Help me identify these Plugs under my drivers seat of my 91 C2 Targa

skotter · skotter's Garage

1991 Porsche 964 C2 Tiptronic

Top Photo is of a plug in the back under the seat and the bottom photo is the 2 plugs in the front. The two in the front have jumpers on them. The reason i'm asking about these is because I was connecting the straps on my new Lloyd mats under the seat and I must have bumped something...not sure if it was one of the plugs with the jumpers or not. At any rate the next time I started my 91 C2 tiptronic I got the tip hazard light and it was in limp mode, shut it off and started it a few times same problem.

So I got under the seat and checked the connections to the TIP ECU and all looked good. So I checked all the other connections and the one with the green jumper seemed to be loose. Put the jumper back in all the way and started the car and the tip light was off.

So...might not be related but I guess it's time to identify what the 3 plugs are. NOTE: I've only owned the car 2 years or so and I'm assuming the jumpers are not there in a stock configuration:-)

Any help identifying what those are would be MUCH appreciated.

skotter · skotter's Garage

Anyone? :-)

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by skotter

1991 Porsche 964 C2 Tiptronic

Top Photo is of a plug in the back under the seat and the bottom photo is the 2 plugs in the front. The two in the front have jumpers on them. The reason i'm asking about these is because I was connecting the straps on my new Lloyd mats under the seat and I must have bumped something...not sure if it was one of the plugs with the jumpers or not. At any rate the next time I started my 91 C2 tiptronic I got the tip hazard light and it was in limp mode, shut it off and started it a few times same problem.

So I got under the seat and checked the connections to the TIP ECU and all looked good. So I checked all the other connections and the one with the green jumper seemed to be loose. Put the jumper back in all the way and started the car and the tip light was off.

So...might not be related but I guess it's time to identify what the 3 plugs are. NOTE: I've only owned the car 2 years or so and I'm assuming the jumpers are not there in a stock configuration:-)

Any help identifying what those are would be MUCH appreciated.

The main harness to the DME has 2 pigtails, a 2pin and a 3pin, these are bridged in different ways to recall different DME maps.

a US tip w/ cat. should have a plug 944.612.525.01 installed and the 3 pin plug empty

skotter · skotter's Garage

OK. So my car does NOT have a cat. It has a cat bypass I know that for sure. Are you talking about the 2 plugs in the front of the seat or the 1 plug in the back. The back has no bridging the front 2 both do. I'm not sure if I put the bridging back in the correct holes in the 3 pin one( IE slot 1 and 3 or slot 2 and 3, however the tip light is off and the car appears to run properly.

Am I explaining it clearly:-)

Justin@Athens · Justin@Athens's Garage

Bill has this exactly right. The only time you would have a jumper in the 3 pin connector is if your car was originally sold in California or Japan.

skotter · skotter's Garage

Thanks for all the scoop guys!

OK here is a better pic of how it's set. You can see the colors of the wires. It does have 3 holes to put the jumper in. I guess depending on which one you consider one or 3 it's in either 1/2 or 2/3. Again this is the one in the front of the seat not the back.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by skotter

Thanks for all the scoop guys!

OK here is a better pic of how it's set. You can see the colors of the wires. It does have 3 holes to put the jumper in. I guess depending on which one you consider one or 3 it's in either 1/2 or 2/3. Again this is the one in the front of the seat not the back.

It looks like someone made a DIY bridge
for 964 tip w/ cat oe 2 pin is brdged againt grongd w/ 944.612.525.01 and the 3 pin is open

for 964 tip Japan the 2 pin is the same as above and the 3 pin is bridged to battery+ w/ 928.607.421.00

for tip w/o cat oe 2 pin is bridged against ground as above and the 3 pin is bridged against ground w/ 928.607.422.00

skotter · skotter's Garage

So Bill, you're saying I have it set correctly for Tip without cat? That is what I want to make sure I have set currently

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by skotter

So Bill, you're saying I have it set correctly for Tip without cat? That is what I want to make sure I have set currently

I'm not sure what provisions Porsche implemented on the cars w/o a cat

one is that the O sensor is likely to be extraneous and the car runs solely off the built in maps rather than responding via O sensor input

another maybe higher octane leaded gas, running on the typical US ethanol blend may or may not be sufficient

skotter · skotter's Garage

I run 91 octane no ethanol. It does have an O2 sensor that is hooked up. I bought the car and it had the cat bypass so i'm basically now getting all the information. It just seems weird to me that the way to do this would be to jumper stuff on a connection that appears that it should be connected to something or done differently. My guess is this jumper setup isn't Porsche OE but something the previous owner or his mechanic did:-)

The car appears to be running fine so my guess unless someone tells me different is that I've got the jumper set correctly.

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by skotter

I run 91 octane no ethanol. It does have an O2 sensor that is hooked up. I bought the car and it had the cat bypass so i'm basically now getting all the information. It just seems weird to me that the way to do this would be to jumper stuff on a connection that appears that it should be connected to something or done differently. My guess is this jumper setup isn't Porsche OE but something the previous owner or his mechanic did:-)

The car appears to be running fine so my guess unless someone tells me different is that I've got the jumper set correctly.

That green jumper is certainly after market

The cat bypass on your car is likely aftermarket too.

When new, a cat less car would have been listed as option M150 and would not have a cat or O sensor installed at all. Since you do have an O sensor a previous owner must have installed the cat by pass and the jumper you see. An M150 would have a premuffler in place of the cat.

skotter · skotter's Garage

Yes I know the cat bypass is aftermarket. What would the jump\bridged connections look like stock?

I'm having a tough time finding any of this information in books or online to help me better understand all of this. If anyone has any resources as well i'd love to review.

mikedsilva · 04-05-2015, 03:38 AM

did you get any further with this?
I just checked my car, and both my 3 pin plugs are not bridged... but the little 2 pin plug is bridged.
Reason i ask, is that my tip warning light has just come on and is in limp home mode... no idea why...

skotter · skotter's Garage

Hi. I was told my configuration that is pictured is the way its supposed to be. When I knocked the one side out is when it went into limp mode. The car is in storage right now so I can't take anymore pictures.