2,500k's in FWD at max 55kph...kill me now...

Shawty
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Re: MQ-Broken Wheel Speed Sensor

Postby aids84 on Wed Aug 28, 2019 4:10 pm

I ripped 2 rear sensors out in the first 12 months of owning my MN. I ending up tying the leads down closer to the diff housing with a piece of elastic, have not had one rip out since. Being a old school style transfer lever setup there is no issue with the 4WD system, just no ABS and those annoying lights on the dash.

Has always been a big negative of the MQ I reckon. I'm not sure if the Pajeros that have had electronic control of the transfer case for a long time ever had these issues, would be interesting to unplug a wheel sensor on one of those and see if the transfer stops working.

I reckon the MN without the front diff actuator was the sweet spot for the 4WD sytem in the Tritons.
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MQ 4wd locked out, ABS rear wheel speed sensor

Postby lindsay14 on Wed Dec 18, 2019 11:31 am

Hi all, just sharing my recent experience with this issue.
Dash lights (centre diff lock light constantly falshing, ABS and T/C lights stay on)
Locks out 4wd and does not show up on your OBD II reader due to safety reasons i am told.
Had supercheap plug in thier scan tool and all issues were pointing toward rear right wheel speed sensor.
Issue ended up being some metal shavings on the rear wheel speed sensor.
I cleaned the sensor and put back in, disconnected and reconnected the battery and has been fine since.
As a precaution i changed out the diff oil and found some more metal shavings on the mag plug.
my mechanic (now my old mechanic) had my car for 2 days and couldn't figure this out.

does anyone know what happens to the car when the sensor has a loss of signal ?
I am thinking of carrying spare sensor and cable to the plug in future because if the wire was to ever get snagged or sensor broken off while out 4wding i am worried it would do the same thing and i'd be stuck out bush.
Probably not a bad idea to carry spare anyhow as they are fairly exposed.
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Re: Result of damaged wheel speed sensor on MQ

Postby DibbyDibbyDJ on Wed Dec 18, 2019 2:58 pm

For information, I have seen lots of MQ that have been lifted with springs and shocks where the ABS sensor harness and flexible rear brake hoses are now too short, and when even light articulation, or even just hanging the wheels down on a 2 post hoist is enough to stretch the hoses and cause warning lights because the connectors are being pulled apart.

so if yours is lifted or about to be, please mention this to the joint doing it. it could save tears and frustration in the long run
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Re: Result of damaged wheel speed sensor on MQ

Postby lindsay14 on Sun Jan 02, 2022 9:14 am

Also supercheap auto can get the same sensors for around 50$
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