X358 Park Brake fault

[DMG47]

2008 Daimler Super 8. Park brake engages and disengages ok (MOT pass ok) however park brake amber fault light on dash board. Both my general garage & Jag specialist have not come across this issue. No fault codes stored and when reset via OBD light goes out only to reappear once park brake engaged. Both garages suggest replacing park brake motor - this entails dropping the back axel. A lot of hassle for a amber light. Any suggestions?

[PaulGover]

You've filed this under the X350 forum, whereas you probably wanted the X350 Brakes, Hubs and Wheel bearings subforum. I'm not sure if you can get it moved, but people might not notice it here.

I wonder if your problem is that you failed to reset the handbrake after disconnecting the battery. Anyway, it might be worth trying the following:

1. Note your radio reset code
2. Leave the car unlocked (this prevents the siren going off when you reconnect the battery)
3. Disconnect the battery
4. Leave a couple of minutes
5. Reconnect the battery
6. Switch the ignition on,, position 2.
7. With the footbrake depressed firmly but not rediculously so, operate the parking brake lever. This calibrates the parking brake module.
8. Reenter the radio code
9. For extra points, operate each window through it's full range, holding the switch until you hear a quiet click after the window stops moving (this calibrates the "don't chop my fingers off" in the window module).

A known problem with the parking brake motor is damaged wiring, but that results in fault codes.

[DMG47]

Many thanks - however the fault appeared during normal use not after battery disconnect. My garages have tried as you suggested (normal practice) but to no avail.

[ptjs1]

Thread moved to appropriate area.

Paul

[iRS]

It is possible to replace the EPB motor without dropping the axle. Its not easy though. Was this not in a recent magzine?
I would haave thought recalibrating it would fix the probem as Paul descibes.

[PaulGover]

Reading the original item again, I doubt it has anything to do with the EPB motor. If the brakes go on and off, it's fine. If the light is on all the time, there should be a DTC (fault code) stored in the PBM (Parking Brake Module), or the PBM itself is broken, which ought to show up on a decent OBD reader. A first thing to try, if it's not been done already, is unplug and replug every connector in the parking brake circuit to clean the contacts.

"No fault codes stored and when reset via OBD light goes out only to reappear once park brake engaged" makes no sense to me. If there are no fault codes, I'd have thought there was nothing to reset. I believe transient faults can get forgotten by the various ECUs at switch-off, so it may be that there is a DTC, but you need to connect the OBD reader having triggered the warning light before switching off.

My workshop manual says, for the Amber light "Parking brake fault":

• Parkbrake Apply switch circuit failure
• Parkbrake Apply switch circuit short to ground
• Parkbrake Release switch circuit failure
• Parkbrake Release switch circuit short to ground
• Parkbrake Apply and Release switch contacts energized simultaneously
• Parkbrake motor output short to ground
• Parkbrake motor output open circuit
• Parkbrake motor output battery short to ground

with an action of "Check DTCs. Refer to the DTC index for relevant pinpoint test", so it's convinced there should be a fault code stored.

[DMG47]

Thanks all that responded - I will do as suggested and report back.

Dominic