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Rear ABS Sensor - Replacement part found.

Listing of rare XJ40 parts and where to find them
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Rear ABS Sensor - Replacement part found.

Postby Hecticat » Sun Sep 22, 2019 9:01 am

Hello all.

As I've promised, I will upload my method of replacing the rear ABS sensor.
EDIT: I have only tried this on a battery in boot car. I assume the sensors are the same on others, but it's no guarantee. my car is a '93.

I managed to destroy the left one completely (twisted the cap off the metal part of the sensor) while changing my rear wheel bearings. A quick search of all the usual portals turned up empty, turns out they aren't available no more, and if they are, they're terribly expensive and/or used. Which I don't like.

Anyway, I did some research, and I found out that the front ABS Sensor of the Renault Twingo up to 2015 nearly has the same dimensions. ABS Sensors are usually hall sensors, and they all work the same. So the only thing you'd need is one to fit the basic dimensions, and the Twingo's does, almost.

Here's the Bosch part number for it: BOSCH 0986594031
And a link to an Ebay listing that's significantly cheaper: https://www.ebay.co.uk/itm/AS4144-AUTLOG-FRONT-ABS-WHEEL-SPEED-SENSOR-I-NEW-OE-REPLACEMENT/264450433757?epid=12021694288&hash=item3d927962dd:g:l-kAAOSwjW5dbE6q

I bought two of these buggers, and checked them against the broken Sensor, and the mounting hole. There are three problems that need to be adressed.

Problem 1: The sensor is too long, by 7mm. The distance between reluctor wheel and sensor is most important for the sensor to work, less than 1mm and you'll get the sensor damaged, more than 1mm and it will not function properly. I measured it and then machined a spacer out of aluminium to go around the sensor. the spacer's size is 7mm, the hole for the ABS sensor is 18mm. You will also need a longer mounting screw.

This can be seen on these photos:
https://cdn.discordapp.com/attachments/ ... 321398.jpg
https://cdn.discordapp.com/attachments/ ... 313892.jpg

Problem 2: The ABS sensor has a different cable alignment than the original Jaguar one. The Jag one has different ones for left and right and has the cable going out of it at an angle, the Twingo one uses a similar one for left and right, and has the cable going out opposite of the mounting hole. There is no "real" solution for this. I fixed one of the rubber cable protectors the twingo sensor had on it so it would be protected against the brake dust shield. It's not perfect, but we have to remember, this is a 30€ sensor that will still be available for decades to come, as Renault uses it in quite a few vehicles. So if it does chafe and get damaged after a few years, just exchange it.

Can be seen on this photo: https://cdn.discordapp.com/attachments/ ... 615094.jpg

Problem 3: The signal cable is too short, and the plug is all wrong. Both the original Jag cable and the Twingo one are coaxial cables, if you can solder them, you can just mate the Twingo cable to the Jaguar cable and be done with it. However, if you can't (Or you're on a tight schedule like I was) you can always take the connector of the original ABS sensor apart at the rear (the Coax cable is seperate there) and then solder a normal cable to the plug, and solder the other part of the cable to the twingo's plug, saving you the bother of having to solder coax cables, which is a royal pain in the ass. It functions normally, and I've seen ABS sensors without coax cables before, so I doubt it will cause any issues. And if it does you can always come back later and do it properly, like I already wrote these sensors are cheap.
Polarity does not matter with hall sensors, they work either way, so it's not necessary to worry about that.

All of this is pretty easy work, can be done cheaply by any half-way competent home mechanic. it solves the problem of the rear ABS sensors breaking and causing nigh-unsolvable issues. It's running great in my jag for 2000km now (stand 22/09/2019)

I hope this helps.
Last edited by Hecticat on Mon Sep 23, 2019 8:02 am, edited 2 times in total.

'93 XJ6 Sov 4.0
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Re: Rear ABS Sensor - Replacement part found.

Postby abercanadian » Sun Sep 22, 2019 4:32 pm

Well done Luke - great solution!

94 XJ40 VDP vin 701729
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230,000 Kilometers 143,000 Miles
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Re: Rear ABS Sensor - Replacement part found.

Postby naki_k » Sat Oct 12, 2019 3:50 am

Good write up. Thanks for sharing.
These sorts of issues are all too common now I think.
Good used parts for the rears are in short supply, as very few people know or care about removing properly.
88 3.6 XJ6 PDH/CEM
90 Range Rover Vogue SE 3.9 V8 LPG
91 4.0 XJ6 Manual
92 4.0 XJR Manual
92 4.0 XJR
93 3.2s - 4.0 Manual conv
93 4.0 Sovereign
93 6.0 XJ81 DD6 x2
93 6.0 XJ81 XJ12
94 4.0 XJR
94 4.0 Daimler
96 4.0 X306 XJR
96 4.0 X300 D6
97 4.0 X300 Sport Manual
2000 LR Discovery ES TD5 A
Breaking 40/ 300