0utlier

90 s4 auto

What am I missing here? Step 3 says the below. I don't see anything that says 13 or 2. I know I'm not doing something right, or looking in the wrong place. Help?

3. Disconnect the connector from the RDK unit, and then place a jumper from pin 13 to 2 on the connector. I used a length of isulated wire that fit the pin holes with some friction. I then used electrical tape to close it, mostly to keep dust and moisture out.

Scott G.

0utlier

Maybe I'm just making this harder than it should be. Going across the top of the plug should I just be counting to find 2 and 13? The below image shows 2 and 13 circled in red if we just count starting from the top left. Is that right?

Ed Scherer

Yup.

0utlier

Thank you. I sometimes tend to make things harder than they should be.

Bill Ball

I am trying to disable RDK in a 91 S4. The light comes on when the car is started and raising tire pressure does not shut it off. So, I decided to bridge 2 to 13, as shown above and do it the stealth way by putting the jumper inside the plug so the plug could still be connected, preserving ABS diagnostics. I opened the plug to find 2-13 already jumped (blue wire), and I confirmed 13 goes to ground and 2 to 13 has continuity. Yet the RDK light is still goes on. If I leave the connector unplugged, the light does not come on.

OK, a bit later here, I read a post from Dave Roberts that says specifically do NOT reconnect the plug to the RDK box after installing the jumper. Other posts from Theo indicate you will lose ABS diagnostics. I guess there is no other good option.

Kevin R.

Actually there may be another way.

Since it is only the message display that's a bother, is it not possible to simply pull wire #8 (BR/GN) from T23 that displays the TPMS warning on the cluster display?

Or will this cause other problems with any part of the RDK or ABS systems?

I would appreciate others thoughts/experience if anyone has done or considered this option.

BTW, if you change out the wheels, the TPMS sensors are in the factory rims correct? I have turbo twist rims installed on MY 1990 and was led to believe that is the reason the message continually pops up every few miles. The system is working. It's just the sensors are missing or disconnected, right?

Bill Ball

Hopefully somebody who knows will comment on your new way to disable the RDK. All I can say is that you are correct about missing sensors triggering the warning.

Crossworth

Can a "properly rated resistor" be connected ...inline.

Will this work a 93 GTS?

c_span

Sorry if I'm being dumb, but I didn't realise there was a potential downside to disabling RDK? (Other than losing tyre pressure monitoring, obviously!)

How does jumpering the RDK affect the ABS? Pretty sure my ABS works as normal and the warning light functions as normal...

Bertrand Daoust

That (ABS diagnostic lost with RDK by-passed) could be the reason why I didn't have any ABS warning with a bad sensor. Hum, interesting!
Thread #8 here:

https://rennlist.com/forums/928-foru...off-fixed.html

Does anybody ever have an ABS warning with the RDK by-passed?

Kevin R.

This is more about an RDK that "is" working where the warning message is what we want disabled.

To me, that is much simpler than disabling the whole RDK system.

I found that there are TWO wires leading to the instrument cluster. I believe one is for the RDK warning icon and other for the RDK digital warning message.

Perhaps both wires should be removed from connector T23:

#8 (BR/GN) = Tire Pressure
#14 (BL/YE) = RDK-Tire Pressure Control

At least that is how reads on Sheet 4--MY 1990 "instrument Cluster and Senders" schematic page.

Now has anyone done this with any success? Are there any implications to this system or any other systems if these two wires are pulled from T23?

borland

I have the RDK jumper between 2 and 13 on my '90 S4. RDK disabled and no ABS fault codes.

Using Theo's diagnostic tester to enable the Digital Cluster's Diagnostics and examining the switches for both ABS and RDK....

the cluster's display indicates that 'ABS is not OK' and RDK 'Is Installed'. Here's the page from the Porsche Diagnostic manual...

Kevin R.

Okay, well so much for my idea. At least it was worth a go to see what would transpire.

Here is what happened when I used the Porsche electrical tool kit to remove pins from connector T23.

#8 (BR/GN) = Tire Pressure (SUCCESS = NO RDK ICON)
#14 (BL/YE) = RDK-Tire Pressure Control (New Message = "TIRE PRESSURE CONTROL OFF")

The RDK computer is programmed to recognize if a wire is cut or missing and does not like it. So, that means, the BRIDGE method recommended above.

Apparently, according to the previous post, there should be no ABS faults. I would want to ensure that just because there are no faults that would mean the ABS system is still functioning normally.

borland

From the owner's manual, what you describe is the "system fault" warning messages. The other possible message is a graphic pointing to a specific wheel with low pressure.



The jumper between pin 2 and 13 of the RDK controller connector is the same electrically as grounding pin 7 of T23.

Learning how the RDK controller communicates to the cluster would be a way to configure it so it thinks the RDK is not installed. Ideally, you would want to configure the cluster as if it were a car that came from the factory without RDK.

The '89 model came with digital dash and ABS, but no RDK. I haven't compared the '89 wiring with the '90, but it could be that the ABS controller is different between the two years.

Kevin R.

Okay, that's good to see the system fault from the owner's manual to describe what I was getting.

Grounding pin 7 of T23 another option? And no jumper available to place at this juncture.

Yes, it would be good to know about MY 1990 if ABS functions normally when this bridge is in place between pin 2 and 13 of the RDK controller plug.

I want the display gone with ABS still working normally for 1990.