The 'E' Type Forum

Just been out for a quick spin in the afternoon sunshine, and noticed after about half an hour that the fuel guage was doing all sort of weird and wonderful things, going from empty to full, then back again; up and down.

The tank is full by the way!

Anyhow, came home and reversed into the garage to notice that ALL the guages on the centre fascia are all dead.

Very odd. Everything works, no issues with the car running and the fuses are all sound.

Any ideas? Would the voltage regulator do this if it was "iffy"? (I know theyre notorious!)

advice appreciated in advance

thanks

Paul

The VR only affects the fuel gauge and the temperature gauge.

Hi Paul......looking at the wireing diagram all the gauges connect to the voltage regulator and the regulator gets its feed from fuse 6......so the only common point for all gauges is the single Green wire from the VR to the fuse or the fuse......try cleaning the ends of the fuse and the springs it locates in.....Steve

As Steve mentioned it's probably the fuse, although I think it's fuse 7 for the feed to the voltage regulator. Fuse 7 also supplies the wipers and rev counter so easy to check

Yes its fuse 7 following those little lines on the wireing diagraw is a nightmare......whilst your at it clean up all the fuses and contacts and spray over a lightly with wd40 to keep moisture at bay......good lock Steve

mgcjag wrote:Hi Paul......looking at the wireing diagram all the gauges connect to the voltage regulator and the regulator gets its feed from fuse 6......so the only common point for all gauges is the single Green wire from the VR to the fuse or the fuse......try cleaning the ends of the fuse and the springs it locates in.....Steve

Not quite true. Only the fuel and water gauges get the regulated 10v off Green/Black, the other two take their feed from the 12v Green input to the VR. If fuse 7 has gone the instruments would stop working but so would the reversing lights, tachometer and choke warning light:

If the VR was dodgy then I would expect the water temp gauge to jump around just as much as the fuel gauge, given that they take the same feed from the VR.

What about a dodgy fuel sender, on it's last legs. That might explain the wild readings. But doesn't explain all the dead gauges at end of trip.

Hmm, maybe it's a combo. VR and/or fuel sender and/or fuses.

Or the failing fuel sender (wild display) finally failed and caused a short circuit that popped fuse 7.

Hi

When this happened to me it was the sender - corrosion on the copper wire caused erroneous readings. Took out the sender, dismantled, cleaned and AOK.

Ian
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The only single thing I can think of that would do that is that there is no earth to the fascia plate. This would be highly unlikely to occur as it's earthed in several places, but easy enough to check.

Thanks for the replies thus far chaps.

Just a quick thought I had overnight...... dont they share a common earth?.

if so, that could be the problem? Isnt the whole rear of the panel earthed?

I may be wrong but I don't think a common earth would be the issue stopping all the gauges working: the battery gauge has a dedicated earth lead from the loom and takes it's power directly from the VR 12v green supply (which is directly from the Fuse box).

Others might know but the other gauges appear to operate just from the current flowing through them and therefore can operate in isolation.

Whether an earth caused the initial problem I'm not sure. Have any of the other components off the fuse also stopped working? Otherwise a multi-meter would help trace the problem.

Also the Wiper Switch shares the same earth. So if this works, your issue with the gauges is not due to the earth cable.

I also had an issue with my gauges and I made a few tests yesterday to find a way to solve this. It's easy to identify the green feed which runs from the fuse n?7 to the voltage regulator. Disconnect the other cables on the volt. reg., to check only the battery gauge. Don't forget it takes a few seconds to the hand of the gauge to move... If this work, then connect the cable from the voltage regulator to the oil gauge. Etc..

p.s. Is it possible to check the battery gauge without passing trough the voltage regulator?

The battery gauge must not go through the VR otherwise it will only register 10v. The voltage regulator does just as its name implies - it sends 10v to the fuel and temp gauges regardless of what the battery voltage is, which could be anything from 11v to 14v depending on state of charge. Otherwise they would misread.

Hi all

Just come in from the garage and it's all solved...........

As usual it's the simple things.......

The green power cable from fuse 7 wasn't actually connected into the fuse board. The previous owner had jammed the spade between two others rather than connect to a tab!

It had rattled itself loose, hence the wayward Guage as it lost power then restored as it jumped around.

Connected it to one of the rear spade tabs (small hands are useful sometimes!) and all is good with the world again.

Many thanks for the input and apologies for taxing all your grey stuff... It looked fine in there; the wire problem only became clear once I went in and gave each of them a tug!

Cheers all.