To All,

A strange issue has popped up. Fuses are not blown!

my 96 xjs with the Bosch abs system is demonstrating an issue with the abs warning illuminating after reaching a speed of ~20mph.

this happened a few years ago but went away on its own….(I attributed this to moisture)

Prior to installing new ball joints my abs light kept going on ……so while replacing the ball joints I decided to clean the all the speed sensors.

Did not resolve the issue!

There does not seem to be an issue with the overall system as I can slam the brakes on at 40mph with no hands on steering wheel and the car stays straight and no tire squeal.

I have heard of an issue with the abs control module (mounted to the abs pump) where two (2) pin locations on the board have sketchy solder joints?

what about things like the control relay (mounted) drivers side rear trunk. Or the abs speed control unit also in the rear well.

What else could cause this issue?

Where else should I look for bad grounds.

I would like to resolve this issue before it goes up for sale. I know that I stated about a year ago that I would sell my cat…..but my heart wouldn’t cooperate……I liked this thing too much!

after doing the ball joints I now know it’s time.

any comments regarding the market place site. Any luck selling cars.

As always thanks for your help!


Softball60/Paul

 

Every time my 95 6.0 and 96 4.0 sit for a few days, the ABS light will come on for the first drive. So far, they have always reset themselves without problem. Design problem or actual problem somewhere - I don't know but I don't let it bother me.

 

Same here on my '96 xjs 4.0. I think it's a wiring or sensor problem. When a module problem, the warning light does not go out after starting.

 

I'm afraid without pulling the ABS codes, we'd all be taking stabs in the dark. Cleaning the sensors was the best thing you could have done. All that is left is throwing (expensive) parts around....or performing the (free) ABS module repair.

I would see if I could find an OBD2 reader capable of pulling jaguar specific ABS codes.

 

Thanks for the replies.

Vee, were you referring to the solder joints in the abs module mounted under the abs pump? If so, have you already tried yourself? If the solder joints are bad, is that the reason the light only comes on @~20mph but the system seems to be working?

I think tomorrow I will measure resistance through the connectors and get some readings.

Does anyone know what the resistance should read approximately?


Thanks

Softball60#/Paul

thanks

 

I did do that...but that was before I was able to read the codes. My issue ended up being a failing speed sensor. I bit the bullet and paid the $550 for a new one and never had a problem since.

I don't believe that is your problem since the failing wheel speed sensor would work for awhile after being cleaned. Initially it would work for months, then weeks. It's basically a magnet, so it always attracted dirt.

While your brakes may work, the ABS might not. You would only be able to test that with a hard stop on gravel?

Wheel Speed Sensors vary by speed. 2.5V at 10MPH; 100Hz at 20 MPH; 200Hz at 20MPH. Not sure how to bench test that.

The Wheel Speed Sensor ground should see 2.5V at rest.

Download the electrical diagrams from www.jagrepair.com

 

Clean not only the sensor but also the sensor ring. Rust formation on the sensor ring can also prevent the sensor from functioning properly.

 

From what I've seen, all these speed sensors from this era are falling apart. ie the rubber that coats the coax that they're made from is deteriorating and exposing the coax cable to road salt etc. the coax then deteriorates to the point you now have an open connection. The simplest way to determine if its the speed sensors, is to just take an ohm meter and measure it right from the pins on the ABS module. you can do all four in a minute, they (as I recall) should be around 1.2k. Download the electrical pdf and find the correct pins.

 

I have a 1996 that is not garaged and I daily drive it in the Washington DC area. The wheel speed sensors have a very thick and durable insulation on it. I've seen no such degradation on mine. The one that I replaced certainly looked healthy.

Now perhaps the 1994 uses a different sensor?

 

I suppose that is possible. Jag may have reformulated the rubber at some point as I've never seen automotive cable deteriorate like this...I've looked on ebay too at used sensors, and they all seem to have this deterioration at some level. (at least for my model year)

 

My 96 has a Bosch abs system not sure about the 94. The cables look to be in excellent shape.

I checked the front two (2) sensors that have a connector interface located in the engine compartment, right and left fender well.

Checked both sides of the connector. I read ~ 2.5V Input to sensors for both and ~ 1400 ohm resistance to sensors for both……So I’m guessing they look okay

On the back I cannot locate an interface connector that allows me to check both input volt and resistance of sensor.

It looks as though the cables for the back run all the way from abs control module either of the rear wheels.

Could the relay be causing the light to go on at 20mph if it’s going or gone bad or would the light be on the moment ignition is turned on and stays?

Thanks

Softball60/Paul

 

The ABS system does some kind of internal diagnostic that either turns off the stored code, if the fault has gone away, or I suppose, the opposite. I think 15mph is the usual threshold.

If you could get your hands on some device that can read the Jaguar specific ABS code, you will know precisely what is creating the fault. If you do a search on the forums, I think others have shared devices that can read these codes that can be readily purchased.

 

Anyone out there have a code reader that can diagnose a 1996 xjs abs issue.

let me know the brand.

Thanks

Softball60/paul

 

Obviously the BEST diagnostics for your car would be WDS. WDS was what we got at the dealer in 1998 (with Windows 98) to replace PDU.

IDS replaced WDS in 2006 and was almost the same except a faster machine and later software (Windows XP) and will work on Jaguars with OBDII.(same with WDS)

 

Is there a brand name associated with what you reference


Thanks

Softball60/paul

 

From Jaguar, hard to find. Most are broken or lost. Some specialists still have one.

 

Let’s try this another way!

To check the front it was relatively easy just undo the connector located on side of the fender well.

I could not locate the connectors for the rear sensors…? I thought they were in the rear seat compartment..but could not locate.

any idea were the rear connectors are located.

Thanks

Softball60/paul

 

Can you just follow the cable from the sensor up to where it enters the body? and then follow it from there in the inside?

 

I have …. Didn’t see any connectors in the rear wheel compartments….thought it might be under rear seats because I can see where each rear wheel cable enters rear. I didn’t see any connectors there either.

Can’t imagine that the cable runs all the way up into engine compartment without any connecting point between rear sensor and abs control module located under abs pump motor.

Thanks

Softball60/paul

 

I think the connectors are under the rear seats. I have seen them there on pre facelifts.