At 01:45 PM 9/27/02, tommy penngotti wrote:
>hello all...I have DR's directions about disconnecting the RDK (tire pressure system) but would like a little advice on the "jumper wire" have any of you guys done this trick ..easy? Where do I get a jumper wire & is it all one piece or does it need connectors?? help there...also, can u use the RDK system on new tire/wheels...just cranked up a notch & picked up some 17's to replace my 16 stock wheels...thanks!

Starting in 1989, Porsche added a tire pressure monitoring system, called PDK. It was not a popular system, and was discontinued a few years later. The system was overly sensitive, and most people didn't want to add the (expensive) sensors to aftermarket wheels. In order to get rid of the constant warnings, it is common to disconnect the system.

The RDK unit is below/under the dashboard on the drivers side, above the clutch pedal (or where it would be on autos). You don't have to remove any access panels or the dash to get at it. The part number on the unit is 928 618 150 01 (or 00).

Disconnect the battery ground strap before starting the bypass procedure.
This is for safety and will also clear any RDK faults while you are doing the bypass.

Disconnect the connector from the RDK unit, and then place a jumper from pin 13 to 2 on the connector. You can use stranded insulated wire to make the jumper - no connectors needed if you get the right size wire to be a snug fit in the connector. Tape up the connector to hold the jumper in place and keep the connector clean. You can also open up the connector and put the jumper inside the connector.

Use some plastic wire ties to secure the connector back up under the dash,

DO NOT try to plug the connector back in the RDK control unit. The Control Unit can also be removed very easily if desired by removing the 2 Phillips-head mounting screws.

Wally Plumley
928 Specialists


I finally got around to disabling my tire pressure warning (RDK) controller on my 1990 S4. This is a simple matter of removing the RDK controller unit, and in its place installing a jumper wire between pins 2 and 13 of the RDK wiring harness connector (see the shop manual for pin number identification). The controller is easily accessible and just above the driver's footwell.

However, I did check the drain current across this jumper and the current was measured at 20 mA. That's 20 mA with the ignition key removed. Not bad, but I thought 5 mA would be better, so instead of the simple jumper wire, I jumpered the terminals with a 1.5K ohm resister.

A mystery to me, is how someone discovered this wire jumper trick. My quick review of the GTS wiring diagram, found no such jumper. The GTS came without RDK, but uses the same instrument cluster as the 1989 and later models, so there should be a jumper some where. Maybe someone can explain this?

90' S4, Slate Metallic



it is strange I know. I would almost believe they changed the software in the 1994 instrument cluster. Btw: the RDK was omitted somewhere in MY 1993 and the GTS was sold already in 1992 (US a bit later but that is irrelevant).

1989/1990 model:

Ok, the RDK sends a signal to the instrument cluster via pin #2 on the RDK. That connects to connector 23 pin# 14, and goes from there to the instrument cluster Pin #6. Putting the signal on ground makes the RDK alarm disable. Apparently the instrument cluster has sort of a pull-up input that makes it 12v when not connected.

 The pin #13 is the chassis ground to pull the signal to ground and flag it as "all ok" for the instrument computer.


1992/1993 model:

same story. No difference. Apparently the RDK was still existing which seems not correct as it was omitted in 1993.....


1994 model:

now it gets interesting.  Pin #6 on the instrument cluster is not used anymore. On connector 21 there is no connection on pin #14... and no RDK in the schematic. That makes me believe they changed the cluster or the software version inside the instrument, since the RDK alarm would be always on if no change was made. The last one I know is K29 so there is either a newer version or they changed the hardware.