hi,
first a minor confession, the question is for a Westfield kitcar with mx5 running gear -however the mx5 was one I owned, ran, loved, the bodywork was nrt h ot going to make another mot, so the car will hopefully live on another way- thought I best explain hence the odd question.
I’m following the wiring diagram for the 1997 1.8manual uk mx5 via the Mitchell repair pdf that is around a few places online. Its been great for 99% of stuff however the wiring for the black instrument connector is very different for example there is no impbiliser mentioned.
where I’m struggling is the engine check light signal. Yellow/black from the diagram, but not the case for me. And the instrument cluster itself is long gone, just left with the connectors 
ried tracing back to the ecu but wiring appears to differ here too!
any thoughts on the ecu check light on such a car, or a wiring diag that reflects the car?
Struggling to find an accurate diagram,but what colour wire do you have at pin #2 at the ecu multi plug.
Hi,
Id need to check the wire colours, but they’re certainly different to the diagram I have!
After a dig on the MX5 diagnostic port pins I stumbled across this http://www.mazda-madness.co.uk/2010/03/diagnostics-for-the-eunos/
which says…
“The Eunos MX5′s diagnostic system isn’t connected to the Engine Check Light on the dashboard”
So maybe I’m looking for a ECU --> instrument cluster wire for the “check engine” light that doesn’t exist!
I need to have a play with the diag port and see what I find
Unfortunately my 1997 MK1 is a 1.6 so there would be some differences but if you have some straightforward questions I may be able to assist as the clam shell trim is off my steering at the moment.
Anyone around you got a UK spec MK1 - anything from 1995 on should have the same factory immobiliser setup.
There is no check engine light on a 1997 UK car.
Thanks for the replies. That is the conclusion I’m rapidly coming to…
Does anyone know if I can wire on up!? I’ve some spare ignition switched live feeds in the loom, and could splice into the “FEN” (Faults Engine?) wire that goes to the diagnostic port…
From some wiring diagrams this appears to be how some of the cars with instrument cluster “check engine” lights are wired - does make me wonder if these are OBDII cars though (mine isn’t)
Hi,
So I’ve spliced the wire that goes to the FEN (fault codes engine) in the Diag port, as far as I can see this provides the functionality of the ECU check light that is on the dash of some cars, I’ve hooked this up to an “ECU” LED for the dash.
The only caveat is that I need the TEN (Test Engine) grounded in the diag port to have the LED in “test Engine” mode.
So I’m considering leaving TEN and GND connected in the diag port - does anyone see an issue here? Presumably this just dictates what the diag port does, not make the car run on limp home mode etc?
I think you will find that the check engine or mil lamp is not connected to the diagnostic port on any car.What you effectively doing is putting the engine ecu into test mode to flash an led.This is the blink code system that most Jap cars used before the introduction of the obd 16 pin system
Yes misfire is right and this applies to all MK1 and MK2 cars with the diagnostic socket.
I am going to wire up an in car test circuit for my MK1. This would involve a switched link between TEN and GND and between FEN and +b where there would be also be an LED. All the switching and LED would be in the car. Not sure if the link between FEN and +b would necessarily need to be switched - must check this out. A lazy man’s diagnostic check:-)
Yes misfire, so we’re achieving the same thing. you’re looking at an LED, me an LED with ECU written on it 
You talking of having an in cockpit switch for connecting TEN and GND - me, considering a join in the diag port of those same pins, so it’s constantly in diag “test engine” mode - what I don’t know is whether this just dictates what the diag port does, or if its effects are wider and changes he way the car runs (lean, rich, limp home etc)
TEN GND put the car is base setting mode, you bridge them to adjust the idle speed and ignition timing. On some models it also activates the switch test so the fan will come one when certain switches are operated.