Looking for OBD connector pin out info... RPM signal

Looking for info on the which pin I can get the RPM signal from on a '99 non-FBW 996 C2. Also which is ground? Looking to pull as much off the OBD port as possible to route to my data logger. Thx,

You can't pull signals like that from OBD. OBD uses a CAN (Controller Area Network) serial communication bus. The data on the CAN bus is digitally coded (think USB, RS232, etc., you can't sniff out a unique signal without first interpreting the data). You need hardware with some type of microcontroller that has the ability to communicate via CAN, which is what OBD readers do. For what it's worth, I design robotics for the semiconductor industry, and I use a CANopen (similar to CAN) network infrastructure for all the motion control and I/O. One machine in particular has 45 axis of motion (45 motors), and over 500 discrete digital and analog inputs and outputs, all talking to one another and being commanded via a CAN bus. A decent amount of data can be piped thru. Edit: perhaps you can sniff the signal that is going to the tach instead? I'm not sure if the gauge cluster is one CAN node, or if each gauge is an individual node, but at some point that tach needs to get a signal that is either a digital PWM signal that you could use or an analog signal that you could use. Problem may be that that signal could be buried inside the tach, but maybe it's not, and is on one of the wires in a harness right behind the or on the cluster. You could also get a bluetooth OBD data transmitter and get an adapter for your datalogger that can extract the data. Most of the bluetooth OBD transmitters are made for smart phones where an app decodes and displays all the info. Maybe your datalogger has a bluetooth option that is compatible with some of these OBD transmitters?

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RPMs are not brought out on a pin. RPMs (and many other OBD parameter data) can be obtained with an automotive test tool (or trip/data logger) that communicates using the car's OBD2 protocol (probably ISO-9141-2 (my 02 Boxster and 03 Turbo) or KWP2000 (my 08 Cayman S). Once the data is obtained it can be viewed in real time if the tool has a display or it can be stored to non-volatile memory for later viewing or downloading to a PC (or maybe now even a smart phone). Sincerely, Macster.

You might try something like this: http://www.dealextreme.com/p/elm327-...r-dongle-16921 Bluetooth OBDII readers. Connect it to your laptop or cell phone and you can data log and view things like RPM in real time.

Sorry to disagree with the previous posters, but the posts above are simply incorrect. On the 5.22. DME used in the '99 car the original poster is inquiring about there is no CAN bus other than between the tip control unit and the DME on the tiptronic cars. The later cars gradually introduced more CAN bus networks carrying more info over the paired wire system, however even the last of the 996 models still carried the tach signal to the OBD port via a dedicated wire. The tach signal is on the OBDII connector at position 9 (Violet/green wire). You can pull ground off of pin 5 (brown/blue wire). Todd

thank you Todd This will be the easiest way to add RPM to my logger. http://youtu.be/XfYmPWpP0ec?hd=1

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Absolutely correct. I pull RPM for my Traqmate off that exact wire.

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You are right, Todd. Your post prompted me to look through the wiring diagrams that I have for some Boxsters (up to '02 IIRC) and in the case of an '00 (just happened to be where the wiring diagram manual opened up) Pin 9 of the diagnostics connector (the OBD2 connector) gets a RPM signal from the instrument cluster. Should have done this to confirm what I 'knew' before making a fool out of myself. Thanks for posting the correct info. Now tomorrow when I have the Boxster at the office I'll connect a break out to the connector and with a scope see if I can figure what the RPM signal looks like. Sincerely, Macster.

Whoa! Thanks Todd! I had no idea, and am really glad to be wrong in this instance! I've had some ideas of what I wanted to do with a tach signal, and now it's easy as pie to get the signal. Sweet, time to start experimenting!

Do you guys pull anything else off the ODB interface ?

And hey, ApexComp, is that your vid? Sweet! I really like that overlay, having tach on there too would be great. Question, how do you sync the overlay with the video? It must all be done in real-time and not post-production, yes?

It was all done post production.... http://www.racerender.com No affiliation.. just a happy customer

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ever get a chance to do this?

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No. I had to take the Boxster in for what turned out to be a bad passenger side window regulator. I won't have the car back until later today (this afternoon) at the earliest. I have my Turbo here to today. I'll see if I can scope its #9 pin, assuming of course the 2003 Turbo's OBD2 pins carry the same signals as the 2002 Boxster's OBD2 connector pins. If not I'll have the Boxster at the office next Monday. Sincerely, Macster.

Pin 4 - Chassis Gnd? Pin 5 - Signal Gnd? Pin 9 = RPM Pin 16 = Batt V ? What are on pins 8, 11, 12 & 13 ? Since data sent from the OBD port varies from vehicle to vehicle I'm not sure what the early 996 makes available. Does anyone know which channels of data below are present on the '99 ? I may hook up a generic reader this weekend if my lazy RL approach here doesn't prove fruitful Of everything there I really just want TPS & Lambda, both of which I can get directly anyway.

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Pins 8, 11, 12 , and 13 are all labeled "discretionary" in the SAE J1962 specification I have. (Same goes for pins 1 and 3. 4 is chassis ground. Pin 16 is permanent positive voltage.) Do you see pin sockets in the pin locations of interest in the OBD2 connector? If no pin socket, the pin is not connected. If there is a pin socket showing then the pin is likely connected but to what without access to the wiring diagram of the diagnostics connector of that particular model of car or access to a PST2/PIWIS/PIWIS2 for that particular model of car to reverse engineer what pins are connected and what they are used for...I'm unable to say what they are used for. Mandated by I guess the fed gov. and some state gov. environmental agencies (EPA/CARB to name two) there is an OBD bus, generally for Porsches this is ISO-9141-2 but not always. (My 08 Cayman S was KWP2000. As the car was an 08 MY I was expecting CAN but my info is Porsche (along with other car makers) asked for and received a pass on switching to CAN in 08.) Newer model years might have switched to CAN. (My Cayman S had a CAN bus but this was the comfort (Komfort in Porsche speak IIRC) bus which in the case of my Cayman was used by Porsche test computer to communicate with the instrument cluster. (The communication was hard to follow -- I captured it with a bus snooping tool/software I have -- and gateways were involved. I captured this traffic to figure out how to clear/dismiss the service light (among other things) but when I lost my Cayman S shortly after this to an accident I lost all interest in doing this.) Except for rpms (in the case of some Porsches at least) and possibly speed (VSS) -- which is manufacturer dependent -- the rest of the data I believe are only available from the engine controller using the OBD2 bus and a suitable communication protocol. At least this is the only way I've been able to obtain this data. But it is really the only way I care to. Auto test equipment I have I use to read this info from a variety of vehicles all the time. Well, not directly except when I have an hand held OBD2 code reader/data logger connected to a car for this purpose. More often and in a number of vehicles the data is read automatically and is stored for later retrieval via a USB or wireless connection or stored/sent at some later time via a cell phone link to a web site and there I can view the data. I can also interact with the car with the right software using this device/cell phone link and have in the car essentially a remote wireless scan tool. Now at the car, your car, in other places there might be test points at some connection that with a proper break out box and details on its pin out these raw signals could be available and with the right electronics could be translated into human readable format. But a wiring diagram is needed to know, unless you can find someone who's already figured this out. If anybody has it would be my guess someone working for a company that offers data loggers/metrics gathering technology for say track cars. They would probably consider this info a business secret and keep it to themselves. Sincerely, Macster.

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Depends what I'm doing. I've pulled rpm, throttle, engine load and speed for race logging, but I've also plotted/logged O2 sensors, MAF, fuel ratio and others for troubleshooting purposes. FYI, I use a bluetooth OBDII similar to the one linked above to datalog with my cell phone. Works beautifully! Had to invest in an external 10Hz bluetooth GPS, as most phones only update about 1Hz which isn't very useful. Still, $25 for the OBDII + $80 for the GPS + $6 for the software is damned cheap data logging w/instant review. Awesome to finish an autocross run and be able to instantly review video with full telemetry! You Tube 3DgNR.jpg

Red = TPS Grn = RPM Yel = Ign Adv Silv= MAF

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+1 and I think thats universal for OBD