MX5 diagnostic "tool"

[A2Z]

Hi All,

The "diagnostic tool" for reading fault codes.....the LED, resistor and paper clip solder job. Is it supposed to work on a late model (after 95) MK1? I have the instructions and made on up. I have read conflicting stories about it working/not working on cars after 95 (something about changing to OBDII). Doesn't work on my 97, not even a flicker. Is it worth me blowing a whole 79p again in Maplin to buy duplicate parts in case one was faulty?

[Gizmo!]

Must pay attention to this... wonder if it can tell me why mine isn't working

[A2Z]

Anyone?

I'll make a duplicate "tool" but will I be wasting my time?

[Richyvrlimited]

A2Z said:

Anyone?

I'll make a duplicate "tool" but will I be wasting my time?

Should still work UK/JDM cars didn't get OBDII till the MK2.

Are you sure you have the LED the right way around, they only work one way

[A2Z]

Richyvrlimited said:

Should still work UK/JDM cars didn't get OBDII till the MK2.

Are you sure you have the LED the right way around, they only work one way

Actually, No, I'm not sure. I didn't realise it was an issue. The instructions I downloaded off the OC website didn't mention it, just solder a resiator to one of the LED leads.

I'll swap it around and take another go. Thanks.

[Mazdamender]

Should work up until the Mk 2 2000 model,but some flash codes will be different.
OBD II was 2001 >
This may help?....
http://www.mx5oc.co.uk/forum/forums/t/204.aspx
M-m

[A2Z]

Mazdamender said:

Should work up until the Mk 2 2000 model,but some flash codes will be different.
OBD II was 2001 >
This may help?....
http://www.mx5oc.co.uk/forum/forums/t/204.aspx
M-m

Thanks everyone. I got it to work, well the test flash did, it didn't flash any codes to me. I disconnected the battery last night to clear them, took it for a drive this morning and I didn't get any faults, which leads me to believe that the rough idle is coil pack rather than O2 sensor related, but that is another story....

Anyway, for future reference.

I used the guide above to do this which has been lifted pretty much word for word from the guide on Miata.net. Neither mention that the LED can be the wrong way round, in fact it states "it doesn't matter which side of the diode you put the resitor on"!! Oh, and this guide mentions that it may not work on post '95 cars. It works on my '97 MK1.

I bought a new diode and resitor just in case (68p from Maplin) and wired it differently to my last attempt using this guide....

http://www.kpsec.freeuk.com/components/led.htm

Basically one wire of the LED will be longer than the other, put the resistor on this one. There is also a flat spot on the diode "collar", put the resistor on the lead OPPOSITE this flat spot.

Wire it in with the bent paper clip as well as per the guide and you get a 4 second constant flash as a test, it should then flash codes to you (if you have any).

Thanks again everyone.

[franv8]

Just to make things a little neater, you can just be 12V LED's from Maplin, so no need for the resistor. (Obviously buy the small ones - you don't want to overload the ECU..)

[Richyvrlimited]

A2Z said:

Thanks everyone. I got it to work, well the test flash did, it didn't flash any codes to me. I disconnected the battery last night to clear them, took it for a drive this morning and I didn't get any faults, which leads me to believe that the rough idle is coil pack rather than O2 sensor related, but that is another story....

Anyway, for future reference.

I used the guide above to do this which has been lifted pretty much word for word from the guide on Miata.net. Neither mention that the LED can be the wrong way round, in fact it states "it doesn't matter which side of the diode you put the resitor on"!! Oh, and this guide mentions that it may not work on post '95 cars. It works on my '97 MK1.

I bought a new diode and resitor just in case (68p from Maplin) and wired it differently to my last attempt using this guide....

http://www.kpsec.freeuk.com/components/led.htm

Basically one wire of the LED will be longer than the other, put the resistor on this one. There is also a flat spot on the diode "collar", put the resistor on the lead OPPOSITE this flat spot.

Wire it in with the bent paper clip as well as per the guide and you get a 4 second constant flash as a test, it should then flash codes to you (if you have any).

Thanks again everyone.

You misunderstood me. The side the resistor goes on is irellevant, it's merely there to stop the LED (Light Emmiting Diode - and Diodes are a bit like a 1 way valve for electricity), from blowing.

As LED's only work one way around, you need to ensure you put it in the diagnostic socket the correct way around - putting it the wrong way around won't break it, but it won't light up.

[A2Z]

Thanks,

I had tried all ways to get it to work, resistor side to B+ etc. Maybe something was faulty as it works now.