ferrari0266

Hello,

I have a 1990 928 S4 that my dad purchased brand new when I was still in middle school. My dad rarely drives it because the road is bumpy in my country (Taiwan).




The car runs pretty strong but it has some small problems.

First, the dash lights go dim when I turn on the headlights. I dont know if its the ground.
Sorry about music,forgot to turn it off when I film.

Second, how do you turn off the tirepressure sensor? I think the sensor is removed. According to the mechanic that work on the car, Taiwan is too dusty so it clogs the sensor. Is there a way to bypass the thing? so the ECU thinks the sensor is still working.


I have never work on a Porsche before so pictures will definitely help.

Thank you.

WallyP

The dash lights dim by design - they would be too bright at night if they did not dim. The brightness can be adjusted with the roller **** on the right side of the instrument panel.

The RDK (tire pressure warning system) controller is a black box on the side of the car by your left knee. Unplug the wire harness from the box and leave it disconnected. Put a jumper connection between pins 2 and 13 of the harness connector - this will disable the warning system. Keep the control box in case someone wants to restore the car someday.

ferrari0266

Thanks for the answer WallyP. Do you happen to have a picture of that RDK plug?
Thank you

WallyP

https://rennlist.com/forums/928-foru...to-repair.html

ferrari0266

Will I still be able to plug it back on with that jumper on it?

Seems like RDK is also responsible for ABS sensor. I assume the ABS sensor will be useless once bypass the RDK?

Thank you

993turbo

Does NOT involve the ABS at all. No worries.

TheoJ

hi,
the dash dimmer (potentiometer) is on the left side since the 1989 model came with the digital instrument cluster. And the instrument cluster has an internal ambient light sensor that automatically corrects the brightness besides the manual dimmer.
The RDK is completely insensitive for dust. Who told you that? There are other reasons to get rid of the RDK ecu, and also reasons to keep it. If your wheels have RDK sensors you might want to find out if you can cure the problem. If they don't... you need to make the instrukent cluster think that the RDK is there and ok.
The RDK also uses the ABS sensors for information, so yes there is a relationship, but the ABS works without the RDK, so no worries.
Just disconnect the RDK and "fool" the instrument cluster. Here is a link to some info:
http://jenniskens.livedsl.nl/Technic...6/MyTip618.htm
Check out my website for more info on RDK and dash.
regards

ferrari0266

I dont think the mechanic know much about Porsche's RDK.
I will check the tire pressure tomorrow and make sure its set to spec. Seems like I need to get the tire pressure above 40psi?
https://rennlist.com/forums/928-foru...king-help.html

rbrtmchl

It's not just a matter of setting the right pressure level in the tires. I saved the following from another post in RL:

Procedure...

Air front tires to 30 psi rear to 38.
Drive around the block not exceeding 15 mph
Air the fronts up to 42 rears to 50.
Drive around the block not exceeding 15 mph.
Bleed fronts down to 36, rears to 44.
You are done.

However, I agree with the other recommendations. Disable the RDK using the jumper as described.

rbrtmchl

Here is the actual Porsche procedure for calibrating the RDK to eliminate the warning lights.

ferrari0266

I tried disconnecting my RDK today and it will not come out or move at all.
Is there a special way to disconnect it?
I believe this is the RDK.

rbrtmchl

Looks right - under the dash, above where your knees would be in the driver's seat, correct? If I recall correctly there are two fasteners holding it in position. Remove the two fasteners, disconnect the connector, and proceed with the bridge as described above to defeat the warnings (good decision by the way).

This link shows what each of the electronic control units looks like - very useful.

http://jenniskens.livedsl.nl/Technic...0/MyTip021.htm