voltage regulator

[Yoni_d]

Hi Guys,

I was wondering if there is some sort of voltage regulator for the instrument cluster that ensures that it will always receive a constant voltage?
If so, few questions:
1. What is the voltage that should be within the instrument cluster? is 12V or perhaps 9V?
2. If there is a voltage regulator - where can I find it?

Thanks!

[kelanel]

voltage regulator is located directly in the alternator, the instrument cluster just has an exciter circuit behind the voltmeter that helps the alternator start to charge. Note that the voltmeters are well known for being innaccurate due to multiple reasons. multimeter at the jump post while running is the best way to tell true voltage.

[Yoni_d]

Thanks!
But the reason I was asking this is not because I see a wrong reading of the voltmeter but because my coolant temperature indicator displays different reading when the engine is running and when I just open the switch to 2nd position (just after shutting down the engine)
I also see the temperature indicator going up when I turn on the head light or activating any other electric device.

This is why I thought that there should be a special voltage regulator just for cluster panel.

[Fixer]

Yoni D, I have the same symptom with my instrument cluster.

It is always the same problem,

In the morning when cool and or cold outside temps, all gauges work fine,

then as i drive for 20 minutes and the cabin warms up the volts gauge just drops and the temp gauge starts to climb and pins to hot.

But the motor is just fine and not hot at all, i check. Volt are almost 14, The idiot lights light with key and go out as they should when started.

If the car sits in the warm sun and the motor is cold and i start it, the problem is there, no volt gauge and temp gauge pins to the top. Happens every time this way.

The next morning in the cool garage when i start the car everything works as it should.

The malfunction occurs when the cabin is warm only. I figured it was an expansion of the printed circuit/contact issue.

Odd.

[Fixer]

Lifetime Rennlist member Lizard 928 recommends the following:

rerun all solder joints in the central warning brain under the dead pedal (to the left of the clutch pedal).

You have a number of bad solder joints in it.

[Yoni_d]

This problem really drives me nuts - I can understand your feeling.
I did noticed that if insert my hand under the cluster panel and touch the big connections of the cluster panel then the indicators starts to jump a bit...
From one point of view it does looks like connections problems but I thought that there must be some voltage regulator just for such cases...
I noticed that that a ground point for the cluster panel instruments is the MPIV point. What is the location of that point?

[harborman]

Originally Posted by Yoni_d

This problem really drives me nuts - I can understand your feeling.
I did noticed that if insert my hand under the cluster panel and touch the big connections of the cluster panel then the indicators starts to jump a bit...
From one point of view it does looks like connections problems but I thought that there must be some voltage regulator just for such cases...
I noticed that that a ground point for the cluster panel instruments is the MPIV point. What is the location of that point?

I would clean every ground connection you can find, clean all fuses and holders. Make sure you replace the braided ground strap from the battery to body. It may look fine but it could be corroded inside the connections. Clean your battery connections. With engine off, your battery should read about 12.56 volts, 13.8 with engine running.
Also clean the ground lead from the engine block to body.

[Yoni_d]

Ok, thanks I will do that and report back - hopefully in a few days.

[Fixer]

I just removed my instrument cluster, it is clearly labeled 12V.

[harborman]

Originally Posted by Yoni_d

Ok, thanks I will do that and report back - hopefully in a few days.

You can buy a new braided ground strap for about $42. I recently had to replace mine. The old one looked fine but had corroded badly inside the crimp on the wing nut side.

[lfausty]

does kinda make u wonder when a gauge works at all, haha is it reaaaally working.

hmm waaahah oooh temp gauge then your coolant change , crankcase venting, exhaust blocking, whats starting to cause heat that's not cooling it back down, bong bong bonkers bong bong dead bong ....

[Guest765]

Originally Posted by harborman

You can buy a new braided ground strap for about $42. I recently had to replace mine. The old one looked fine but had corroded badly inside the crimp on the wing nut side.

I know the Porsche tax etc etc but that's ****ing outrageous for a foot of wire and two crimp ends. Go to home depot or Lowes and buy two feet of heavy gauge braided wire for about seven bucks, and get a set of crimp on connectors to match the battery and wing nut. Total cost less than $20.

[harborman]

Originally Posted by fwayfarer

I know the Porsche tax etc etc but that's ****ing outrageous for a foot of wire and two crimp ends. Go to home depot or Lowes and buy two feet of heavy gauge braided wire for about seven bucks, and get a set of crimp on connectors to match the battery and wing nut. Total cost less than $20.

You can I guess. I think Porsche wants $72 but the one I bought looks exactly the same and has the correct end to go under the wing nut. Worth it in my book unless one is satisfied with a muckety mucked up solution. To me $20 ($42 + shipping) more is not a problem for an exact replacement.

[Opelotus]

Poor connections creating excessive voltage drops throughout the gauge cluster cause all sorts of wacky issues. Even after rewiring my cluster the coolant temp and fuel gauges move a tiny bit when turning the headlights on and off. Most annoying is the voltmeter will bounce from 14v to 12v every time the green arrow indicator for the turn signals lights up.

[Fixer]

Investigating my issue yesterday, i noted that the shop that maintained my car for decades removed an aftermarket alarm and reconnected leads to the connectors at the central warning box. They had to add 2 inch pieces of wire to reconnect where the alarm co ha to tie in. They soldered the ends of these repairs, i think they create more resistance and that creates a problem.

[Yoni_d]

If the instrument cluster is labeled 12V it means that if the voltage is higher it may affect the reading?
I guess I will start to dig into this thing until I figure it out.

[Fixer]

Yoni, the only voltage regulator is on the alternator itself. There are many connections though to check between the 'jump post' and your instrument pod which could affect voltage and/or be a drain. I need to do the same.
Start by making sure your car is charging by testing under the hood to see if you are making 13.5V when the car is running.
If you are making more than 14V your regulator is going bad and you should replace. good luck.
Matt

[Fixer]

Yoni, clean the ground in front of the rear passenger taillight. It can be done without removing the rear quarter trim if you remove the 2 sheet metal screws at rear of trim and gently bend it out of your way. I also removed the luggage loop which was in the way.
Anyway moisture gets back there and after cleaning mine (which were oxidized pretty bad) it corrected the problem.

[Yoni_d]

Originally Posted by The Fixer

Yoni, clean the ground in front of the rear passenger taillight. It can be done without removing the rear quarter trim if you remove the 2 sheet metal screws at rear of trim and gently bend it out of your way. I also removed the luggage loop which was in the way.
Anyway moisture gets back there and after cleaning mine (which were oxidized pretty bad) it corrected the problem.

Thanks for the tip! If its not a big effort, can you please take a picture of those 2 bolts or just of that area?

[Fixer]

You also want to clean the grounds above your fuse block, you have to remove the wooden cover plate (I love that we have Porsches old enough to still use wood in manufacturing after you remove the wooden swinging fuse block cover plate, the cluster of ground wires will be behind another electrical device.

I don't think i can take a pic of the ground wires in front of the rear right side taillight, but if you open the hatch look at the right rear corner of the interior trim, you will see sheet metal screws. remove them and the luggage hook and flex the trim back. The ground wires are bolted to the body just ahead of the taillight. Color of ground wires is brown. Use the appropriate grd sandpaper to clean all contacts, re secure the10mm bolt, and coat with dielectric tune up grease to seal it up from moisture.
Do this to the ground wires above fuses also.
It corrected my issue