Thread: OBD2 -> OBD1 stepdown harness diagram

Thank you Cliff, greatly appreciate all your assistance!

Hi Cliff,
If I would want to include this into my stepdown adaptor I only need to conned:

OBDI
(1). Rx (pin 7)
(2). Tx (pin 15)
(3). CLK (pin 14)

to

OBDII
(1). Rx (pin 64)
(2). Tx (pin 65)
(3). CLK (pin 68)

Connection for no. (4). 12V Ign and (5). GND were already covered in your previous conversion table so I don't need to split and do the connection again?

Also if you have any info on (6). CHK that could further clearify (the link to sr20forum someone responded this CHK is not used for consult diagnostic).

Thanks again for your help!

Cheers,

My guess is that "chk" is referring to a loop check between the consult device and the ecu? In my mind, it's use is to determine whether the device should start communicating with the ecu or not?

I really don't know why the chk terminal pin is there, or what it's used for...

By the way, I saw some question about CONSULT but couldn't tell if the issue was ever resolved in this thread. The original spreadsheet didn't include it because I didn't need it. Here's the reference:

OBD1 ----- OBD2
14 --------- 68
15 --------- 65
7 --------- 64

It is in my forum but not in the project section of my main website.

Thanks, that is in fact the question that was raised. Appreciate the insight!

I noticed this is missing the EGR pinout. Any reason?

OBD1 ---> OBD2
8 EGR temperature sensor ---> 62 R/B EGR Temperature Sensor

Back to this, I'm about to do the stepdown. When connecting the wires together im guessing solder is ok, unless im using magic to connect them to the B14 ecu side.Any other tips I should know prior to doing this...


thank you

You have to use solder, no other way.

what about this info? or should i just use whats on the 1st page...


i guess this is the easy part, attaching wires to the ecu side will be the P.I.T.A.... lol

Man it's a painful process I spent couple days in the row doing it. Screwing it up, and redoing some wires.