OBD-II Protocol

[Jap GT300]

Does anyone know which protocol the J-Spec and UK OBD-II ports are?

J1850 PWM
J1850 VPW
ISO9141-2
ISO14230-4

I believe there are only these four types.  I have found a cheap supplier of OBD-II readers for all 4 so if we determine what protocol works where than it should help out a lot of J-Spec owners.

Thanks Adam

[Jap GT300]

Also am i right in saying that we have a 'type A' diagnostic link connector

[Tem]

I believe we have ISO9141, so I assume UK has the same.

J1850 is SAE and that's used in US (cars built there, not imports).

I suppose that leaves ISO14230 to J-spec cars, if they aren't compatible with the ISO9141.


I thought the connector itself is same to all, but the pins in use vary from protocol to protocol and the ISO/SAE defines that.

[Jap GT300]

Also am i right in saying that we have a 'type A' diagnostic link connector

I meant Toyota in General.  There are two type of OBD-II connector though A and B

[Tem]

There are two type of OBD-II connector though A and B

Oh...I've never seen anything but the one we have as well  s:oops: :oops: s:oops:  

What's the other connector like anyway?

[spit]

I was under the impression that connectors are physically the same, only the wiring & protocol differs. I haven't come across a Type A and Type B  s:? :? s:?  
http://www.avsautomotive.com/obd/eobd_obdii_connector.html

[Jap GT300]

Theres not much in it, but they certainly arent compatable

Type A


Type B

[Jap GT300]

As well as variations for transmitting the information there is also a variation from different continents.  I think this is why we can't get a J-Spec OBD-II reader.

Everyone talks about OBD-II and EOBD variations but in Asia they also use JOBD with ISO

[Jap GT300]

Scan Tool have just relesed this cheap little unit which seems to cover all protocols and works in OBD-II, however it doesn't say if it is EOBD and JOBD compliant.

 m http://www.scantool.net/products/elmscan_5.htm m

$139

[spit]

Looks from your diagrams that an A-plug will fit a B-socket but not vice-versa Adam.

I'm chatting with a US firm at the moment who are adamant that their diagnostic kit'll work with JDM....but I'm not confident as they're just a supplier offering no Spec details  s:shock: :shock: s:shock:  .

Maybe we should arrange a sale-or-return with someone on the understanding that - if it works - we should be able to drum up at least half-a-dozen orders? Club power and all that!

[Anonymous]

If you are able to confirm somehow that the reader does read J-spec OBD2 then I would also be interested.