Hi,
I had an ABS/TRAC error in my 2001 XKR for monthes. I decided to solve the problem by soldering the electronic module 2 monthes ago.

Bad idea !!! I got new errors and problems ABS/TRAC + "low brake fluid level" + "unkonow component" messages + Gearbox was out and restreint mode on!!
I bought a new module and made it checked by ecu.de workshop. Situation improved but still have ABS/TRAC - Low brake fluid level and unknow component messages.

That's the situation, now....
They are still on, even the ABS module is disconnected from its multiplug.
I checked ABS sensor impedance from the multiplug : all four around 1 kohm. Brake liquid level is OK.
I checked the ABS multiplug and connection with ABS electronic module.
I cannot check error codes : no one of my electronic tools (iCarsoft, 930, Mangoose and ELM plug) can connect to the car.

Errors are still on whenever the ABS module is connected or not. Does that mean that it is still faulty (even it has been changed and checked)? Or do I have to check others parts like ECU, etc, etc???

 

To my knowledge, the ABS module houses one of the 2 terminating resistors for the proper operation of the CAN bus. If this module is disconnected, CAN will not work and no scan tool will help. There is documentation out there about debugging CAN. I believe it starts by measuring resistance and that it reads close to 60 Ohms. You will also need power to the diagnostics plug (check the fuse). Double check the connectors for bent pins, etc. Jagrepair.com has the electrical diagrams.

Best of luck, keep us posted.

 

As you’ve had the ABS module new and checked, I would go check on:

1. ECM ground (as you can’t get the OBD2 connection)
2. Both battery cable terminals, (negative and positive), both ends (the positive connection to High Power Fuse junction box is known to work loose in the fuse box)

 

There have been issues even with 'new modules' (e.g. madhatter). However, the first line of defense is to look at the whole CAN bus (the electronics connecting ABS, ECM, TCM and the Instrument Panel). You need the ABS module connected to the system. As noted above by fmertz, if the module is not connected, the electronics do not work. The ODBII connector is under the left side of the dash near the bonnet latch. Looks like this



From CAN Network Integrity Check without WDS

– With the ignition switched OFF, connect a voltmeter between pin 6 (CAN high [+]) and pin 14 (CAN low [-]).
A reading of around 60 Ω indicates a good CAN bus:

< 60 Ω indicates a short circuit on the bus

> 60 Ω indicates high resistance on the bus (e.g. around 120 means that the ABS module is likely not electrically connected to the rest of the bus)

– Disconnect the Voltmeter from the DLC and switch to the voltage scale.

– Switch the ignition ON to position II.

– Connect the DVOM between DLC pin 6 (CAN high [+]) and ground. The measured value should be 2.7 V

– Connect the DVOM between DLC pin 14 (CAN low [-]) and ground. The measured value should be 2.5 V

 

Grounds and connections have been tested by my local Jaguar. He's far better than me for that!!! Nothing looked wrong...



Impedance between 6 and 14 : 61.3

Voltage
6 to GND : 2.64
14 to GND : 2.31

Looks good???
Are there some value to take on the ABS module???

 

This is GREAT stuff, and I will need it. Can't get my obd to work on the 2003xkr... Thank you all.

 

Great. So next step would be to determine what the codes are with one of your OBD tools, but they will not communicate, or do they not give you any codes for the ABS (different things)? If it's the former, that's odd since the bus appears to be physically intact and, for example, INST (and by extension ECM) knows that there is a ABS/TRAC error. So, it is probably a good inference that the CANbus is working, at least to some extent. You could put an oscilloscope on it to see if the signals are being transmitted across the bus, but it seems like a waste of time since other things likely wouldn't work if the bus was degraded.

If it wasn't for your tools not communicating, I'd strongly suspect the ABS module. Recently MadHatter had a rebuilt module that was broadcasting the wrong heartbeat code. There is a code broadcast several times a second to tell the other modules that ABS still exists. If the number is not decimal 14 for the XK8, there is an error. He had no OBDII codes, but INST knows that the ABS is not appropriate for the XK8. Do you know anyone else with a different OBDII reader around you so you could at least get some idea what the system thinks the problem is? Did the dealer have the same problem?

 

For now, only my iCarsoft 930 looks working.
Errors are P1637, P1720 for engine.
U2500 for ABS (CAN error bus FROM ABS).
It matches with an ABS module problem even if it has been professionally rebuilt.

I think about trying a third ABS module, just to check...

 

I hate to chime in when I don't have exact answers (which is most of the time)... But, my experience with ABS problems, usually created by my "fixing" things, is that when I have a serious or semi serious ABS fault, due to the way systems are integrated in the abs and CAN systems (systems that I'm just learning more about) there can be an expected cascade effect where other faults and systems related to the faulty component(s) trigger others. I've had abs problems (one brake not being sufficiently bleed for instance and a bad connection to the sensor) throw an ABS light which caused *intermittent* restricted performance, gear box faults and other things... It was terrible, I was on the highway. As soon as I got the new from caliper (the old one had a sheared off bleeder valve) and bled the system, everything came back online, righted itself.

It seems 1637 and 1720 are connected to the braking system. 1720 is speed sensor,,, at the wheel. The 1637, I think, is the abs module itself. Somewhere in there a mistake (prolly one you made) is making things funky... I would get in there and recheck and double check much to do with the breaking system. It really doesn't take much to make these cars go haywire...

Once I got to the point I felt everything is kinda as it should be (really noting the "new" abs module was the correct part - or even working) I would do a hard reset to reintroduce the abs module to the car from scratch. Also,,, could your codes be residual codes where a clear codes OBD command would clear them out?

 

Yes, I'd see if I could find a known good ABS module. U2500 says that there is a failure to communicate somewhere for some time, either ABS or ECM. P1637 says that the CAN heartbeat is missing for the ABS, either because the ABS is not sending or ECM is not receiving. P1720 is loss of speed signal, either ABS failure to send or TCM failure to receive.

All of these point to ABS module failure or ABS module circuit failure, at least intermittently (since the static electrical measurements were good). If you reset the codes, how quickly does the ABS/TRAC come back?

 

That's an interesting point : I currently have a problem with my calipers bleeding (switched for Brembo ones at the same time I tried to have the ABS module repaired).

I checked each ABS wheel sensors impedance from the ABS pins connector : around 1 kokm for each one. Even it looks good, do you think there can be another problem on these sensors??? I have two all new sensors in case of...

I'm currently trying to get a known good ABS module to be sure of this part of the CAN.
Even resetting codes, ABS/TRAC message stays on the board.

 

Bleed.those.brakes.right!!!

Air in the line, one brake, two brakes, 3 brakes throwing mixed pressures in the lines/pumps/reservoirs at the abs module and internals (I think) will cause all kinds of havoc... What I'm kinda learning is that things that seem so simple it couldn't be causing all of the problems I am experiencing,,,, can cause all of the problems I'm experiencing, lol... These cars are a real trip!

 

Are the bleed nipples pointed UP on all of your calipers...? Air bubbles rise... I have heard of people installing calipers upside down,,, accidentally...

 

Okay, probably not intermittent.

I'd focus on the module rather than the brakes. For example, the brakes do not cause a U2500 or a P1637, but the module can cause the P1720. The P1637 points right at the module given everything else. Once the module is right as rain, then see if there are other problems.

 

I would listen to CRBass!
Lol,,, also make sure the brakes ain't on upside down. **** happens, haha

And,,, keep it light. It's gunna be alright!

 

Bleed nipples are UP!!
I will look for another module (the third...) to check this part of the problem.Whatever the problem is, I would need to bleed the brakes due to persitent airbubbles inside...

 

Note that you likely do not need to install the 3rd module in place just to check function (so no bleeding necessary unless you currently have air in the lines, if so, I'd advise against driving the car before bleeding...). Just disconnect the connector and connect to the new module. The CAN should function. If U2500 and P1637 go away, then you've made progress and can decide to install the module.

 

FWIW, check the Instrument Cluster TSBs on jagrepair.com as there can be failed solder joints that cause CAN errors. There is a VIN range to help but take it with a grain of salt. The IC acts as a bridge between various bus technologies and need to be fully functional. Does not hurt to check.

 

Along these lines. jeje, what is the model year of your car?

As a short story, my MY 2001 had had the INST fix from the TSB on manufacture (2001 vin 18534), but at least two of the joints on the INST connector looked like crap (and all of the joints on the gear illumination module and several on the ABS module. The gear illumination module connector appeared to have been soldered by a toddler after consuming an energy drink.). Don't know whether that fixed anything since I systematically resoldered every joint from ABS to the INST through the gear illumination module trying to find my intermittent problem that ended up being the ECM rebooting at random times. Different codes, however, pointed at the ECM in that case (U2500, P1637, P1797 among others).

Conflicted moral of this story: Yin: I now trust the codes as the first step. Taken together they suggested the ECM wasn't transmitting for a time, which was what happened when I happened to have a CAN bus reader on the car when it happened. Yours taken together suggests your ABS module is not working properly. Yang: Not trusting the codes completely, I learned a vast amount about the CAN bus for the XK8 which has been vastly helpful for me subsequently. And, bonus, I fixed the gear illumination module joints (and replaced the gear illumination module bulbs), which would surely have been another random problem in the future.

 

FOR YOUR Bloody Bleeding pleasure,,, I just read this in another post about brakes... What jumped OUT to me was 2bleed valves per caliper... New to me,,, but I'm a new xkr with Brembo owner... Thought it might help


The standard OEM brake calipers on the XK8 use a JLM2192 superseded by new part number MDJ7478AA. The are listed as M8 X 1.25 X 35mm long. These measurements were confirmed by actual measuring and also a Jag parts site with actual picture and diagram with a scale plus printed measurement. Ordered Speed Bleeders part number SB8125LL (H9428) that are same size, but 39mm long. 4mm should not present a obstacle. Not installed, but appears they will work in place of the standard Bleed Nipples.

The Performance Brakes (BREMBO) appear to use a M10 X 1.0 X unknown length. Each side of caliper has a Bleed nipple so require 2 per caliper or 8 per car. Hopefully someone has a Brembo caliper and will provide the length and confirm the correct thread pitch and size. OEM part number appears to JLM21319.