mx5cartalk.com

Hey guys,

I've been looking into retrofitting an OBD2 port to an NB8A to allow use of a ScanGauge type tool. From the pictures of OBD2 ports on the American forum, it looks like it is using the ISO 9141 protocol with a single data line on pin 7.

Looking at the US wiring diagrams, it looks like this data line comes from pin 1D on the ECU as well as coming out in the diagnostics connector on the top row of pins, second from the left. All the other pins required for an OBD2 connection appear to be present in the US diagnostics connector too (pin 4 ground, pin 5 sensor ground, pin 16 battery positive).

The question is if this data signal wire is present on the Australian delivered cars or not, and if the functionality is enabled in the ECU.

When time permits I'll look into this, and if the wires are there I may raid a car at the wreckers for an OBD2 plug!

Has anyone else ventured down this path?

Cheers

almost certain that our ECUs are differ from USDM cars - ours won't have the ISO 9141 serial port.

VERY happy to be proven wrong though!

I've thought about this over the years but i don't think i'm technically skilled enough to work it out, let us know how you go.

I tried a diagnosis - odbII adaptor without any success.

Not saying it won't work, but don't think we got all the sensors, so you may not achieve full functionality.

Locutus wrote:almost certain that our ECUs are differ from USDM cars - ours won't have the ISO 9141 serial port.

From pics, I don't believe our NB8A ECUs differ externally from the USDM ones, & again from pics, I don't believe the USDM NB8A ECUs have an ISO 9141 serial port.

There's a pin present in the right location of the diagnostic connector on my car:



I haven't had time to check the ECU end.

Pic of inside of ADM NB8A ECU courtesy of Matty:

viewtopic.php?f=55&t=38325&p=498641#p498641

Thanks 93_Clubman but unfortunately you can't really see what 1D is doing from that picture.

Just out of interest this is a pic of the top side of my ECU:
http://farm8.staticflickr.com/7256/7641965824_06317113b0_k.jpg

Too bad I hadn't taken pics of the under side!

I'm just going to try it and see. Car raided:



I will temporarily hook it up via the diagnostics connector and see if the ECU spits out any data to a ScanGauge.

VERY keen to see how you go.

Close, but no cigar:





Looks like the protocol isn't compatible. I've othered another cable so I can do some prodding via PC.

For those playing at home, this is the cable I had from Mazda - ODBII which didn't work for me either.

http://www.pixelculture.com/ODBII-Mazda_cable_2.jpg

If you really want OBDII, why not just reto-fit an NB8B ecu? Only difference (as far as the ECU is concerned) would be the VVT control(?), and that should be fixable. Might need to get keys and ignition lock too, to match the ecu.

If you really want OBDII, why not just reto-fit an NB8B ecu? Only difference (as far as the ECU is concerned) would be the VVT control(?), and that should be fixable. Might need to get keys and ignition lock too, to match the ecu.

Hey all,

I was just about to start a topic on this, but found this thread.

My NB8B "SP" from all search details, doesn't have a OBD2 port. From information I have obtained, they came in 2003 with the introduction of the NB8C.

1) Is this correct, If so where is it located?

2)if incorrect, can I retrofit the plug into my NB8B ECU?

Thanks, I did find that thread, its all a bit to much for my brain.

Any idea if I can fit one still?

Also.. aftermarket ECU systems don't use obd2, correct? Is there any that engine diagnostics can be measured from?