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Old 01-23-2019, 07:47 AM   #7
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seningen's Avatar
Join Date: Jul 2008
Location: austin
Posts: 763
*** SOLVED ***

The rain, the battery running down, battery cables, kill switches, fuses, relays, DME, Immobilizer, Key RFID, etc

None of that had anything to do with it

Shortly after I bought the car
I installed a traqmate system, including a traqmate USB to control the cameras and data acquisition.
That system had been in the car for nearly a year prior including 2 or 3 event weekends with no symptoms whatsoever.

There was a pin on the traqmate usb labeled 5v with the input analog pins. The documentation. Is poor, so I hooked up 5v off the obdii port after having found you can get 5v off of there (I don't remember how that was determined, probably internet)

I eventually had to buy a street car to have a known good reference. She showed up late last week and was keen to success.

After checking things back and forth between the street car and the Spec Boxster, including triple checking the DME.
I decided some input to the DME must be wrong and is causing the DME not to let the car start.

So I wrote out all 88 pins and made a chart and one by one probed each signal in the street car, and then did the same in the spec boxster.
After probing all the signals between the street car and spb I noticed only a couple differences, one was the software voltage pin which only
connects to the obdii port.
Street car was 0v, spb 5v. Also the durametric could talk to both dmes, but on the spb, all live data was defaults and voltage was 0v, regardless of the DME,
while on the street car with both DMEs I got live data.

I went home and thought about where the 5v could have come from, and I remembered the traqmate usb had a 5v pin.
I also remember sourcing that 5v from the OBDII connector as that is what I had found online to do. My spidy senses
were tingling -- was I on to something?

About midnight last night, I found some documentation online on the old traqmate system. It wasn't very good, but I could see a photo of the pins labeled on the USB box
and blew up the picture. , It wasn't clear, but it looked like 5v was an output
Not an input!!! I had figured at the time that the 5v was needed for the analog data acquisition, not the other way around. Surely it couldn't be that simple.

After a sleepless night
I ran out to the shop this morning, unconnected the traqmate usb
And she fired right up

I think the 5v put the dme into some sort of program mode or something, disabling its ability to start the car.

Why did jumping it work without battery?

I think once you got 14v, the 5v wasn't high enough to put it in the program mode...
I also think that once you get running, the DME just does its thing -- OR, the Boxster's alternator put out 14v, and once again
the 5v input was read as a low, not an assert.

Further complicating the matter was the small fuse box that was added for accessories that I had tapped off of for the traqmate 12v hookup
is janky, and I don't think it has a good internal connection. That's getting yanked and a new, and more accessible unit will be installed.

Just diabolical....

Now I have to put it all back together and get my medical done and sign up for NOLA.

Thank you very much to all who supported my efforts and responded to my posts -- especially Ahsai. If nothing else,
the moral support allowed me to just keep plodding along.
Drivers: '08 Cayenne Turbo, 96 993 Çab/Tip (wife's) & '92 964 Cab
Race Cars: '75 911 RSR Clone & '99 Spec Boxster
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