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Old 07-17-2017, 11:10 AM   #1
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Do 97-99's have OBDII wires for sensors?

I was wondering if in the SPBs we can pick off Oil Pressure, Oil Temp, Water Temp, Tranny Temp off the OBDII?

Let me clarify -- what I am after is physically splicing a wire and routing that to my Traqmate as a digital or analog input.

I'd prefer to send the to my Traqmate data logger and TD rather than add a bunch of gauges and new senders (unless I have to)

thanks,

Mike
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Old 07-17-2017, 12:03 PM   #2
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Mike, the OBDII system in these cars reads off the DME, not the sensors directly. The sensor are sending fractional or low voltage signals to the DME, which converts them into what are referred to as "PID's", which are the reading values. Tapping into the sensor wiring will only give you the voltage. You can read a significant number of the PID values directly off the OBDII port however.
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Old 07-18-2017, 06:18 AM   #3
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If your Traqmate logger can read K-line your all set and should be able to get Water temp, Throttle position, etc.

Most loggers use CAN for data from the ECU. Unfortunately Porsche was a bit behind other marques in getting that protocol to their ECUs and didn't really get it together until around 2006.

K-line unfortunately has very slow sampling frequencies (<10Hz) so there is some delay in sensor readings.

For Oil pressure you need to install a sensor since the 986 doesn't have one.
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Old 07-18-2017, 07:11 AM   #4
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Are you sure of that? How dies the low oil pressure light function without that type of information?

EDIT: The wiring diagram shows an oil pressure switch, with a GN/WT wire that feeds directly into the White plug (position 6) in the instrument cluster. Not sure if this is an on/off voltage or if voltage is related to oil pressure in a linear fashion that could be used with traqmate. It would be easy enough to put a meter to it and rev the engine to see if there is a voltage increase with increased oil pressure.
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Last edited by Lemming; 07-18-2017 at 07:51 AM.
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Old 07-18-2017, 07:45 AM   #5
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Quote:
Originally Posted by Lemming View Post
Are you sure of that? How dies the low oil pressure light function without that type of information?

EDIT: The wiring diagram shows an oil pressure switch, with a GN/WT wire that feeds directly into the White plug (position 6) in the instrument cluster. Not sure if this is an on/off voltage or if voltage is related to oil pressure in a linear fashion that could be used with traqmate. It would be easy enough to put a meter to it and rev the engine to see if there is a voltage increase with increased oil pressure.
This engine uses and pressure switch preset around 5PSIG to trigger the dash light. to get pressure readings, you need to replace it with a variable sender.
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Old 07-18-2017, 07:53 AM   #6
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Yes, I replaced the existing sensor with a VDO and just tapped into the wire in the cluster as I was not sure of the stock sensor output.
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Old 07-18-2017, 01:41 PM   #7
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The 911 had a dual temp and pressure sensor for the 99 model year. Probably the only reason one would put a 996 dash in a SPB (it's legal) if you don't have data acquisition.

Generally it is best to have another set of sensors for your logger if you don't have CAN from the ECU. I know it ends up being more $$$, but the lack of gremlins from splitting signals/wires is worth it in the long run.

I use AIM, have an MXL in the Boxster and an MXL2 in the M3. The Boxster has it's own set of engine sensors for the MXL + Steering angle + Brake pressure. I use the BMW version of CAN for the M3 which while it offers quite a few channels it still doesn't have oil temp or pressure. Separate sensors required for those channels.
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