Petrol 2.0l 2002 OBD and readers/volt meter (engine check light on)

[IanMc]

Hi all - I've just got my first Bongo and re-assuring myself all is in order, starting with a basic service and cam belt. Servicing was all straightforward, but just before I got the spanners out, the engine check light came on. I thought I would do the service before looking into that. Once I had done the cam belt, reconnected the battery and restarted the light was out (hurrah!), but once I had changed the plugs and re-started, light back on (bugger), so I am assuming disconnecting the battery reset the system but was then re-triggered. I have trawled the forum and factsheets for OBD access info. I understand the 'hot wiring' approach, but i) I seem to have a pin set up which is unusual and I don't want to short something expensive out and ii) the factsheet says you have to use a voltmeter rather than a bulb, but I am not sure how that translates to the coding - I assume you have to use an analogue display type and count the pulses?

I can't upload a pic of the OBD, so to describe it: top row is 2 groups of 2 terminals (first one empty in first group), second row of 7 terminals (last 3 empty), third row of 6 terminals (last 3 empty), fourth row of 6 terminals (terminals 4 and 6 empty). Hope that's clear. The factsheet says TEN to GND which I think is third terminal on top row and first terminal on the second (OK), then a voltmeter between +B and FEN which is fourth terminal on the top row and the *missing* first terminal on the first row (not OK!). Do I simply use the MEN terminal next to it or is it more complicated?

There are a few promising conversations about using Forscan or Autel readers, but still require some hot wiring. Did anyone come up with an adaptor for this or is hotwiring unavoidable given the number of variations in the OBD layouts? In this discussion, I can see they use the MEN terminal

So, I'd appreciate any advice on which terminals to use and what sort of voltmeter (and what to count). Ideally, I would hook up a reader if there is a known combination that works out there.

Incidentally, I noticed in the various OBD discussions for engine faults, it always seems to end up with the lambda sensor... as they are quite pricey, I'd like to be sure first though! I should have said at the start - it appears to be running fine, but the check light is on.

[g8dhe]

The OBD connections differ with the number of pins actually fitted depending on what ECU version suggest you read the factsheet and also this site http://www.philmcfadden.co.uk/MazdaDiagnosticBox.htm no one to my knowledge has constructed a readout box or similar as the main problem is the error codes not all being known, early versions were just two digits later versions are 4 digit and correspond with the OBDII error codes which can be found using google with "mazda error codes Pxxxx" as the search terms.

[IanMc]

Hi Geoff - thanks for responding. I have read the factsheet and now that website. Both assume there is a FEN terminal, and mine does not appear to have one. I know one of them must be the the FEN because the check light is on, so a fault code has been sent somehow - unless the OBD is a red herring and the check light means something else with some models? I'm none the wiser on how to use a voltmeter (factsheet says only this for petrol versions) or what type either.

[g8dhe]

With a 2002 model just check that you aren't actually on an OBDII ecu, if so there will be an added OBDII socket on the underneaath of the console to the left of the steering wheel;

[IanMc]

Hey, it's there! I did see a reference this in a post, but I thought it was in the engine bay somewhere, so assumed it wasn't there. I can now see it tucked up under the dash. Rhetorical question for Mazda: why leave the redundant OBD plug in place to confuse matters? So, OBDII reader on order and hope to get the code off and the right part ordered. I will post back with results. Thanks, that tip may have just saved me a lot of hassle!

[g8dhe]

No, all OBDII sockets have to be within a certain distance of the steering wheel and controls so that you can plug in and then operate the vehicle and see the test set at the same time - a very sensible idea!

The OBD socket isn't redundant as there are some operations that have to be enabled with links etc. like fuel pump and so on that the OBDII standard doesn't allow for.

[IanMc]

Epilogue! After waiting an age for the reader to arrive, I plugged it in and it found a code, but could not read it! ('No codes stored in the module'). I saw the advice on getting a good quality reader, but I don't know how you know that other than price. The one I got was £15 so I was not sure if the reader or the module is at fault, but assumed the reader was not up to it. Reading the various threads on 2.0ls, it seems that most people, after spending a lot of time on readers end up with the same fault, ie. the lambda sensor, so I thought I would take a stab and change that. Rapidair recommended the DOX 0109 universal which is against the factsheet advice, but his has lasted 2 years already and at a 5th the cost of the original, I thought it was worth a shot! 24 hours later, all is well.

On the universal sensor, it's really easy to do, and even easier than others have reported if you fit it in situ, ie. splice in the new sensor without trying to undo the super fiddly connection block over the gearbox. It also means you don't have to splash out on a specialist removing tool, as you can just cut the cable and use a ring spanner.

In a quiet moment, I will try 'hotwiring' the reader to the original Mazda OBD block as per the forscan website and see if I get any more joy that way. Interesting point about the OBD2 plug not covering all the options alone. Does anyone have a reader that has proved to be of the 'right' quality?

Thanks everyone!

[Bob]

Very useful update, thanks.