Hello everyone, I have a problem with my 2007 XK X150. The brake fluid level warning light and the brake light are flashing, and there are no error codes. I checked continuity in the brake fluid reservoir, and it's fine. I also checked continuity on the wires going down to the ABS module at pins 6 and 7, and they're good, so the wires are fine. My question is, what could be causing this? Could it be a faulty ABS module ECU? Thanks to everyone for your help.And sorry for my English, as I'm speaking from Spain

 

Whenever you have an electrical glitch, the first thing to do is make sure that your battery is fully charged. Use a digital voltmeter in the morning, after your car has sat overnight and before you start the engine. If it's less than 12.6 volts, recharge it with a 10 Amp or greater battery charger (not a trickle charger or battery maintainer). If it doesn't hold a charge, replace it. Make sure the replacement battery is fully charged before you install it because many batteries sit on dealers' shelves for months discharging.

If it's not your daily driver, I recommend you use a quality battery maintainer. I use CTEK brand maintainers and recommended them. Search this Forum for how to install it, there are several ways to do it. IMPORTANT: 5.OL Owners - Just remember to NEVER attach anything to the negative battery terminal - that's the one with the Battery Monitor System module. Always use a chassis ground. 4.2L engines don't have the BMS module, so you can attach the negative pigtail to the negative battery terminal if you want to. I prefer using the remote battery terminals in the trunk and alligator clips. Quick and easy and I've never had a problem.

See: https://www.jaguarforums.com/forum/x...lay-ups-73471/

Stuart

 

Hi, thanks for replying Stuart S, but I don't think the problem is the battery since it's only two weeks old, a new Varta 100Ah 830 Cranking Amps battery.

 

Well, to refresh the topic, nobody knows anything, it didn't happen to anyone else. I know it happened to the XK100 and some pins inside the ABS module were soldered on.

 

Sorry you're not getting a response. I've never heard of the problem. USA market here - this is all I see in the service manual. And you're saying you've physically confirmed continuity @ the ABS between pins 6 and 7? I assume you disconnected them from the ABS while checking?

3. Brake Warning Indicator

This warning indicator is displayed in a red or amber color (dependant on market) as a brake symbol

in all markets except USA which have the word 'BRAKE' in addition to the symbol. The indicator is

controlled by high speed CAN messages from the ABS module and the parking brake control module.

The indicator is illuminated in a red color for a 3 second indicator check when the ignition is switched

on.The ABS module monitors the fluid level in the brake fluid reservoir using a level switch. If the fluid

level falls to below a determined level, the switch contact is broken and the ABS module detects the

low fluid level condition. The ABS module issues a CAN message which is received by the instrument

cluster which illuminates the warning indicator and displays the message 'BRAKE FLUID LOW' in the

message center. The warning indicator can also be illuminated by the ABS module if an Electronic

Brake Distribution (EBD) fault is detected.

I'll do some more digging.

 

Related, to earlier comments too, the EPB is one of the first components to complain should your electrical source not read 12.5v+.
@Sean W , thanks for making me look that up! I didn't realize the ABS module was affected by low fluid, though it certainly makes good sense.
Unlike the EPB on the LR, the one on the xkr is original and works like a charm. As for the ABS module, I haven't had or heard of issues with it on the XKR either. Sounding like a misstep by the abs module. Codes?

 

@guy yeah he mentioned no codes thrown.

 

Thanks for replying, everyone. The brake fluid level is at the maximum. I checked the continuity by disconnecting the wiring harness that goes to the ABS ECU, specifically pins 6 and 7, and it shows a signal. If I unplug the brake fluid reservoir sensor, there's no signal and it doesn't throw any ABS codes. The brake light comes on red because the brake fluid level is low. I'll try to provide a video. The fault is intermittent; it comes and goes.
Well, I don't know how to send the video or the photos 🤦

 

No need for the video. You disconnected at the ABS and have continuity. Have to tried disconnecting on both ends to confirm continuity in the wiring itself? Perhaps a break in the wire since it's intermittent. Otherwise, I agree you're pointing to a short/open circuit in the ABS

 

As I mentioned before, I checked the brake fluid reservoir sensor, which has two pins, one black and one blue wire. The reservoir showed continuity. Then there are those two wires that go to the ABS ECU harness, which, if I'm not mistaken, is a 36-pin Ate brand harness. Those two wires correspond to pins 6 and 7 of the harness. Once I unplugged the harness, I checked the blue and black wires and they showed continuity, but if I unplugged the connector from the brake fluid reservoir, there was no continuity. That's why I suspect the fault is in the ECU, not the wires. I'm not sure if I've explained myself well. 😅

 

I think we're saying the same thing. I was suggesting disconnecting @ both ends and test continuity of the blue wire end to end, then separately the black wire end to end to ensure no break in the either wire. If you confident of the wires and the actual switch inside the reservoir isn't faulty, then yes you're only left with the ABS module. Others would have to weigh in on its repairability. I'm not qualified to answer that part.

 

Bueno, gracias, es una gran idea. No había pensado en comprobar la continuidad de cada cable. Lo comprobaré mañana y te aviso los resultados. Gracias de nuevo. Saludos cordiales.

 

Hi Sean W, well, as you mentioned, I have a permanent continuity between the blue and black wires. I think it's clear the ECU is messed up because I don't know what else to buy 🤷‍♂️

 

I vaguely remember something about dirty wheel sensors on my xk8 and yes I also read that whole saga about resoldering the ABS. I think it mentioned a couple of places where you could get the unit refurbished

 

Hi Alanroberts50, I don't think it has anything to do with the wheel sensors, because if it were the sensors, they would have caused a fault. Besides, the sensors were checked during a road test and all of them were working correctly.Thanks, regards.

 

Hello again, and thanks to everyone who was able to shed some light on this. In the end, I decided to buy a complete ABS module with the ECU, using the same part number as mine. But I have a question: does the ECU need to be reprogrammed? Does anyone have any ideas?