Help with cables

**highwayman** · 09-23-2009, 06:48 PM

I am in need of schematics for cable to connect an elm327 to an obd2 connector on a 1994 corvette. I know I can buy one but I already have the cable and db9 and obd2 connectors.

Please help
Thanks

**Aberk** · 10-05-2009, 10:11 AM

Your 94 Corvette is OBDII?

**Aberk** · 10-05-2009, 10:23 AM

A quick google search yielded these two images.

**highwayman** · 10-05-2009, 11:54 AM

Thanks
I have this cable
this car hac
s obd2 connector but is obd1 so data is on pin 9 of obd conn

**Aberk** · 10-05-2009, 12:14 PM

I am pretty sure the ELM wont work with OBDI, but maybe some one else will chime in and say differently.

**malcom2073** · 10-05-2009, 12:21 PM

Your car is likely OBD1, specifically GM's ALDL. You need this:
http://www.aldlcable.com/sc/details.asp?item=aldlobd2

Also, be aware that OBD2 software will not work, you will need software that is specifically ALDL compatible.

**highwayman** · 10-05-2009, 07:12 PM

Yes this is probably the cable I need but, I hate to think of spending $60.00 when I have all the parts here and only lack wiring schematic.

**malcom2073** · 10-05-2009, 07:27 PM

Oh, you want to build it yourself?

http://www.astb91.dsl.pipex.com/ALDL%20circuit.html
Or a cheaper alternative:
http://syclone.invisibill.net/cablewires.gif

For that last one, you can usually pull 12v off of one of the other pins on the diagnostic connector, not sure which one though. Poke around with a multimeter

Personally I spent $80 and bought a USB aldl cable from Moates.net. Very reliable, very awesome, but also very expensive.

**highwayman** · 10-06-2009, 11:39 AM

thanks guys

I am only looking to make the cable not the interface
I really only need the schematic to make a cable like the
http://www.aldlcable.com/sc/details.asp?item=aldlobd2

**malcom2073** · 10-06-2009, 05:08 PM

That cable has the interface inside of it, most likely a MAX232 similar to the first link I pasted. If you just make a straight-through cable, you are going to either fry your computer, or fry the ECU's diagnostic port. The ECU has single wire serial communications, using 0-3v as low, and 9-12v as high. Your computer uses (at the extreme) -24-(-3) as low, and 3-24 as high. That's not gonna play too nice.