Low range switch not working

[jacobpackard]

Hey guys new here to the forums and owner of a new to me 2004 Cayenne S. Recently replaced the driveshaft and noticed the rocker A switch for low range settings is no longer responsive. When I turn the car on all 3 lights flash once then nothing. I put the car in N, apply the brake and try to run through settings and still see nothing both on the dash or on the switch itself. My question is does this look like a differential pump issue? Crankshaft control box or faulty switch? I dont envision myself needing the low range so am I ok to not worry about it? Any help would be appreciated. 

[hahnmgh63]

Your best bet if your going to keep your Cayenne for a while is to get the Durametric software and install it on a laptop so you can scan all OBDII codes plus most of the Porsche specific codes. With that said, it could be the switch but the High/Low range solenoid from '04~early '05 is known to be weak and was superseded with a newer part number so that could also be your problem. You may have to take it to the dealer unless you can do some troubleshooting without the Durametric. Maybe try the wires at the Solenoid to with a Multimeter to see if you are getting power when you move the switch.

[jacobpackard]

Thanks for the reply! Is the solenoid part of the pump or something that can be replaced separately? So I take it that this part of the car not working wont always through a dash code? Also sorry but last question any damage in just not doing anything with it? 

[hahnmgh63]

This is the part I am referring too:

http://www.ecstuning.com/ES1454212/  Sonnen has it for $671 but you might find a good one on Ebay. If you go used try to find one out of an '06 ~'10 Cayenne. Shouldn't be any problem in driving it as it is but it would be good to get it scanned to be sure. Usually you will get a 4WD fault on the display.

[bigbuzuki]

Check your fuses that supply power to the transfer case control unit and servo motor.

Some variants also have a servo motor on the rear differential. Check.

Although you don't use low range, the servo motor is always active even in normal range.

The servo motor drives a cam assembly inside the transfer case, which controls the torque split between the front and rear differentials via friction disc assembly.

Get it fixed promptly, as more serious transfer drive issues can result as the cam will not be in its optimum position, which can lead to premature failure of your friction discs inside the transfer case.

Edited July 7, 2014 by bigbuzuki

[hahnmgh63]

Good to know Bigbuzuki. I always figured the Torque split was just a conventional limited slip or a Torsen (like Audi).

[bigbuzuki]

Hahnmgh63, I am not sure if there is a Torsen setup inside the transfer case. Here is an excerpt from the Porsche Service Information Technik manual regarding transfer case operation.

Using sensors, the active electronic system continuously measures traction at the wheels, as well as vehicle speed, lateral acceleration, steering angle and operation of the accelerator pedal. From this, the system automatically calculates the optimal degree of locking for the differentials at the drive axles. In this way, more power is applied at the front or rear wheels, depending on the driving situation. If, for example, a difference in speed is detected between front and rear axles through the wheel speed sensors (both in High Range and in Low Range), the electric motor (8) is activated and the curved disk is rotated. The disk presses on the lever (10) with a cam and the lever compresses the clutch disc pack (15). Engine torque is now transmitted to the axle which can transmit torque.

Edited July 8, 2014 by bigbuzuki

[hahnmgh63]

Sounds like a variable ratio limited slip then with Clutch packs. Thanks