I have a problem with the electric parking brake on my Jaguar XK X150 (4.2 V8, built in 2008).

Symptom:

Error message for the parking brake in the vehicle (yellow immediately after ignition, red warning message after driving off)

EPB can no longer be activated

According to the repair shop, only one side of the brake is still responding.

Battery resets (disconnecting) and recharging have not improved the situation.
The battery has also been replaced with a new one. Still no changes.

Diagnosis with SDD:

C1785-00 (PBM) – Output, electric parking brake motor – Interruption

C1799 (PBM) – Hall sensor – Circuit failure

The EPB actuator was already replaced about 2 years ago with a new actuator (part C2C40572).

Are you aware of any follow-up problems after replacing the actuator (e.g., cable break, connector, internal Hall sensor)?

Are there any known weak points in the wiring harness between the PBM and the actuator on the XK X150?

Have you had any cases where only one side responded?

Is it realistic that the actuator is defective again, or should we look more towards the cable/connector/mechanics on the rear axle?

 

Unfortunately, I’m still having the problem: when applying the brake, the EPB actuator ‘rattles’, then a fault message appears; the handbrake can also be released for one time again, also with rattling. The EPB cannot applied again unless battery reconnect.

I tried a lot of things and I'll give a run down:

• Bought the car in November – the EPB worked fine. According to the paperwork, the actuator had been replaced with a new one two years earlier. I regularly parked on a slope; the EPB worked without any problems.
• About a month later, the error appeared for the first time.
• First, I bought a new battery. No success; same error.
• Diagnosis at an independent Jaguar workshop:
  • Fault codes:
  • C1785-00 (PBM) – Output, electric parking brake motor – Interruption
  • C1799 (PBM) – Hall sensor – Circuit failure.
  • Rough visual inspection of cables and cable assembly carried out there: everything in order
• Visit to a garage (non Jaguar specialists)
  • a used EPB actuator unit was connected on a trial basis (via the plug only, without the cable): same fault pattern.
  • The mechanics there felt that the tension of the cable on the old installed actuator was too weak. They were able to increase the tension of the cable. Now, when applying the brake, you can at least hear a short hum of the motor, until it starts to rattle during the process and throws up an error message again.
• The EPB module was opened, checked, cleaned; it looks very good.

Questions:

1. Could it be that this isn’t an electrical problem, but a mechanical one? Does the EPB need to be recalibrated? As far as I know, the EPB recalibrates itself after every reset, also tried various procedures (5 times braking etc.).
2. Or would it make sense to buy a second-hand EPB module to rule out this potential fault as well?

Unfortunately, I don’t have an SDD system here to diagnose the faults or to calibrate anything.

VIDEO
Here is a video after reconnecting the battery and trying to apply the EPB (0:06) and releasing the EPB (0:18)
https://imgur.com/a/golKt4h

 

You have a gear motor with hall effect sensor that counts the number of revolutions between latch and unlatch.

The audio sounds like a mechanical problem: pinion jumping teeth on the larger/ring gear.
That seems to be a secondary problem following the re-tensioning of the cables.
I would have thought that the controller would cut out when maximum torque was reached, before damage to the motor/gears.

There is a possibility that the controller program is corrupted. It is easy to reprogram with SDD, then check.

The original problem was likely the controller missing the Hall sensor pulses. Possibly/unlikely the controller or connector. Unlikely the wire harness.
However, the gears are jumping. That could still be the controller causing excessive torque. Use a clamp-on DC ammeter (that uses Hall effect) to check the maximum amp draw.
If not excessive amps, no excuse for gears slipping, replace the actuator. Then, re-check the actuator maximum amp draw.
If still excessive amps, change the controller.

It should be possible to operate/monitor the actuator using SDD.
If you are not doing the work yourself, a Jaguar specialist with SDD will pay for himself in the long run.

Keep us posted on how you resolve this issue.