Rad Fan Runs Continously

[NelsonMX]

Hi all,

I returned home after a 10 day trip. I forgot to put the Cayenne battery tender on before I left so I figured I may have a problem starting the car as my battery is a few years old......Anyway, it started right up.

However, when I got home I noticed the rad fan was on, and on shutdown it continued to run. In fact it ran long enough to drain the battery. I put the battery on charge for several hours. Unfortunately it didn't resolve the fan issue. Next step was to buy a new battery. With the new battery in all was normal but as I step outside the car the fan comes on and goes off several times........I hooked up the Duremetric and the fault I am getting is P0460 short to ground or open........I checked the connector at the fan, the wiring at the fan module, and the connector at the temp sensor, but I suspect I have a bad ground.

Does anyone know where the grounds are located for the fans? Or has anyone had a similar problem?

In the meantime I have disconnected the rad fan connector to save my new battery......

Bob

Sorry, I should have added that I have a 2004 CS.......

Edited October 29, 2010 by NelsonMX

[wvicary]

There have been some issues with the coolant temp sensor and the fan speed control module.

[NelsonMX]

Thanks wvicary...

I have a temp sensor which I'll change first. Do you know if the fan module can be changed separately? The local Porsche dealer tells me I have to change both fans and the support which includes the module. They claim it can't be purchased separately....

Bob

[wvicary]

I believe your dealer is correct. The module is part of the fan assembly but check with Sunset Part for the newest part number and verify that information.

[NelsonMX]

So here's the update on this issue.

I changed the battery as I had it load tested last year at this time and it was serviceable but about three year old and I didn't want to take a chance as this is my winter car. I had hoped the battery was the cause, but unfortunately it didn't solve the issue. The fan started up in high speed (limp home mode apparently) immediately. My temp repair was to disconnect the fan at the connector on the fan support.

Yesterday I wrang out the wiring as per the manual with all grounds and voltages checking as per spec. The fan module was clean, with no signs of external corrosion. Unfortunately there is no real way to check it out further. For this fault the manual uses a lot of elimination processes. That is, connecting new units to ascertain serviceability....I didn't have a new units other than a temp sensor, which was OK.....

In doing the continuity checks I had the connectors off for the fan, module , and the DME. All looked good. The only thing I did find was the module connector wasn't seated properly. When reseated the fan operation returned to normal. So, that was the fix for this problem........

Brgds,

Bob

[Loren]

Was there corrosion at the connector?

If so, I would clean it with electrical contact cleaner and use a shrink tube over the connector.

[NelsonMX]

Hi Loren.....

No corrosion at any of the connectors. A lot of dust and dirt on the outside, but clean on the inside. Sorry, I should have stated, I cleaned the outside of the connectors before opening them, and I cleaned all connectors internally with contact cleaner before re-seating them.

I haven't put any heat shrink on them as yet. I just want to make sure the problem is cleared, so I'll give it a week or two. I'll be doing an oil change shortly so I'll have a look then and seal them up when I do.

Bob