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Ever since I've owned the car it has had an alternator error at start up. Here is some background information that is probably important:
- Car is a 2006 Cayman S, with a Tiptronic transmission
- Bought as a project with a broken engine (still unknown what's wrong, but it was bad)
- Engine replaced with one from a 2008 manual car
I had the engine installed at an indy and the install was good, apart from this error on the dash. The error shows up during the initial checks, when the oil is being measured, and before the engine cranks. The alternator is working fine and puts out adequate voltage to the car when the engine is running. Since I have the day off, I figured I would jump into the car and install the original alternator to see if that would clear the error. Everything was going OK up until I couldn't plug in the 2 wire connector. That's when even more confusion began.
Here's what I've learned:
- The auto and manual cars came with different alternators. At the very least, the pulleys are different. The manual cars have a clutched pulley, which the automatic cars do not. Here's the alternators in question, followed by a comparison of the pulley diameters:
Automatic version above, manual version below
Automatic car pulley
Manual car pulley
The issue with the plug on the voltage regulator comes down to how the connector is keyed. That post, and more pictures, will follow shortly.
The difference comes down to this. It's a little hard to see but here's the plug on the harness:
This is a Mercedes housing, of all things
It's a little hard to make out but, on the plug in the picture above, there are 2 slots on the left, and 1 on the right. That plug fits into the alternator from the manual car, as well as the replacement voltage regulator that I bought on the advice of an online expert.
Here is the voltage regulator from the manual car alternator. This is a new part which, when installed, plugged right into the harness: From the manual car alternator, this is the new VR that I bought
Here is the plug on the voltage regulator from the original engine alternator: You can see how it's sort of a mirror image to the manual car alternator
So, here are my questions:
- Why is there only a single voltage regulator offered from vendors? It seems like there should be 2 versions.
- Does the voltage regulator play a role in the start up alternator check that the car performs?
- The harness plug only has a single pin, does it matter which pin it connects to on the voltage regulator?
My plans:
- I put the new VR on the original alternator and will hook things up electrically. Maybe that solves the problem.
- I will contact the indy shop to see if they had to mess with the harness plugs to get the alternator to connect.
Any insight into what the heck is going on would be greatly, greatly appreciated. This has been driving me nuts for a while.
You mentioned that a shop did the swap. Presumably that had to swap the connector from the donor harness (manual) with the connector in the car (automatic). It may be that the shop got confused on which pin to put the terminal in. Try swapping the pin location of the terminal and see what happes.
However, since the pulley is different (manual is larger and uses a clutch) I would recommend that you use the alternator designed for the automatic. See if you can find the original connector on the harness that was associated with the auto and pull the connector of that.
But as you discovered, porsche changed the alternator in 08 (or before, I'm not sure exactly when). So the wiring harness needs to match the alternator.
You can run an 08 alternator in an 06 car (im doing it). You have to change the plug at the alternator (so the key mechanically fit)... but also move the alternator wire to a different terminal on the ECU.
@jscott82 : Thanks for chiming in, that's new information to me. I have read that there is sometimes a need to swap wires at the ECU plug, but I had never heard about it being tied to a model year change due to an alternator design revision; one more variable in this whole situation!
Based on your experience, is the '08+ voltage regulator going to be compatible for the check, when installed on an '06 alternator? I'll run that check this evening, I'm just trying to determine the regulator's role in the check sequence. If it's just a plug incompatibility issue, it looks like I have an '08 plug installed on my harness so as long as the internals of the alternator are what is causing the incompatibility during the check, maybe this will be enough to get things sorted.
Finally for this post, is there good information on how to free up the pins on these particular connectors? I have the tools to remove the pins, but it looks like there is a locking mechanism on the housing itself.
this is quite odd indeed. I have read others have had the same error but alt and battery work perfectly fine. some have had success with swapping the pin on the DME. I have the same error on my 07 987 BS and it came up when i had an 02 sensor that failed and took out my DME (wild I know) I bought a used DME on ebay had it programmed by a local ECU shop and got me up and running but I get this error. swapping pins on my DME didn't make a difference. I'm wondering even though the DME part numbers were the same it must be a different MY/ manual vs tip causing my error...
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987.1 Alternator Technical Help Needed
