[h2pmr]

fitted in front of the radiator on the 87-90 model years.

yes i know i know many will have been turned to the open position and the fuse pulled to just keep them open, but Porsche fitted it and i like things like this to work as they should.

so you want yours to work, maybe just bought it and like me want it back to a fully stock 928, hopefully this will help you.

basic basic checks first.
is the motor plugged in?
is the actuator link rod still on?
should be as below:

20240922_101715.jpg

20240922_101754.jpg

if link rod not on, check that the flaps can be moved, maybe they are seized up or have been tie wrapped open.
if no link rod on, see my thread on here on how to make one before you go any further, as they are NLA


next, with a cold engine, bonnet open, ignition off, the flaps should be at100% open as below:

20240922_101839.jpg

20240922_101901.jpg

next turn the ignition full on but don't start the car, the flaps should be fully tight shut or at 0% as Porsche say
turn ignition off and they should go back to 100% open, if yes, just need to check the 30% operation, post number 3 below

more to follow

[h2pmr]

so the flaps stay 100% open, when the ignition is turned on.
unplug the motor connector, pictured above and check for 12v on the female pin 5 of the connector and an earth on the female pin 6.
the pin numbers can be seen inside the connector
if no 12v check the fuse number
if you have 12v and an earth, disconnect the link actuator rod and give the motor a 12v feed and earth as pictured black earth red 12v,.

20240922_104027.jpg

the motor should just keep going around, if not the motor is dead
the motor only turns with 12v on male pin 5 and earth on male pin 6 NOT the other way around

next we go to the WSM and check the full operation

[h2pmr]

WSM pages 19-11 to 19-26 are pretty good but not perfect, if you do not have the WSM the main checking page is pictured below

20240922_111237.jpg

these checks are carried out on the control unit - situated under the trim on the P/S sill with the tailgate pull knob on it -connectors.
the control unit has 2 connectors, connector I is the top one and connector II is the bottom one
checks are carried out on the connectors with them unplugged and ignition off

20240922_111303.jpg

see above
starting with the 30% test, so if the flaps are at 0% or 100% the flaps should at least move
get a length of wire approx 6" long and bare both ends, put one end of the wire into the female pin number 7 of plug I and the other end of the wire into female pin number 2 of plug II, FOR APPROX 2 SECONDS then remove the wire

you should hear the faint click of a relay when you do this, if not you will need to check the relay is fitted / working

the flaps should now be at 30% open, better to check looking down from under the bonnet and the flaps should be approx 10-15mm open.

more to follow later
cheers
Phil

[h2pmr]

next onto the 0% position, fully closed, do as below

20240922_111311.jpg

and finally the 100% fully open, instructions in the WSM below does not say which connector pin 1 is in.
but pin 7 and pin 1 are both in connector I

20240922_111323.jpg

of note:
when the flaps are 100% open the main shaft the rod is connected to is very close to the power steering cooling pipe, make sure this pipe is not bent and is fully clipped down in position.

when fitting a motor and you have no idea what position it is in, plug it in and turn the ignition on and off and it will set itself to the correct 100% open position, after the final ignition off

the other pages in the WSM give other checks to do but hopefully these basic checks will help someone, some day

and if anybody can confirm, which side of the car the flap control unit is on, on a LHD car + the flap motor fuse number that would be great.
and let me know if anything is incorrect, as those that don't make mistakes, don't do anything

cheers
Phil

[h2pmr]

and finally, when i was cleaning and testing a set of flaps to sell on ebay, i noticed the lower flap pivot was not holding in position, so gently drilled a 5mm hole all the way through and fitted an M5 nut and bolt to hold it all together, works like a charm.
NOTE, DO NOT TIGHTEN THE NUT, this is a pivot point, so as pictured use a nyloc nut, to stop the nut coming off and only tighten untill the nut/bolt just touches the sides of the plastic, so it can pivot freely.

would be possible to do the top one the same, but would need a very shallow head on the bolt, as you will see when the flaps are fully closed.

might put some black paint on the nut/bolt to hide its newness.
now for a warm
cheers
Phil

20240922_130958.jpg

20240922_131005.jpg

[h2pmr]

fitted another motor i have to test its operation and wondered why the rod would not fit on when it was fully closed.
the alloy has broken where the ball should fit and someone has done a pretty good repair to it, the ball is rock solid in the alloy.
it would just needs the rod shortening and it would all work as intended
cheers
Phil

20241006_194026.jpg

20241006_194058.jpg