1992 xj40 speedo not working
Discussion
just bought a 1992 xj40 with a dead speedo. ive swopped the speedo cluster but with no joy. if i press the vcm fault button it comes up with a '68' speed sensor fault.
however, this car doesnt have a speed sensor screwed into the diff (or the provision for), so i guess that it reads the speed of the rear abs sensors (or so ive been told)
any ideas?????
also the diff clonks, if you jack it up and 6&12 the the wheel it makes an audible cluck and i can see the output shaft move about 1/8th inch back and forth. i did grease the ujs which has helped the noise.
i guess this is a diff out job to fix!
ive had a few xj40s, some real dogs, and none have ever had speedo or diff clonk issues
cheers in advance!
however, this car doesnt have a speed sensor screwed into the diff (or the provision for), so i guess that it reads the speed of the rear abs sensors (or so ive been told)
any ideas?????
also the diff clonks, if you jack it up and 6&12 the the wheel it makes an audible cluck and i can see the output shaft move about 1/8th inch back and forth. i did grease the ujs which has helped the noise.
i guess this is a diff out job to fix!
ive had a few xj40s, some real dogs, and none have ever had speedo or diff clonk issues
cheers in advance!
More than the majority of cars with ABS get their speedo reading from a wheel speed sensor.
Does your '92' actually have u-joints or does it have the flexible couplings which are known to wear out?
To check for a gear backlash/pinion bearing problem in the differential, grab the driveshaft close to where it connects to the diff (after the last u-joint) and push it up, pull it down. If you can feel play, there is definitely a problem. You can also set up a dial gauge on it if you suspect a problem but can't feel movement.
I had the rear diff go out on my old Trooper and it was much cheaper to get an entire rear axle from a wrecking yard than to have mine rebuilt. It lasted for about 6 years/60,000 miles before it also died.
Does your '92' actually have u-joints or does it have the flexible couplings which are known to wear out?
To check for a gear backlash/pinion bearing problem in the differential, grab the driveshaft close to where it connects to the diff (after the last u-joint) and push it up, pull it down. If you can feel play, there is definitely a problem. You can also set up a dial gauge on it if you suspect a problem but can't feel movement.
I had the rear diff go out on my old Trooper and it was much cheaper to get an entire rear axle from a wrecking yard than to have mine rebuilt. It lasted for about 6 years/60,000 miles before it also died.
Hi,
You are correct, to be presise the speedo uses the input from the N/S/R wheel ABS sensor, they also had a terible habit of seizing in the alloy rear hub carrier, swelling and causing the sensor to fail, Would expect you to have an ABS warning light up though if the sensors failed completly.
Been quite a while since we have had a 'Forty' in the shop but from memory the speedo signal is outputed from the ABS ECU, remeber changing a fair amount of them.
We probably have a couple of used ones lying about, if your interested send me a PM.
I'd check the sensor out first though.
HTH
Also, if the play is in the outputshaft bearing assembly of the diff (most common) it's an easy fix, will require a press to make it a simple job, takes approx an hour per side and the bearing/seal kits are very cheap now - circa £20.
You are correct, to be presise the speedo uses the input from the N/S/R wheel ABS sensor, they also had a terible habit of seizing in the alloy rear hub carrier, swelling and causing the sensor to fail, Would expect you to have an ABS warning light up though if the sensors failed completly.
Been quite a while since we have had a 'Forty' in the shop but from memory the speedo signal is outputed from the ABS ECU, remeber changing a fair amount of them.
We probably have a couple of used ones lying about, if your interested send me a PM.
I'd check the sensor out first though.
HTH
Also, if the play is in the outputshaft bearing assembly of the diff (most common) it's an easy fix, will require a press to make it a simple job, takes approx an hour per side and the bearing/seal kits are very cheap now - circa £20.
Edited by DTYPE on Tuesday 9th October 21:06
just a quick update
spent all afternoon removing the diff outputs, a little longer than d-types hour a side!!!
the passenger side came apart easy, the drivers side (which i started first) was a swine!, the shaft was stuck in the hub, and took a bit to remove.
the nuts holding the inner hardys on where a bitch to get off, requiring every extension bar i had!!!.
i nearly had a sense of humour failiure when i discovered thet the bolts holding the outputs where impossible to get to, i was at the point of sutting an access slot in the mounting face to get a socket in when i found that it was a simple spacer ring, behind it was the 'real' output that had a pair of nice cut outs in for the purpose of getting a socket on!!!
there doesnt appear to be any play in the bearings, but they sure are grumbley, im gonna press them off and see what they are like.
now here is a question, both sides had 320 thou of shims, is this a set gap, or will i need to reshim them with new bearings, if so, what is the preload??
just got it all to put back together!!!
happy days
spent all afternoon removing the diff outputs, a little longer than d-types hour a side!!!
the passenger side came apart easy, the drivers side (which i started first) was a swine!, the shaft was stuck in the hub, and took a bit to remove.
the nuts holding the inner hardys on where a bitch to get off, requiring every extension bar i had!!!.
i nearly had a sense of humour failiure when i discovered thet the bolts holding the outputs where impossible to get to, i was at the point of sutting an access slot in the mounting face to get a socket in when i found that it was a simple spacer ring, behind it was the 'real' output that had a pair of nice cut outs in for the purpose of getting a socket on!!!
there doesnt appear to be any play in the bearings, but they sure are grumbley, im gonna press them off and see what they are like.
now here is a question, both sides had 320 thou of shims, is this a set gap, or will i need to reshim them with new bearings, if so, what is the preload??
just got it all to put back together!!!
happy days
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