Been a while between drinks folks, mainly because its been pretty smooth sailing in the XJ, But alas the rainbow had to end somewhere.
So the other night i go for a nice slow gentle cruise around town, parked up down the beachfront but no epb activation, hmm thought it may have just been some intermittent glitch so after dinner cruised home and again no epb activation. Thing is the actual epb switch on the gsm module does not seem to operate. There is No icon on driver display to indicate a fault with handbrake unit.
After disconnecting battery and charging with Ctek and hard reset now all i get is a annoying beeping sound while i am driving because i cannot calibrate or therefore activate the epb

List of things i have tried:
Inspect all fuses in manual with epb circuit as listed, under bonnet, passenger and luggage compartment, nothing blown.
Nominal battery engine off, Voltage 12.45v, engine running 14.5v
Run Ctek on AGM cycle, no change
Run Ctek on recon mode, no change
Disconnect battery for reset after another charge cycle, no change.
Remove gsm unit, nothing to really see here all wire plugs in place and firm, and could not dismantle unit anyway. And fixed the annoying dislodged rolling cover over the cup holder using flexible Tarzans grip double sided tape, perfect fix by the way.
Remove rear luggage fusebox, inspect, clean all fuse tabs, relays, inspect circuit board etc and replace, no change
Remove epb module inspect plugs and clean, inspect module circuit board under loupe and light, no hotspots, track damage, expanded caps, dry solder joints etc, clean circuit board reassemble and install, no change
Installed factory tune flashed back onto ecm, still no icon on driver display and no change.

Here's the worst bit, booked into local Jag dealership 4 days later after forwarding all relative info for servicing, i get an email back from the service manager the night before imy booking at 8am in the morning, "we don't service Jags older than 2015 as we don't carry the software to read DTC's from your age of vehicle and yours is supercharged. I recommend you find a high performance outlet to service your vehicle"

From my research i have read NOT to replace the epb module with a used unit, but after inspection, face value it looks fine anyway, but i am not a circuit component analyst.
That's about the extent i can dig into this due to current living circs
Indie says its Auto electricians job, Auto electrician says it a jag specialists job, go figure.

So..... has anyone had their epb fail with no driver display icon lit, and if so where did the component failure lay?
cause at this point i am sick of everyone and raised my concerns with Jaguar Australia about my local dealership response ( by the way Jag Australia was excellent and actually listened)and am ready to just start buying components starting with a new GSM. My next closest dealership is 300km away one way.

 

If you suspect it may be the switch in the GSM then you can test its operation on the bench as the switch is passed through and not actually processed by the module.

The connector on the bottom of the module is marked with a molded '1' in a square for pin 1. Reading left to right, top then bottom row:

pin 10 common
pin 8 apply
pin 19 release

At rest 10-8 and 10-19 are both 605 ohms and 1.2k ohms between 8-19
When activated, 10-8 and 10-19 are both 100 ohms and 700 ohms between 8-19

You can substitute 10 for 6, 8 for 2 and 19 for 14 at the EPB module C4CB01B if that is easier. It is the rightmost grey 24 way one.

If that is switching ok, then really you need to hook it up to SDD for diagnostics before you go swapping modules.

Shocking that your dealer doesn't deal with pre 2015 vehicles (here they are required to carry the diagnostics subscriptions). It is odd though, because afaik even the 2020 built XJs still used SDD - the low build numbers meant it impractical to update to the IP diagnostics. It could be that they just don't want the job.

 

YOU can see why Jaguar sales are struggling with dealers like that !

 

Have you done a visual inspection on the parking brake cable itself?

 

Xdave I thought Jaguar in 2019 went to Pathfinder for diagnostic software?
Can you still use SDD for the 2019 and up cars?
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Cheers @xdave for the electrical info, will bench the gsm today and see where that leads me.

@XJ8JR , unfortunately i cant get under vehicle to inspect due to current living space, i figured if the cables were broken i would get a drivers icon at least and "cannot apply park brake" in message center(seems logical but who knows) i also thought i would at least be able to hear the epb actuator motor run, surely both cables would not snap at the same time? or maybe the actuator is jammed, (similar to Landrover 3 series issue) but again i would have thought a warning light or message center warning would have accompanied this. I will do my best to check the cables anyway.

@Fraser Mitchell , while i do not approve of the dealerships handling of this, i would have at least thought the booking would be kept, even if it was just a visual inspection and to carry out my 68,000km service, and then handed on in person after assistance was exhausted by the dealership, getting the door closed in your face by email the night before your service is booked is appalling customer service.

xdave is right though, maybe they just don't want the work, i can't figure why though, regarding the 2015 thing, i thought it may have to do with the change to Bosch ecm from the Denso system in mine.

lol "ours is not to wonder why, ours is but to do or die, into the valley of epb death rode the X351"

 

@xdave here's the bench test results:
At rest: 10-8 and 10-19, 605 ohms, 8-19,1.2k
Activated: 10-8, 605 ohms, 10-19 100 ohms, 8-19 700 ohms

Question on pin test activated 10-8 is still 605 ohms, does not meet switched quoted resistance of 100 ohms, could this be my problem?

 

I would say that is a good bet as that is used to signal the full extent in the apply direction.

You could try opening it up to see if you can see anything obvious, like a mechanical obstruction. I have not taken a GSM apart as far as exposing the switches, however I have taken the base and knob off before and it is likely just a case of removing the PCB at that point. First you unclip the lower black plastic cover form the sides (it is also the connector, so be careful not to pull it to one side of you can bend the pins). Then there are some hex screws to remove the knob assembly. IIRC there are some smaller hex screws to remove the PCB. If you need to me check, I can do so tomorrow when I am next near to my spare GSM again.

 

i looked at this before when i first removed the GSM but stopped short owing to i had no idea how to remove the shift knob, which seemed to be impeding the module separation into parts to access the switch and allow entire inspection of the circuit board which is part hidden and also secured under the shifter section with a few more of those hex screws, so inspected the visible portion of the pcb under the black cover and reinstalled it.

If you could instruct on the shifter knob removal i should be able to make my way through the rest of disassembly.

Thanks for your help @xdave you are a great credit to the forum.

 

It seems to me that the dealer actions in this matter need bringing to the attention of Jaguar. If a 2015 car can't be examined what hope is there for any Jaguar owner !

 

The centre cap pries off to reveal a single hex screw underneath that releases the knob. I use a piece of 0.10mm shim stock to lift the cap - it is held on with an adhesive ring just back from the outer edge. Once you have it starting to lift you can get your finger nails under it and lift it fairly easily.

If you still struggle with it I'll take some photos showing how I do it.

 

Have completely disassembled the gsm to get to the epb pcb as @xdave suggested.
pretty sure i have found the culprit disabling the entire system.
I had to make some destructive amendments to the switch actuator seen in white in the pics as the steel pins holding the metal switch activator are made only to be fitted not removed.
But before any of that occurred a tiny piece of white plastic fell out of the switch while i was disassembling the gsm, i kept hold of it until i could ascertain where it had come from.

So the Epb switch rocks back and forth, to set and release the epb in the process moving two black plastic pressure pads to complete the circuit to enable activation and release.
One of the white plastic cams that move these black plastic pressure pads had broken from the main white plastic switch stem, thus could not activate the epb circuit, therefore resistance reading of the pins 10-8 when activated showed no change in resistance from 605 ohms to activated 100 ohms.
This, i suspect is also the reason no driver center warning icons are displayed as there is nothing actually electronically wrong with the system, its just not being activated simply due to the broken cam on the main white switch stem.
I am going to try a rudimentary repair to get that infernal parking brake calibration alert out of my ears, retest the circuit and activation and report back with results.

Important : i want to buy a replacement gsm as this epoxy and cyanoacrylate repair i feel will not last, Jaguar quoted me $1200.00 for the part, i was wondering if i buy a new part from the bay, does the gsm need to be programmed to the vehicle? or is it plug n play? i have read people using used parts and them causing further headaches with transmission shifts, not being able to use shift paddles, dsc warnings and the list goes on including epb warnings.

The two black plastic pressure pads for the electronic switch either side which operate from the white cam tabs on central white swich post

Good cam on release side of swich

Broken cam on activation side of swtich

 

Good that you found the culprit. Yes you can just drop in a compatible GSM, however you should reset it using diagnostics and the compatible bit is not straightforward as the earlier ones were revised later in the build cycle to resolve the sticky soft coat finish issues.
Instead what I would suggest doing is finding one with the same finish as yours, and swap the PCB over. That's what I did with mine as a cheaper way to replace my sticky buttons.
Getting the right GSM is tricky if you can't see it in person, but with the label you can look it up.

 

test results after the repair on the epb switch post are completed, all resting and active switch positions on pins are as per @xdave quoted resistance readings in above post.
GSM unit is fully re-assembled and re-installed. Full function returned to EPB, all active driving modes functional and gearshift, no errors or faults on driver display or message center, epb activates and deactivates as smooth and quiet as it should, park brake calibration complete.

Bought a new GSM anyway from the bay, will simply change out the pcb from mine and swap into new GSM module as per xdave's suggestion.

Thanks to the forum and a special thanks to xdave, if you had not posted the resistance readings, this fix would have cost thousands$$$$ to repair as mechanics and dealerships nowadays i feel just change out parts and hope for the best but at your expense, seeing as though it was simply a broken cam on a switch post, very few would have diagnosed that as its not a fault code, and am sure would have had all running in circles at my cost.

So the X351 has come through the valley of EPB death to live another day.

 

Good repair and great pictures!
Another cheap fix compared to a multi hundred dollar bill at the dealer.
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