1998 XJ8. ABS and TCS are showing failure right from start up every time. There is no intermittent function. Using a newer Bosch Pro OBD/ABS scanner I got no codes. Cleaned all 4 sensors and checked all the fuses, no change. Since there is no faults and no intermittent operation does that point to the ABS computer/control module? I saw the posts about opening that up and checking pins/solder joints.

 

Before I would start tearing into the ABS I would do some thorough investigations into the condition of the electrics. You don't say whether the indication goes away after running for a little while.
I would check battery voltage after letting the vehicle sit overnight. You should have around 13.5 volts. The vehicle will start with less than 12 but the modules goes bonkers with less than 12 volts.
After taking the overnight voltage I would start the vehicle and recheck the running voltage. It should be around 14.5 while running.
If you didn't have 13.5 or more overnight I would get the battery load tested.
If you don't have 14.5 while running I would recommend cleaning and tightening the battery connections, the engine compartment Bulkhead power connector and finally the ground strap from the right side of the engine to the frame. It is located on the block/transmission joint and runs to the frame about a foot or so behind the right front wheel.

 

Another reason you can get this from startup is the ABS computer under the hood. Its known for loosing contact where the plug plugs into the motherboard. Its actually an easy fix. Unplug the ABScomputer. Its 2 plugs, then take out 4 torq head bolts. I think they are like 4.4 mm. Pull the motherboard off. Then pull the black plastic cover off. Be careful. I just cut mine off with a hot knife. Then you will see 2 big lugs on the bottom of the board. Closer inspection and you will see the positive post has became unsoldered. Just resolder it and reinstall and clear the codes and everything is fine. Have done this on may of these jags. Beats spending 300 for that motherboard There are refurbished ones on ebay for 100 bux but they seem to fault within a few months because of the solder they used.

 

Thanks Vern, I should have added that in searching I saw that bad grounds and low voltage could cause these. Battery voltage was good but I left it on a trickle for 24 hours just to be sure.

The messages/lights are always present. If I turn the key to p1 before start the light is on and never goes away no matter how long I drive the car.

Thanks for the detail on the lugs X2. I'll check those in a bit and report back.

 

Seems your tool is failing to tell you the code(s). Try another.

 

Agreed, I have two tools that gave the same result, which seems to indicate the same operator error...thinking of paying the dealer for a full diag report.

 

Given that the theory of weak soldering points is applicable on your issue, you won't be able to read the codes from the ABS module with a regular OBD scanning tool (e.g. DTC C1095 would be quite typical for that issue).

Only genuine Jaguar diagnostics (IDS/WDS/PDU) will give you full access on all on-board modules and read the codes. There are a few third-party readers (e.g. iCarsoft i930) which can read the ABS-module too, but they are Jaguar-specific models. So I doubt that the Bosch Pro is one of these (at least not for the x308 and x100 series).

So don't draw wrong conclusions from not having any codes - it might be just the wrong tool ;-)

I had that fault on a intermittent basis together with a pending C1095 code and resoldering the connector joints for the ABS pump cured the issue completely.

Follow the links for some more info:
http://www.jagrepair.com/images/Auto...aul%20Bush.pdf
JagRepair.com - Jaguar Repair Information Resource

 

It's easy enough to check the reader- just disconnect one of the wheel sensors and see if you get a code after driving for a few minutes.