Schocki

Hi guys,
Here is the situation: The oil pressure gauge starts to annoy me a little bit. In the morning it allways works for at least 10 minutes and than it starts to fluctuate around before it dies. When I tap against the instrument pod it comes back to life for a couple of minutes or only seconds sometimes.

I took the instrument cluster out and re-soildered all bad contacts and that solved the problem of an incoorect fuel gauge and non-steady outside temperature indication from the computer. Does anyone have any experience with the internal companents of the oil pressure gauge. It has 3 contacts one ground, one for the light and one for the gauge, correct?
Can I try to remove the plastic holder in the back of the instrument to access the electrical components or should I take it to a shop like Hollywood Speedo?
Any comments welcome

ErnestSw

Hi Michael,
Hopefully Roger will answer your gauge questions. He knows the most about the electronic instruments and has the empty wallet to prove it!
By the way, I've heard that Hollywood Speedo won't touch the Porsche electronic instruments.

ROG100

Hi Michael,
I am sure you have done this already however just in case: -
1) Check all the connections within the four seperate connectors that clip on to the back of the cluster. They sometimes do not make a good connection with the flat connectors on the PCB (printed circuit board). Look carefully at each individual flat connection and you can see a mark where the connectors make contact. Be aware that some do not have a connection - check the wiring diagram to see which is which. If you need a wiring diagram let me know.
2) Where the connection is made from the engine wiring harness to the top of the oil pressure sensor (near the oil filter) sometimes the connection comes loose or a wire breaks (mine did) worth checking.
3) You say you have resoldered bad joints and I assume that was in the PCB. Brave man thats a $1000 part if you can get one.
4) You can take apart the rest of the cluster with no problem and it breaks down to 5 parts. The PCB, the bulb holder, the digital readout, the instrument guages them selves and the perspecs cover.
5) That is about the extent of my knowledge. I had to replace the PCB to resolve my problem and currently Rich Andrade has the faulty unit to try and come up with a repair solution to benifit us all. Porsche told me the PCB board I got was the last one from Germany. Maybe they will manufacture some more if they get enough orders.
6) As for repairing the guages themselves I tried everywhere and no one will touch it (Hollywood, Paloalto and more). However at Wichita Mark Anderson did mention a company that may be able to help and I'm sure if you call him he will tell you. Be very carefull when removing the needle from the guage to access the unit itself as the shaft will break very easily. I decided not to go that route as the guages on their own are $1500. You have to buy the complete cluster the parts are not available seperatly.
7) I have a spare cluster which you are welcome to borrow to trouble shoot your unit.
PM me for more help and I will give you my phone number and email address.
Good luck,
Roger
PS: I assume you have cleaned your earths - sorry grounds.

Schocki

Hi Roger,
Thanks for all the advice let me just tell you what I have done...
1. All the connections have been checked and I checked the connectors too. I hooked up my electronic multimeter directly to the connector for ground and oil pressure and got continous non-intermittent readouts. That means that the wiring is fine :-)
2. I have not visually checked the oil pressure sender but the low oil pressure light never comes on and the multimeter readout is fine. Plus the fact that when I tap on the pod the instrument comes alive tells me that the problem is not in the sender.
3. I worked a lot on electronic parts in my youth and bad joints due to vibration and heat over the years is nearly normal. The CB printed circuits are normally pretty bulletproof unless mechanically abused. The CB VDO uses is a simple single side, single layer circuit and is easy to fix. Look at the internals of a modern laptop and you find a 3 layer CB that is sometimes not repairable if mechanically damaged.
4. I had the cluster itself apart already up to the point where the instruments and the perspecs cover was separated from the rest. If you look at the instruments (oil pressure and fuel tank) from the back it looks like they are held in place by 2 (or3) screws that hold a white plastic mount in place to keep the gauges in place. Roger, if I remove these screws do I have access to the gauges from the back and have you ever looked at the electrical, internal components?
5. Too bad that some parts for the car become rare :-(
6. I called Hollywood Speedo and they told me that they can check the gauge for me no problem. But I think that you are right about the CB and the electronic components. Did any body try to talk to VDO Germany?

Yes, the earths are clean and good to go :-)

ROG100

Hi Michael,
You seem to be about at the point I was, however with your extra experiance with electronics you may be able to go further than I did.
Be very carefull with talking to Hollywood, you need to explain that you have the digital dash as there first response is that they can repair the cluster it is only after you tell them it is digital they catch on.
The reason I did not remove the seperate guage is that I had read a number of posts about removing the needle from the shaft and that this was a hit and miss type of job and easy to break the shaft.
I emailed VDO in Germany and they refered me to a VDO repair shop in Dallas. They would not touch the cluster as they had no way of hooking it up and testing it. You may have better luck calling them and conversing in German.
As you are trying to remove the seperate guage this may be the way to go. I did go as far as undoing the screws and this is where I reached the point of removing the needle and chickened out.
I am really interested in how you get on so as to add to my experiances.

ROG100

Michael,
What was the outcome of your troubleshooting?
Did you fix the problem?
Best,
Roger

Schocki

Roger,
I had no time this week, I got home after night flying at about 1 o'clock each morning. We also flew on Saturday, so there was not a lot of time left.
I fixed my footwell actuator flap today and I posted it on the forum today. I will keep you updated how things go.
The plan of attack is to take the cluster out again and remove the rear plastic mount. Ihope that will expose the internal parts and I can get to the problem. I really don't want to pull off the needle of the instrument because I know that they are really fragile. The problem will be something really small and simple I think because I can convince the gauge to start working as soon as I give it a good tap.
I will keep you informed and will mail you a picture or two.

borland

I've also dug deep inside the digital cluster. The first thing I'd do is replace the ignition switch when you have the Pod removed.

Instead of tapping on the pod, try jiggling your ignition key when the problem reoccurs. Most intermitant problems are related to poor connections of power or ground. Also, look at the schematic and you'll see the instrument cluster gets power and ground from various sources.

Unless you have access to a Bosch Hammer, be careful about test driving the car without the airbag.

Schocki

borland,
Tried your recommendation yesterday with no luck, too bad. I will take the pod off this weekend and I will try to access the internal organs of that gauge. I will keep you posted!

Nicole

When my oil pressure gauge used to "dance" it was caused by a defective oil pressure sensor.

Schocki

Nicole,
I thought that this is the problem too......but.
When I hook up my electronic multimeter I get a good readout and every time I give the pod a light tap it works for a couple of minutes (stable indication) and dies again.