Mx5 NB (1998) voltage problem using Diagnostic

[jonathan.miata]

Hi,

I'm a new owner of an NB mx5 but I'm having two problems that may or may not be linked;

I'm unable to use the Diagnostic tool to read an engine check light code, when I use a Multi-meter in the ports its seems the voltage is low ~1V and fluctuates.
I've checked my LED works when connected directly to the 12V battery so does anyone know what could cause this problem?

My other problem is a severe batter drain that almost stops the car starting in 2 days from a fully charged battery, I have cleaned the battery terminals and have read more than a few articles on this so I guess I'll be pulling fuses tomorrow night however I thought I'd ask if anyone had the combination of these two problems before or am I just lucky?

Jon

[hobobaggins]

hi, start by looking for an aftermarket alarm or an extra wired in foglamp if it's an import, as they are common drains.

[jonathan.miata]

Thanks for the reply, I'll try pulling those fuses first and see if that fixes the problem.

On the first question I asked, I just realized that it wasn't actually the check engine light on, it was the brake light so I'll try just topping up the brake fluid (face palm), although I don't know why I could n't get the diagnostic LED to work...

[hobobaggins]

Ah that will make your life easier! The drain should be something obvious, anything aftermarket, if it has a boot interior light pull the bulb etc. Just keep trying until it stops draining, also might be worth checking that the battery itself is in good condition or if it's garaged getting a trickle charger.

[MX-5 Lazza]

Have you checked the passenger footwell for damp? If the ecu gets wet it could cause both of those issues.
And what battery do you have?

[jonathan.miata]

This is the level of brake fluid required to trigger the brake warning light, my bank account is lower than this level!
Atleast it was an easy fix, now onto diagnosing the battery drain...

[jonathan.miata]

I just saw your message lazza, I'll take a look at the carpet.
The battery us brand new as that was the first thing I looked at.
The previous owner did two things recently, changed the rear light and disconnected the aerial so I'll poke around there and let you know what I find...
I knew buying a 1998 mx5 would be an adventure but I enjoy the fun of DIY!

[MX-5 Lazza]

It's under the carpet you need to check

[jonathan.miata]

So I removed the fuses to the radio and cleaned the contacts of the ECU connectors, that looks to have stopped the battery drain.

However I have a problem starting the car when hot so it looks like I need to buy some CAM sensor....
Soon I might be able to enjoy driving the car!