Heidi Ho guys. I haven't been on here in quite some time, but I need help in determining the best process/steps in order, to find out why I have the Ol' Transmission 4-wheel-drive light coming on. I know it can be a few things, but I'm just wondering the best order of things to try. I have the codes 2039 (Transfer box potentiometer) ....2053 (Transfer box control module) ....and 907 (Load management operat. on vehicle electrical sys/DME control module). Those are the ones I hope to fix first. Also rear hatch light/code eventually. The 4-wheel-drive malfunction light hasn't been on long and I can't feel anything that has changed with driving. I'd be OK with it, but about to sell her. Actually runs great and pulls my boat with ease.

I'm pretty sure it's not the battery because it takes a bit of driving to make it come on and the Alt. gauge is perfect. I haven't noticed any issues starting her or other things that would make me think it's the battery. I don't have any blown fuses. This Cayenne S is 2005 and I do NOT have a second battery in the back.

I'm guessing it's probably the control module, but I don't want to get a new one and possibly have it blown by a short coming from the transfer case electric motor or something.

My tires are all in good shape and are all the exact same (I've heard about tire wear causing the trans light to pop on)

I haven't changed the transfer case oil yet.

If the trans is switched to low, locked, it does jump a bit, but not anything that seems really off to me.

I don't want to replace the transfer case in case if it is actually the control module. Unfortunately, I do not have any buddies with a cayenne anymore to borrow a transfer case from for testing. : (

I'm about to try and see if the voltage drops below 8V when starting, but sucks to be by myself on this one. Wouldn't that cause the light to pop on right away if it was dropping below 8V on start up?

I know many of you guys know these PIG's inside and out and causes for most codes. Please direct me in the best course of action to solve this issue. I really appreciate the advice. Thanks in advance.

I'm using the Schwaben to identify the codes. No longer have the Durametric. I go through Porsches kinda fast and I only had the enthusiast version.

 

I just bench tested the transfer case motor and it is functioning as I would expect. I just put 12V to positive and neg motor wires and she turns with no problems at all. Hummmm. What next?

 

Kinda sad how this site seems so dead. I have loved this site for so many years and got to learn a ton. Anyway. An update for maybe someone else to benefit from.

I decided to remove the transfer case motor and I disassembled it. It was full of black dust. I noticed the motor bushings looked only about 1/4 worn, so cleaned everything with electronic cleaner, including ever wire connection that has anything to do with the motor or module. I figured out how to bench test the motor with a 12V source and after I got it all cleaned and together, it worked fine. Seemed strong. I decided to go ahead and put new transfer case fluid in, using $12 Valvoline TCF and also reused the two plugs with Permatex thread sealer. I marked the plugs and turns from removal, then aligned the old plugs back to the exact same spot. Dry as a bone so far. Doing these simple steps and spending under 20 bucks fixed my fault codes. No more dash light coming on either. I'm really happy that worked without needing a single part or paying anyone for the fix. I believe it was all because the transfer case motor was just dirty. Now onto the headliner and hatch warning light. LOL Peace all!