I'm a newbie to this forum, longtime member of Miata.net and bimmerfest so I'm looking forward to this one. I just picked up a '01 XJ8. I'd done some general searches for problem issues before I drove 3 hrs to check her out. She was way too clean to let the standard issue TRAC/ASC unavailable warning scare me off. The car was a repo out of Central TX and had been in storage for the last few months. On our first test drive, I noticed a shimmy in the wheel at about 60mph, and the tires looked low so the seller had the tires balanced, rotated and pressure checked and the shimmy ceased. I'm almost positive the warning wasn't there on the first run, but that run was quick due to the shimmy. The TRAC and ACS unavailable both show immediately upon startup and show until cleared. After some onsite review and further follow up I'm almost convinced it's the typical pin failure in the module due to it's immediate and constant showing, although as I didn't notice it until after tire and wheel work, it could be dirty sensors. I've found the recommended photo post on removing, accessing and repairing the module. I'm going to pull the wheels first and make sure sensors are all clean, and I'm comfortable with the pin repair if that isn't it. My primary concern is with the disassembly of the Hydraulic unit. The recommended "best" procedural document clearly shows the unit and step by step processes, but I don't see a drop of Hydraulic Fluid. My question is - isn't that unit under some kind of pressure? There's no mention of replacing fluid or bleeding brake system after reassembly. I've never had to get into an ABS unit before and just want to cover my bases before I tackle it. Also, will pulling the generate a code that needs to be cleared? I've seen that I can get some repaired units for drop in replacement, but that also requires disconnecting the hydraulic lines so I don't see it being much different. Thanks for any hands on info.

 

You dont have the key on when you unhook so you wont generate a code. And you dont undo the hydraulics lines. You unbolt the whole assembly mount and bend the lines just enough to allow access to the module screws and to slide the module out. Then reverse the proceedure once repaired

 

Many have removed the control module without disconnecting the brake lines. The car can be driven without the module but it will not have ABS/TC. Neither do 2 of my cars. The control module does not interface on a hydraulic fluid level. It is only inconveniently located behind the valve body.

 

Thanks for the input. I just ran across a post that may be pointing me in a bit of a different direction. This post provided some insight into the problem related to different warnings. This post was in response to 2000 and newer XK's but indicated that no ABS warning light with messages of ASC and TRAC Failure, pointed to a TPS failure. I've never gotten an ABS warning light, just the messages on the display, and the amber light warning in the speedometer. I'll have to double check but I think I have to start the car before I get the messages. Any thoughts from your end?

 

That TPS (throttle position sensor I assume) thread, if it is the one I am thinking of,hasn't been resolved yet, so be cautious of the diagnostics and information within it being gospel and directly attributable to that scenario. At least until we do find out what the problem is. TPS issues are rarely seen around here.

 

Actually matt tps is a common issue for replacement of the throttle body. But it will put the car in limp home or restrictedperformance. Since that wasnt mentioned i dont believe thats the issue. But you really need to pull the codes to see what the prbolem is as ssen by the abs module. Without those its like trying to shoot a fish in the sea from the shore

 

Bluerdg- not sure where you are in central Texas.. but I have a code scanner if you want to confirm the actual failure code. I'm in Austin.

 

THe common and recurring TPS issue, in my case, is that it still has gold contacts in the TPS and tin contacts in the mating connector - I have not replaced mine with the gold pin replacement kit (available from Jag) as of yet, and about every 8 months or so, especially if it's rainy or humid, I'll get the resettable asc/trac error along with random limp modes... and eventually it will throw the CE light with a P0121 code [TPS circuit range/performance (TPS1 compared to TPS2)]. The dissimilar metals, in conjunction with elevated humidity seem to cause significant corrosion in the interface between pins, causing one of the TPS signals to be corrupted when it reaches the ECU.

Often, just unplugging and replugging the connector will clear the problem, but I use contact cleaner/lubricant from Radio Shack to clean prior to reassembly... seems to last with no issues for, as I said, about 8 months or so.

Could this be your issue? Can't tell for sure, but the TPS connector takes 2 minutes to get to and a minute to clean, so it's an easy thing to try. I'm going to start doing it at each oil change, just to extend that 8 month period out to infinity - or I'll get off my lazy behind and get the gold pin replacement kit.

Good luck!

 

I was wondering about that after reading a few posts relating TPS with the warnings I'm seeing. I bought the car from a wholesale dealer in Ft. Worth with a lot full of Jags, BMW's, Range Rovers and equally impressive vehicles. The engine bay was virtually spotless, but so are the bays on my vehicles after I spend regular time on them. It was obvious after an inspection that the car had been detailed, but to me that has always made problems easier to identify so it doesn't bother me. I saw a crew going over a Saab they had just gotten in and there was very little that didn't see the business end of a light duty pressure washer. I've seen issues of my own with water getting into even o-ringed connectors. I'm going to try a good cleaning of the contacts before I do anything.

 

Ok, I've determinted that the bulb is out behind the ABS warning (don't even see it during the system check). As I'm getting a constant warning without a failsafe warning, I'm being told that more than likely I'm getting the ABS warning, it just isn't showing due to light. With that said, all appears to be pointing toward a circuit failure related to the sensors. I pulled all 4 wheels, but couldn't check the rear leads beyond a short, as they disappear through a grommet into the floor pan under the rear seats. Anyone know where I can find the back end connector, or how I should go about tracking the lead from the module?