dashboard wires go where?
Discussion
Where do the dashboard instruments get their power and earth from?
The voltmeter has started dipping wildly when I turn on small loads like indicators and brake lights, and I'm trying I'm trying to work out why. With everything on it goes as low as 9v which is clearly wrong! I'm pretty sure it's a wiring fault but so far I can't see where the instruments get power *or* earth supplies which is making it a bit difficult to track down. I've got my eyes on that big 20-way connector down by the ECU, am I on the right tracks?
I've looked for an earth on the passenger side outrigger (there is one, and it's fine, but the instruments don't earth through it) and under the tunnel (there's a body mounting bolt, but no connections to it). There must be a chassis earth somewhere under the dash, any idea where?
BTW I've confirmed the battery voltage is fine, the feed out of the ignition switch is fine (dips a little under load but nothing like the dip shown at the voltmeter), all the fuses are OK, no obviously broken wires in the mess of wires in the passengers footwell(I'll resist the temptation to call it a 'loom'). I haven't tried pulling fuses and connectors apart to see which one feeds the dashboard, but I guess that might be the next step.
On the bright side, while I was looking into this the intermittant fuel pump problem I've been trying to track down over the last few weeks finally showed up enough for me to track it down with a meter. It seems that I have an intermittant break in the wire from the fuel pump relay to the pump. It's going to be a pain to replace, but at least I know what the problem is now! As far as I can tell, this isn't related to the voltmeter problem though.
So, instrument power and earth, any ideas where they come from?
Thanks for any help.
Cheers,
Peter Humphries (and a green V8S)
The voltmeter has started dipping wildly when I turn on small loads like indicators and brake lights, and I'm trying I'm trying to work out why. With everything on it goes as low as 9v which is clearly wrong! I'm pretty sure it's a wiring fault but so far I can't see where the instruments get power *or* earth supplies which is making it a bit difficult to track down. I've got my eyes on that big 20-way connector down by the ECU, am I on the right tracks?
I've looked for an earth on the passenger side outrigger (there is one, and it's fine, but the instruments don't earth through it) and under the tunnel (there's a body mounting bolt, but no connections to it). There must be a chassis earth somewhere under the dash, any idea where?
BTW I've confirmed the battery voltage is fine, the feed out of the ignition switch is fine (dips a little under load but nothing like the dip shown at the voltmeter), all the fuses are OK, no obviously broken wires in the mess of wires in the passengers footwell(I'll resist the temptation to call it a 'loom'). I haven't tried pulling fuses and connectors apart to see which one feeds the dashboard, but I guess that might be the next step.
On the bright side, while I was looking into this the intermittant fuel pump problem I've been trying to track down over the last few weeks finally showed up enough for me to track it down with a meter. It seems that I have an intermittant break in the wire from the fuel pump relay to the pump. It's going to be a pain to replace, but at least I know what the problem is now! As far as I can tell, this isn't related to the voltmeter problem though.
So, instrument power and earth, any ideas where they come from?
Thanks for any help.
Cheers,
Peter Humphries (and a green V8S)
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