I've read a number of posts concerning the Parkbrake Fault message and yellow light on the dash, but none apply to my odd situation. My car is a 2008 XJ8 Vanden Plas.

My Electronic Park Brake works just fine. I can manually engage it and disengage it. I hear the motor work and the park brake comes on. It holds the car firmly on a hill. I put it on the hoist and I can see the EBM actuator engage and disengage. It also works fine in automatic mode: when I turn the car off it engages. When I put the transmission in drive or reverse it disengages.

But the yellow light and Parkbrake Fault message still appear on my dash. I've done the reset / calibration procedure by disconnecting the battery, turning the car back on, pressing the brake peddle firmly five times then with the brake pedal held down lightly I've manually engaged and disengaged the park brake (which works fine) - but the warning light does not clear.

When I hook up my code reader the DTC shows c1799. I clear the code, but it comes back on when I restart the engine.

I just want this annoying warning message to go away. Any suggestions?

 

Googled and found this for DTC C1799.

2005 Jaguar XJ Parking Brake TSBs

TSB Number:
JTB-00208
NHTSA Number:
10037272
TSB Date:
June 25, 2014
Date Added to File:
May 17, 2011
Failing Component:
Parking Brake
Summary:
Jaguar: electronic parking brake re-calibration procedure. Updated 10/17/14.

Hope that gets you a little closer to the remedy.

 

Hi frcraig,

The best place to find Jaguar definitions for Diagnostic Trouble Codes is either in the Workshop Manual, which you can download free in six sections from this forum, or in the DTC Summaries manual, which I'm attaching here (2004 is the latest one I have, but it should cover most of the codes for your 2008).

Use Adobe Acrobat Reader's search function (Cntrl+F or Cmd+F) to search for C1799 to see the possible causes. Since high circuit resistance is one possible cause, the first thing I would try is to thoroughly flush the contacts in the EPB actuator's electrical connector with zero-residue electrical contact cleaner, allow the fluid to dry and then reassemble.

The EPB motor appears to be both powered and grounded via the EPB Module, which is grounded at ground stud G24 on the inner right rear wheel well/fender somewhere near the EPB Module and Rear Electronic Module (REM). Remove the nut and wire ring/eyelet terminals, clean them all and the threaded stud with a soft brass brush and electronic cleaner spray. Allow to dry, then reassemble and take great care in tightening the nut. The torque specification is just 6.5 ft. lbs., which is not much more than hand tight. Several members have accidentally snapped off a ground stud by overtightening the nut.

You can download the 2008 X350 Electrical Guide here:

http://www.jagrepair.com/images/Elec...al%20Guide.pdf


Please keep us informed.

Cheers,

Don

 

I couldn't find the TSB Trosty pointed to but here are a couple

 

Thank you for your suggestions. I've cleaned the contacts and earth (ground) points. I even took out the rear seat and checked the connectors that can sometimes become damp on the passenger side from a blocked sun roof drain, but no success. When I use an icarsoft i930 (Jaguar) code reader to clear the c1799 fault it goes away but comes back on the next time the car automatically, or I manually, engage the handbrake. The strange bit is that the handbrake engages and disengages just fine. So I only want the distracting warning and yellow light on the dash to go away! I can't see replacing the actuator (looks like a lot of work) or module if the EBP is actually working fine.

 

frcraig,

A couple of other ideas come to mind.

1. Low battery voltage is often associated with difficult-to-diagnose fault codes, so it would be worth testing your battery, especially under load and while cranking the engine.

2. The C1799 DTC indicates a fault in the EPB motor position sensor circuit: open circuit; short circuit to ground; short circuit to battery voltage; or high resistance.

According to the 2008 Electrical Guide, the wires that connect the EPB Module to the Hall Effect sensor in the motor/actuator housing are Yellow and Yellow with a Black tracer line.

Surprisingly, there are five connectors involved between the Hall Effect sensor in the motor/actuator and the EPB Module:

CR50: 4-way black connector at the EPB Module in the right rear inner wheel well (Yellow wire);

CR32: 12-way grey connector at the EPB Module (Yellow/Black wire);

FP6: 22-way "natural" colored connector on top of the fuel tank toward the right side (both the Yellow and Yellow/Black wires);

CV1: 6-way grey connector at the rear right side of fuel tank (Yellow and the Yellow/Black wires); and

CV7: 6-way black connector at the motor/actuator (Yellow and Yellow/Black wires).

It might be worth cleaning all of those connectors and inspecting the wiring harness (especially near the motor/actuator) for chafed insulation that could be shorting.


Cheers,

Don

 

After cleaning all the contacts (the one nearest the EPB motor above the gas tank was a PITA) I disconnected the battery for a couple of minutes and then went through the reset procedure for the brakes. The amber warning light and the "Parkbrake fault" message returned, but then when I used my code reader to read the code (c1799-hall effect sensor) and then cleared the code, the code no longer returns. Now if I use the code reader to communicate with the EPB module it says "no faults" - but the amber light is still on. After several ignition on/off and battery disconnect/reconnect sequences the light remains on, but the code reader no longer sees any faults or codes. Would I do any harm by disconnecting the battery over night to see if the EPB module or something else in the electrical system is remembering this fault. The electronic park brake is working just fine - in both automatic mode and manually.

 

Hi frcraig,

I'm not sure which amber light is illuminated. Is it one of the warning lamps illustrated on this page of the Owner's Manual?




I can't think of any harm you would do by leaving the battery disconnected overnight. Several of our members have done that. You'll just have to do the EPB reset procedure again.

Since your scanner can read the proprietary Jaguar "C" codes, I assume it can read the "U" codes (Undefined, mostly network-related)? I'm just thinking out loud as to what could cause the amber light when your scanner is not seeing any code.

Don

 

I have C1799 as something a bit different with a list of possible causes from circuit fault, through sensor fault to motor fault.

Can't hurt to leave battery off (need to reset one-touch etc) but I doubt it'll fix anything.

 

Further to Don's question, the amber MIL is the one in the centre (speedometer) ring of the instrument cluster. Directly below it, in the message centre it says "park brake fault". It is not one of the brake lights that come on in the left (tachometer) ring. I've attached a picture. I did some further tests with my scanner and found something interesting. When I run a diagnostic on the rear engine control module I get U1262 SCP J1850 Communication Bus Fault. I also found a stored code UO128 Lost Communication with Park Brake Control Module. Also, when I run a diagnostic on the air suspension module I get C1885 Rear Right Height Sensor Open Circuit / Short Circuit to Ground, and also C1893 Rear Left Height Sensor Open Circuit / Short Circuit to Ground. No warning message. Oddly, just like the Park Brake Fault when the Park Brake works just fine, my rear air suspension works just fine - it is the correct height, smooth ride, and rises and lowers just like the front. I'm thinking the Open Circuit / Short Circuit to Ground Fault for both the Park Brake and the rear Height Senors is common. Their wiring must ground at the same spot, or join through one of the many connectors. In each case there is just enough of an open circuit or short to ground to get an error message or code on running the diagnostic, but not enough to actually cause a problem. Any thoughts?

 

@frcraig https://www.jaguarforums.com/forum/x...-c1893-150514/

I don't know if you have had any water in the rear passenger area lately. I had some thing similar to what you describe which was resultant from a corroded connector under the rear seat passenger side.

Fp6 was the problematic connector in my case.

Prior to replacing the connections, I did air suspension module (behind rear seat), park brake controller, etc. and the new modules dos not resolve issue.

Did a bunch of reading in the electrical guide to determine what the common point is. Fp6 was the cause of my issues.

And the pin out for the connector is documented here:

https://www.jaguarforums.com/forum/x...in-out-150680/

Thanks-
Mag

 

Thank you Mag. I took the rear seat out and found those two connectors. When I took them apart and checked them they looked factory fresh. I did spray them with some contact cleaner and reseated them a few times, but the codes and the Park Brake Fault message persist. I know my local dealer pretty well from previous Jags I've owned that were under warranty. From my experience with them they would want to replace the Park Brake Module and probably the actuator/motor as well, but my guess is that this is an electrical problem and the codes and fault would just reappear.

 

Ok great. Please keep us posted.

I can send you a park brake module if you would like to test; though problem likely somewhere else.

Thanks
Mag

 

Thank-you for the offer Mag. I want to try a couple of other things first before I attempt to swap out the EPB module. I recleaned and reconnected the connectors under the back seat this morning and the Air Suspension rear height sensors fault disappeared, so now just down to the Park Brake Fault light and message. I was exploring some of the additional features of my code reader this morning as well. The DCT for the Park Brake Fault comes up as C1799 Hall Effect Sensor. However I've discovered that when I select Manually Diagnose for the Electric Park Brake module I see three choices 1) read DCTs, 2) clear DCTs, and 3) read live data streams. I hadn't gone into live data streams before. When I did that this morning I see that there are 43 different live data streams that can be read through the EBP module. Each indicates a yes or no and pass or fail value. I have only one failure noted. It reads: electric parking brake failure management mode 7 actuator position fault. I'm wondering if that is what is causing the C1799 DCT and the amber warning light and message? I may put the car up on a hoist and see if I can toy with the actuator 'position' and see if that makes a difference. I'll let you know how I've made out. I also did a comprehensive web search and have found a dozen messages from people with this warning light/message and DCT who have replaced both the actuator and the EPB module with no effect.

 

Hi there, just a thought, you wouldn't by any chance have more issue with this when it's damp / raining / car just been washed etc would you?
I had an issue similar, post about it somewhere, turned out the wiring underside of the car, near the rear diff area was chafed through causing this issue. I had a temp repair done "electrical tape to cover the chafing area" and have had no issues this past year or so.

See #post 24 here....https://www.jaguarforums.com/forum/x...y-x358-113597/

Just a thought and perhaps worth checking?

 

Have you read this post (pictures in post #7) and tried it?
https://www.jaguarforums.com/forum/x...-c1893-150514/

 

Hi there, I know this is an old thread, but I have the exact same situation with my 2005 S-Type. Did you ever resolve it?

 

Hi Mark,

Welcome to the Jaguar Forums! It's great to have you with us.

Unfortunately, frcraig never let us know whether or not the issue was resolved. Have you read all the documentation linked to in this thread, as well as the additional threads linked to?

Also, please visit the New Member Area - Intro a MUST and post a required introduction so we can learn something about you and your Jaguar and give you a proper welcome.

Cheers,

Don

 

Hi.
Thanks for many good tips in different isues.
I had the same problem with yellow warning light «park breake fault» but the park break was funcition.
I got hold of a Jaguar Technical bulletin XJ206-07 and found a wiring integrity problem on the wirer WU(white/blue) infront of CV7-5.
Fixed the integrity problem and the warning sign was gone. :-😀

Just a tip.
Sigmund

 

Hi Sigmund,

Welcome to the Jaguar Forums! It's great to have you with us.

Thank you for posting your success story. That may be very helpful to others.

When you get a chance, please visit the New Member Area - Intro a MUST and post a required introduction so we can learn something about you and your Jaguar and give you a proper welcome.

Cheers,

Don