# P32 Parking brake



## zaskar (Jun 6, 2005)

Could somebody please advise re an intermitant fault on the parking brake.

Vehicle.
1999 Georgieboy Landau 3301.
P32 chassis 6.5 TD

Vehicle has electro/hydraulic parking brake mounted halfway down chassis on passenger side.
When moving shifter from PARK to DRIVE or REVERSE, the hydraulic pump can be heard to whine as it spins up and releases the parking brake.
However, this doesn't always happen, there is just silence from the pump.
On the bottom of the stearing column is a plunger switch operated by a cable from the shifter. I've noticed that if I "jiggle" the cable a bit, it seems to cure the fault and the pump will operate.
Is this coincidence or could it be wear/corrosion/bad contacts in the switch?
The pump reservoir is full and in the past, I've fitted a new green pressure switch on the side of the pump which had failed and up until now it's been OK.
Has anyone had to replace this switch?
If so, what sort of a job is it because I cant see how to disconect the operating cable from the switch.
Also. I p[resume that the 2 wires coming off the switch (1 black, 1 green - I think) go directly to the pump mounted on the chassis or are there any other relays/switches I should check?
Thanks


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## olley (May 1, 2005)

Hi Zasker just got this of the net:

I just recently had the Auto Park Brake fail on my Holiday Rambler and with a chassis manual, a little troubleshooting and $47.38 I fixed it myself. The system is really quite simple. It has a hydraulic pump that pumps the system up to 1800psi to overcome a spring in the actuator and disengage the parking brake when the ign switch is on and shift lever is not in park. This pressure is maintained by a solenoid valve until the unit is put back in park. At that time, the pressure is relieved and the actuator spring takes over and engages the parking brake again. The most common problem is the pressure maintenance switch which is located on the front bottom of the hydraulic pump.
It will leak and let the pressure drop.
So, if the auto park brake light stay on and the pump cycles, this switch will, most likely, be the culprit. Switch PN 15961566 available from most any GM dealer because it also works on 1 ton trucks. 

Sounds like thats your problem.

Olley


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## zaskar (Jun 6, 2005)

olley said:


> Hi Zasker just got this of the net:
> 
> Olley


I'm aware of that problem but as I said, the pump just doesn't spin and when it does eventually spin the system and it's pressure are fine.
I'm convinced that the pump is ok, it's something electrical before the pump that's dodgy

Thanks anyway


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## olley (May 1, 2005)

Hi Zaskar I have the WCC chassis guide which covers all P30-32 and W series, Its a 35meg download so I doubt I can get it to you.
There is a section on the auto brake including a schematic as below.
If you like I will copy it to cd and post it to you.

Olley


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## zaskar (Jun 6, 2005)

If you like I will copy it to cd and post it to you.

Olley[/quote]

You Sir, are a gentleman. Cheers mate. PM on the way.


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