Brett928S2

Hi All

My rear wiper used to do 3 wipes then park on left side of screen...

Nowdays it does 3 or 4 ish wipes and parks anywhere on screen

Anyone any idea how the parking mechanism works ??

All the best Brett

928 S2 AUTO V8 4.7 LTR 1986 IRIS METALLIC BLUE WITH X-PIPES ,RMB ,PROMAX CHIPS,
KICKDOWN SWITCH - K&N FILTER - WIZARDS OF NOS - NITROUS KIT 150 HP - 505 HP/500 FT LBS TORQUE -
PCGB UK 928 FORUM MODERATOR - Email managingdirector@pchealthcare.co.uk

jpitman2

One traditional method : wipers are switched on by earthing a permanently live supply to the motor; when the switch is turned off, there is a secondary earth made via a wiped track inside the motor case (on the back of the worm wheel), which is broken where the park should occur. In your case, if this is how its done, the extra earth seems to have failed, or the wiped contact is worn out or corroded or ? I have seen it done other ways, like stopping the motor with +12V on both sides, but I dont know how the 928 does it - check the wiring diags, look for a damaged earth lead near the motor connector.
jp 83 Euro S AT 50k.

Brett928S2

Hi

Thanks for the general advice

Someone must know how the 928 one works though ?????????????

All the best Brett

Mrmerlin

check the connections at the hach area for the wiper motor, also check to see if the relay next to the hatch release is connected, properly , sometimes this connection or relay can come loose,also check the grounds

Brett928S2

Hi

Done all that....all looks perfect....just cannot figure out how the park works....whether it is in the relay or in the motor mechanism itself ??

All the best Brett

Mrmerlin

park mech is in the motor, open the relay next to the hatch mechanisim and see if it looks burned on the contacts

daveo90s4

Brett, not sure about all 928s, but on my 1990 S4 there are two fuses that relate to the rear wiper - one makes it go and one makes it park in the correct position. On my 1990 S4 the horn is on the same fuse. When my wiper doesn't park properly and the horn doesn't work, I simply put in a new fuse (must be a short somewhere but I can't be bothered fixing it). Maybe in your case its just the wiper parking fuse that has blown? Try the horn!!

Brett928S2

Hi Dave

Just checked...horn is working ,so not that

All the best Brett

jpitman2

Its inside the motor.....
jp

Jim M.

The momentary switch energizes the control inside the rear wiper relay (mounted next to the wiper motor). This energizes the relay contacts, which turns on the rear wiper. After about two or three seconds, the rear wiper relay turns off, removing the power that it furnishes to the motor. There is a separate power supply directly to the rear wiper motor thru fuse #18. Inside the wiper motor, there is another set of contacts, operated by the wiper drive mechanism. These contacts connect the separate power supply to the wiper motor. The contacts are closed except when the wiper drive mechanism is in the park position, so if the wiper is away from the park position when the relay cuts off, the internal contacts furnish power to run the motor until the wiper gets to the park position. Then the internal contacts open, and the wiper stops. Windshield Wipers don't "park" only run. Try replacing the intermittent wiper relay. Cleaned up all my problems, which duplicate your description.

Jim Mayzurk
93 GTS 5-spd (now with rear wiper delete)

PorKen

You can replace the fancy 3 second rear wiper relay with a plain ol' horn relay, and it will wipe once, and park.

aguk928

There is also a mechanical reason for the rear wiper not parking. It is work checking if the arm on the wiper motor mechanism is pushing down and springing back up freely also the slot in that arm wears with time and does not mate/hold properly with the wiper arm mechanism on the hatch itself, that can lead to the wiper not parking also.

mitche

how do I connect this "plain ol' horn relay" is it some kind of standard?

I dont understand the orginal relay, thus the problem of replacing with another one...advice, please

mike
-84 928s
paying rennlist member from today

Alan

The rear wiper delay relay is interchangeable with a standard Bosch type SPST or SPDT relay - you can get them almost anywhere - pull out the old one plug in the new one. Ideally buy one with a mounting flange so you can screw it into place - the stock one has a mounting bracket on the side.

Functionally the delay wiper simply stays on on for about 2-3 seconds after it is triggered by the coil - so a quick press of the wiper button gets you 2-3 wipes. Some people (incl. Ken) think this is annoying - since if you want 3 wipes you just hold the button.

The relay has nothing to do with the motor parking mechanism - which as other have said is totally integrated into the motor. Either the motor or the seperate fuse (horn) for parking is supect if parking stops working - (motor stops in mid-cycle).

Alan

Ninespub

Whack the wiper!

Paul Barrera
'91 $4 with a whacked wing!