Thread: OBD2 -> OBD1 stepdown harness diagram

^^^ broken links

Really? I just uploaded the pics and I am still on the photo album now.

Don't know what's going on... someone who can help me to post the diagrams?

Pretty sure this is what you're attempting to do:

OBDII


OBDI

Now for my next question:

What exactly are you attempting to do?

If you're trying to use a Consult cable for tuning, I see what you're doing.

If you're trying to communicate for the purpose of emissions, this will not work. The protocols are different, but the same (if that makes sense).

If you take an OBDII car, and have it scanned for readiness codes with an OBDI ECU installed, the communication will fail due to differences in the communications link.

Thanks Cliff, yes, I was trying to post these diagrams.

The first diagram is same as what I have for OBDII, which was straight out of my 200SX SE-R factory service manual.

As for the second pic, I have a SR20DET one, I think its from a JDM model car (it has some Japnese in the diagram). It has a clearer lable for the data link plus pins - no. 23 (CHK), no. 15 (TX|), no. 7 (RX), no. 14 (CLK), no. 5 (Ignition pulse O/P), no. 25 (Exhaust temp warning).

I see what you mean, I was trying to achieve all the above. Maybe I will be better off by piggy back a seperate consult plug out from the OBDI side..? I recall that the stepdown adpator made by Zero also have data communication function, and that was why I thought the conversion would work and still be able to use the original consult plug in my SER.

I'm not sure how your emissions works, or if they even do emissions where you are located.

In my experience, they scan your VIN, which reports your model year of vehicle. This alone tells them to test using OBDII. If the OBDII test tries to communicate with an OBDI ECU, the communication is not established, and the test is an automatic fail.

If all they do where you are at is look at the car physically, smog the car with a sniffer, and check the dash for a CEL light, you'll be okay. It's when they plug the scanner into the OBD port that they catch you.

Hi Cliff,

Thank you for the advise.

I am in Taiwan right now and my car is an import from US (got it back from CA in '01), and so there would be no problem of the model and year (hence determining OBDI or OBDII) because they don't sufficiet info on the vehicle.

However they do occasionally plug into OBD port to check the car if they suspect that the vehicle's been modified, and I just want to make sure the port works. I think it would be a good idea to do a piggy back a consult port (OBDI) from the adaptor, and wired it under the dash to replace the original one. At least if they try to connect it up it will still work..

http://www.wretch.cc/album/show.php?i=charleshsiao&b=2&f=1165034441&p=2

This is the consult plug that I have, and the pin info:

OBDI
(1). Rx (pin 7)
(2). Tx (pin 15)
(3). CLK (pin 14)
(4). 12V Ign (pin 38/47)
(5). GND (pin 39/48)
(6). CHK (pin 23?)

OBDII
(1). Rx (pin 64)
(2). Tx (pin 65)
(3). CLK (pin 68)
(4). 12V Ign (pin 56/61)
(5). GND (pin 10/43)
(6). CHK (pin ?)

Any info on this?

ps. strange that I can post any pictures ??... I double check that the url for my photo album definitely is working fine....??
(Same pic from sr20forum.com and some info: http://www.sr20forum.com/engine-management-tuning/249988-consult-plug-pins.html)
Apologes for referencing the link to sr20forum if this is not appropriate.....

Linking is fine. I'm on my phone right now so I'll respond later unless someone else chimes in