Loss of ignition lights

Technical Area Electrics & ICE
1
  1. My model of MX-5 is: __MK2
  2. I’m based near: Wimborne__
  3. I’m looking for technical help or recommendations on: ignition fault

Previous owner/s have had fitted professionally a push button start in place of the cigarette lighter. Over the past six months or so and intermittently on turning the key to just before the start I have no ignition lights, nothing. Removing, refitting and turning the ignition key sometimes would jolt the lights to show and allow a start, but over a period of time this has become worse and no matter what I did a no show of lights thus no start. Oddly enough and without the lights I could press the start button and there is power to turn the starter but due to no lights, no start. I found that disconnecting the ignition from the back of the key barrel and using a dumpy screwdriver in the slot, a start would always occur. The key way in the barrel is intact. I changed the ignition unit but the fault would at some point re - appear, normally at an embarrassing time. In the end and as it is now I have disconnected all and resorted to the normal practice of a key start and to date, which is some six to eight weeks, I have no start problems. I have had the circuits checked by an Auto electrician and nothing shows up, mystified. OK some will say forget all and carry on using the key but with the push start button fitted I want to use it but dare not. Any pointers will be appreciated. To my mind do I have a discharge to earth somewhere? Could it be the start button? though with its simplicity how and what?

2

The barrel only operates the ignition switch, which you say works with a dumpy screwdriver.
So for me one of two things is hapenning.
Either the ignition key is not turning enough (maybe the key slot in the switch is worn)
or
There’s a loose wire somewhere, and dropping the switch off the back of the barrel is enough to make that wire contact.

Ideally a wiring diagram would help.

3

Hi there thank you for responding. I can state that the key within the barrel turns the necessary rotation, there is no problem there. This fault has no set timing or doing something which would set it off again. After removing and replacing the ignition unit all will be normal again for some time then disaster it happens, no ignition lights no start via the push button start. Remove ignition switch hey presto, dumpy screwdriver to the rescue, all lights, push button start OK. I am now pretty swift with removing ignition switches under dash along with the small retaining screw. A comment from the auto electrician suggested overkill with all the connections in association with the fitting of the push button start, along with a relay but did not clarify because all was working as it should, typical.
My thought is to find a wiring diagram for the fitting of a “Push button start” and see just how mine corresponds or not as the case may be. Any pointers for where I can find a wiring diagram?
As I mentioned I am using the key start and all is fine, touch wood.