This is related to an earlier thread regarding what I thought was my car overheating.

It actually appears to be the gauge reading too high due to some electrical issue. . when applying break, temp reading increases, same when turning lights on.

I have a few questions..

Where is the location of the temp sensor?
And any help on isolating this type of problem?

 

Hi .

Try this, Start your car let it warm up look at the gauge while it is running. Then shut the car off, turn the key forward to the acc. pos, read the gauge, If the reading is colder this is closer to the actual reading. this means,It is without a doubt bad ground problem. You need icesharks ground wire kit. Plus the extra ground wire. I had the same problem, His kit is worth the money and fixed problems that I did not even know that I had, like the door chime, and lighting issues.

 

Not only should you clean your grounds, but I've discovered that removing and reinstalling the gage cluster helps as well.

As a case in point all of the gages (with the exception of the temp gage) were reading just a tad low. I did the normal grounds, and the readings improved, but not by much, so I just lived with it.

Recently I had to remove the gage cluster to replace the odometer gear, and when I put the cluster back I noticed that the voltage, oil pressure, and fuel gages were all reading higher and the temp gage was reading lower.

Anyway, the reason the temp gage reads higher with bad grounds is because the meter is wired to read the difference in potential (AKA voltage) across the sender. When you have a bad ground path, the difference in potential goes down (just like if the sensor was "hotter"), so the gage reads high.

The same thing happens when you turn on the turn signals, head lights, fog lights, or any other electrical load, but for a different reason. When you turn stuff on system voltage will drop slightly, but it is enough to affect the gage reading.

 

Think of it this way - ground currents flowing through more-than-zero-impedence grounds will result in ground potentials (voltages) that are different on the two sides of the connection. Flow more current through that connection and you'll get a bigger potential difference between the grounds.

Say, 'S-type, maybe you can tell me how to locate the engine grounds (MP VIII and IX) for cleaning on the 'S'. I can't see them.

 

Location of grounds......

First off, Porsche wiring is prbooaly the worst ever made. The problem is not not usually dirty grounds, it is the wiring itself, especally the part where the connector attaches to the wire. See attached pictures..... My factory ones versus ICESHARKS harnes.

 

On the "S" one ground is in the battery box. The other is on the back of the bell housing. (there is also one more on the front side of the car by the headlights) and tons more all over the car, but there are 2 main battery ones.

 

"First off, Porsche wiring is prbooaly the worst ever made. "

I take it S_TYPE never owned a British sports car. LOL

Lou

 

For $70, iceshark's negative battery cable and ground suppliment made wonders to my car, a REALLY highly recommended product!!!!!

Super heav duty:

 

So, how does one access the ground on the back of the bell housing on the 'S'?

 

I'm sitting on a pretty similar problem.
Tach and boost gauge don't work, temp gauge always reads high. If the car is remotely warm, the gauge is pegged well into the hot range. fuel gauge never reads above 1/4 tank, oil pressure gauge won't top 2 bar, and volt meter is well below 10V. The operation of all the interior electrical gadgets seem to indicate that I do indeed only have 10V inside. Power windows are slow, sunroof nearly doesn't work, same with hatch release, lighting etc. Even my headlights are extremely dim. However, when the car is running, I measure 13.6V at the battery, and at each and every one of the fuses. Where should I try looking?

 

So, how does one access the ground on the back of the bell housing on the 'S'?
__________________
From the top..It is a real PITA. Just follow the cable from the battery box.