Main Beam Dash Bulb

[Shane]

Thanks Guys,

I have unplugged both headlights and the needle doesnt jump when the main beam is flashed.

Also i have checked the grounds, wire brushed paint and bolted them on then sprayed with lacquer to protect, also checked resistance from headlight to ground point and seems ok (0.007)

To confirm, When the fan kicks in the temp gauge jumps off the gauge Hot, not slowly, but like it's been switched on.

[Stiggy]

Lets get back to basics, if any one of your electrical items does not have a proper earth it will find a path if it can via something else.
The big question is, if it worked in the MX5 why does it not work now? Something changed along the way, we just don't get electrical issues with Exocet.


upload image websites

[Shane]

Thanks Stiggy I couldn't confirm if that worked in the donor or not, flashing the headlights and watching the bulb and temp gauge needle on the dash was the last thing I was checking

My gut feeling is that it is an earth issue, but how the hell can I found out what and where the problem is

Everything else is working perfectly, no dimming lights etc, just the dim main beam bulb in the cluster and the jumping/reading hot temp gauge

[gwnwar]

IF you unplug the connectors one at a time from the ECU/PCM what happens.
Is the jumping with key on or off or both.. engine running or off or both..
3 systems make it jump. lamp flash, coolant fan on, reving the engine. Right any thing else??
This is starting to hurt the brain..

[snowbird1]

I agree that it seems to be a ground problem, from the circuit diagram it looks like the instrument pack and headlight switch share a ground.

Using a DVOM to check ground continuity can be misleading – the DVOM uses a very small current to measure resistance, this is good when checking electronic circuits but not when checking power circuits.

A better way to check integrity of power circuits is to check voltage drop. To do this, set the DVOM to the low volt setting, connect one lead to a good ground, preferably the battery negative terminal and the other lead to the ground terminal of the component being tested. With the circuit inactive the reading will be zero, when the circuit is actuated you will see a voltage, anything over about 0.1 volt indicates a high resistance in the circuit. You can then work back to the ground to find the problem.

[Shane]

Im going to run a wire from the negative battery terminal to each of the ground points one by one, to rule out the physical location of the grounds.

I will also check the continuity of the ground wires to see if there are any breaks specifically in the multi block which has the cluster and headlamp grounds connected.

Be back asap

[Shane]

Ok, so had a good day on the car today.

I have found that the ground from the battery to the ground points are not the best, although the resistance on the multimeter shows roughly 0.8 (which I though was fine) when I connect a wire from the battery negative straight to the earth point for the cluster it holds the temp gauge down alot more and doesn't jump as much when the main beam is flashed it only wobbles slightly, so I have order a 4awg cable to add a good ground to the chassis as I only had a 2mm cable to hand to test with so hopefully a 4awg will provide an even better ground. I have further reduced this issue by wiring in a 12v bulb between the pink cable behind the cluster that controls the temp gauge basically this reduces the ground even further which in turn keeps it under control even more, to the point where it's barely noticeable and the gauge reads correctly (50%-60% swing when hot) and doesn't spike off the gauge when the fan kicks in or when I flash the headlights!

I have worked around the main beam bulb on the dash by wiring in a new led bulb by connecting to the headlight main beam cable (red/black). By pushing the led further into the cluster it's a bright as day!

Neither of these are fixes and there is still and underlying issue but no one apart from me and this forum would know. So I'm happy to have even got to this point which I couldn't have done without you all especially George (gwnwar)

Still open to any suggestions but as it stands I'm happy!