spudly13 Posted November 20, 2013 Report Share Posted November 20, 2013 I know i know its not datsun related, just hoping someone here could possiby give a little insight. My drift car is an e30 with an lt1 out of a 96 firebird formula. I found some software for checking DTCs and live data etc. I wired up the obd2 port and bought an elm327 usb cable. So the problem. ecu on, engine off, i can get it to connect and view the trouble codes. But as soon as i start the engine the usb disconnects from the laptop and disappears from "devices and printers", engine off, unplug, plug back in it will reconnect. Any input appreciated! Quote Link to comment
flatcat19 Posted November 20, 2013 Report Share Posted November 20, 2013 Will it even show when running or not at all? Unplug and plug back in while running? Quote Link to comment
spudly13 Posted November 20, 2013 Author Report Share Posted November 20, 2013 No live data will show up while running, ive tried unplugging and plugging back in while running, it wont connect because the laptop isnt recognizing the usb while the engines running? when the engines off though i can see some certain live data, such as coolant temp, intake air temp, throttle percentage. Quote Link to comment
flatcat19 Posted November 20, 2013 Report Share Posted November 20, 2013 And you have the pinout for the DLC wired correctly? I'm trying to find the pinout to follow along. Not having good luck. Quote Link to comment
spudly13 Posted November 20, 2013 Author Report Share Posted November 20, 2013 http://www.lt1swap.com/fuseblock_obd2port.html Edit: scroll to the bottom of that link^^^ Yes i "believe" i have it all wired correctly, Someone else mentioned "to much electrical noise" but im not sure what that means. Quote Link to comment
spudly13 Posted November 20, 2013 Author Report Share Posted November 20, 2013 And heres the ecu pinouts http://www.lt1swap.com/lt1_pcm_pinout.htm Edit: i have pins 4 and 5 grounded, Pin 16 is 12v off ignition switch, and as im looking back over those pinouts i need to go out and verify which other pins im using. Quote Link to comment
flatcat19 Posted November 20, 2013 Report Share Posted November 20, 2013 Question...Can you read mode 6 on your scanner/laptop? Quote Link to comment
flatcat19 Posted November 20, 2013 Report Share Posted November 20, 2013 It sounds like something is killing the ignition switch signal when running. Can you verify that? Quote Link to comment
spudly13 Posted November 20, 2013 Author Report Share Posted November 20, 2013 while running i have 12 volts at pin 16 off the ignition yes. And the software im trying to use has a tab for mode 6 testing but i cant get it to do much of anything Its to dark to try and verify all the pins and getting to late to move it into the shop (dont wanna piss of the neighbors) ill move it in tomorrow and finish checking over my wiring. Also, i just noticed while i tried it again, while running it doesnt just disconnect, it actually disconnects and reconnects erratically but never stays connected for more then a few seconds at a time Quote Link to comment
flatcat19 Posted November 20, 2013 Report Share Posted November 20, 2013 Maybe not a secure enough connection or one of the outputs on the DLC is running PWM/pulsing. Quote Link to comment
oldskoolvws Posted November 20, 2013 Report Share Posted November 20, 2013 Are the baud rates matching and supporting as I'm guessing your going all serial and not CAN-bus. With engine off, it's only reporting X-data, with engine running it's reporting XXXXX-data. If the baud is too slow or not matching (parity, etc), you can get communication faults. If it's an ignition power fault, typically there will be an undervolt code thrown. Quote Link to comment
flatcat19 Posted November 20, 2013 Report Share Posted November 20, 2013 Are the baud rates matching and supporting as I'm guessing your going all serial and not CAN-bus. With engine off, it's only reporting X-data, with engine running it's reporting XXXXX-data. If the baud is too slow or not matching (parity, etc), you can get communication faults. If it's an ignition power fault, typically there will be an undervolt code thrown. Good thought. Quote Link to comment
spudly13 Posted November 20, 2013 Author Report Share Posted November 20, 2013 i will try all the different baud rate options, i was told most cheap cables use 38400, and the nicer ones use 115200. I was trying to use 38400 and havent actually tried any others, yet. Quote Link to comment
mhub91 Posted November 21, 2013 Report Share Posted November 21, 2013 is the USB cable a data cable? Or just some generic USB charger you found laying around? Quote Link to comment
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