Hi Guys-

I thought I searched for this but couldnt find it and my apologies if it has already been discussed before but I have determined that there is an issue with my left hand rear speed sensor. Measuring the resistance At the abs control module I am getting minimal resisitance which tells me its either faulty wiring or a fault or dirty speed sensor. Could someone guide through the removal process so that I may clean/test the rear speed sensor? It looks like I need to remove the wheel and basically unscrew the speed sensor? What do I use for this?

Regards,

Scott

 

I know your car seems unique to you, but there are over 21 years of XJS' floating around.

If you want to save time in the future, add a brief description to your signature now so you won't have to read this response in the future. Model year and engine would be ideal. If you put this off for later, I guarantee you'll see this response again in the future.

 

I updated my profile...its a 96 V12 Cabriolet. I got the tire off and now trying to figure out how to test the speed sensor...How do I get thewire off?

Thanks in advance

 

twopumpchump,

You haven't got a 96 V12 cabriolet. There is no such thing. I'm guessing that you've either got an 86 V12 cabriolet or a 96-registered V12 convertible. (It won't be made in 1996, but it might be a 96 model year car.)

If you've got a 96-registered V12 convertible, it's easy to get to the rear ABS sensor. It's held in place by a small bolt on the top of the hub. The bolt is about 10mm or so. Just undo the bolt and remove the sensor.

I'd really suggest that you buy the Jaguar Parts and Service manual on DVD. I wouldn't even considering running one of our cars without the manual.

Good luck

Paul

 

The front speed sensors on my 96 XJS (I have the AJ16) were 4mm bolts I believe...yes, they were tiny. I had to set the socket by feel, it wasn't easy. (I keep thinking perhaps they were 6mm, but I swear I remember them being 4mm)

If you have a 96 XJS with the 6.0 v12, you might have something special. (That's why I was hoping you would add your engine)

I'll wait for a clarification on your car since a late model has some additional info you might need on where to unplug the sensor. Apparently (according to my manual) it is unplugged from inside the car?!?!

Get back to us on what you're driving so we can help.

 

It won't be an 86 if it's got ABS sensors.

 

The wire is integrated into the speed sensor and is not removable. The connector is under the rear seat and the wire is rather long as it makes its way to the hub. So be sure to remove the rear seat and check the resistance at the connector there. The wire does not come off at the sensor. If you have no resistance it's most likely a break in the wire at some point. The sensor is very expensive and you may be able to effect a repair if you're handy. Remove and inspect, often the break can be seen. If not then cut the wire back 6 inches or so close to the sensor and measure the resistance. If its good you can simply cut off the connector end and replace the wire in between. Be sure to solder, tape and heat shrink your connections. You have to use shielded wire or use a twisted pair to prevent electromagnetic interference. Jag used shielded wire but twisted pair is just as effective in this application.

If you have outboard brakes you most likely 1993 to 1996.

As for the year... Since the OP is from NY it could be a Canadian model, late production, a mis-read or just a simple typo. As far as I know... XJS' were produced until April of 1996.

 

I have the production data from JDHT somewhere but as I recall there were no V12 coupes or convertibles sold in North America in the 1996 MY?

Anyway on late model XJS, in order to remove the sensor you must remove the back seat cushion. There is a connector tied to the drive tunnel. Disconnect it and pull the sensor out from the wheel well.

I would carefully check this connector for signs of dirt or corrosion. It's quite possible that water has made it's way to the connector over the years and is now causing a problem.

 

Also you mention that you have minimal resistance, could you tell us what you measured? The specified resistance of the sensor coils is 1100Ω +/- 50% so anything between 550Ω and 1650Ω is in spec.

You should have 2.5v dc on the pins at rest. Then a 2.5v ac voltage with frequency varying with wheel speed. (100Hz at 10mph, 200Hz at 20mph etc.)

 

I have a confession...I don't own an XJS. The car I am working on is a '97 DB7 which was based on the XJS platform and shares many of the same parts (not to mention, these days looks pretty similar to a Jag!). The speed sensors installed on the car are in fact late Jaguar XJS. I have the DB7 factory manual which is OK but just doesn't provide the detail I am looking for and quite frankly most of the guys on the Aston Martin forum don't work on their cars so can't provide much guidance which is why I turned to you guys. Basically the impedance as measured from the abs module is around 6 ohms which effectively means a short circuit somewhere. At this stage I want to measure the impedance at the speed sensor and from what you guys are telling me I can do that by removing the rear seat and if I get proper impedance looking at the speed sensor then the problem is a short somewhere in the wire connecting the abs module to the speed sensor. Conversely, measuring the impedance looking from rear seat to the module would probably yield me close to 0 if this were in fact the problem. One last question...The path of the wire from the ABS module to the speed sensor connector...After the rear seat does what path does it follow to the engine bay?

 

There should be a hole with a rubber grommet that the wire passes through.

All in all, it should be a pretty long run of wire because the connector should be inside the car.

You didn't need to hold back. We are more than willing to share information with any of the Jaguar brethren. Next time you'll want to claim having a 1995 XJS, if you want to lay claim to the V12. As you may already know, the XJS was only offered with the 4.0 in 1996 and I believe they were all convertibles. (I think there may have been 4 coupes, but how rare would that be?!?)

 

So the truth comes out... Lol.

I know the 6 cylinder db7 is pretty much all jag except for the body panels and the interior. They did upgrade/beef up the components on the v12 version. Like they added additional gussets on the rear suspension pieces and put larger brembo disc/calipers. Probably one of the cheapest to run Astons you can buy, with the most amount of DYI knowledge available online from the jag guys.

I would recommend getting a xjs parts manual and Repair Opetation Manual (ROM). As almost all of the mechanical bits are the same and a good chunk of the engine.

 

My car is actually a bit of a hybrid as far as you guys are concerned since although it was based on the XJS platform my engine is from an AJ6.

Thank you!

Scott

 

You didn't swap the engine out, did you? There should be an AJ16 under the hood.

I've seen the interior of your car. You guys use the same parts to adjust the seat/lumbar/seat heater. It's that door mounted cluster, right?

 

My understanding it has a beefed up 3.2 aj6 with an eaton supercharger not an aj16 as that didn't come out until the next year.

 

Wow, I did not know that. It does use a supercharged AJ6. I just always assumed it would have gotten the AJ16 engine that the XJR got.

The XJR is quite a bargain when you put it up against the Aston...

 

The DB7 is always a reminder to me of what could have been for Jaguar.

The car started life as a concept in the early 80's as the XJ41 & 42 convertible and coupe. It was planned to replace the XJ-S in around 1985-86 and be called the F-Type and was based on the XJ40 platform

Lack of funds kept pushing back the intro and in 89 Ford bought Jaguar and immediately killed the F-type. Tom Walkinshaw had done a lot of work on the car and thought that it could be done at a reasonable price using the XJ-S platform. So on his own volition he had a young designer called Ian Callum go see what he could do After producing the new concept, Jaguar said thanks but no thanks, so Walkinshaw asked Callum if he thought he could turn it into an Aston Martin!! And so in 1994 the DB7 was born.

And to close the circle of irony, finally in 1997 the XK8 was born and of course Callum eventually became head of design for Jaguar.

Funny how life goes

 

I believe when Ford NIX the XJ-S replacement they turned it over to Aston Martin who was in need of a replacement model for the earlier DB. To look at a DB7 engine bay I would swear it was an AJ16 in 3.2L with lower compression. Beautiful car, if funds were available when I bought my XJS that would have been my 2 choice, right behind the XK8 coupe in the 2000 to 2003 my.

 

The engine is an AJ6 with an Eaton supercharger.

 

OK so I got the rear seat off and see the speed sensor wire coming through the grommet and it goes into the center tunnel. How far into the tunnel to I have to go to the end of the speed sensor wire to pull it apart and measure resistence?