1800E Electrical shenanigans.

[sleek lemur]

Weird one this time.

I've had the over-reading water temp gauge issue. Changed the VStab and seemed to make a little difference, but gauge still reads close to read. Engine obviously not overheating and testing temp with laser thermometer shows good readings. So I got used to an over reading water temp gauge.

Driving this evening, stopped for fuel. Setting off, I noticed the water temp gauge was reading correctly, or between the two markers, about 1/3 up the dial. But then I saw the red IGN light glowing gently (not fully lit).
Pulled over to check alternator. Nothing seems loose. Continued on, but then I realised that when I operate the turn signal, the red IGN light lights fully. Turn signals do not work. Hazards work fine. Got home ok. Now when I turn on the ignition, the IGN light does not shine, but when I start the car, the IGN light shines brightly. Water temp gauge now inoperative. Fuel gauge shows 1/4 full, but tank is full. Still no turn signals. Hazards ok.

I'll take a look in the morning, but in the meantime, any ideas on where on earth to start ?

Sigh.......

[Ron Kwas]

SL;

Without looking at Wiring Diagram more specifically to find which fuse is involved, it sounds like the Ign power fuse involved with instruments is either blown open or has poor connections...I'd clean all fuses and reinstall with ACZP, and see if symptoms remain.

Good Hunting

[142 Guy]

I assume your reference to the IGN light is the charge light on the dash.

With the engine running, use a voltmeter to check the voltage at the battery + terminal. If it is running around 13.8 - 14.2 volts then the alternator would appear to be functioning correctly. This would be a little odd because for the alternator to function it normally has to get a field flashing current through the charge light; however, sometimes there is enough residual magnetism in the field for it to boot-strap itself and start working.

The fact that your cluster now appears to be 'mostly dead' and that the charge light shines brightly when the engine is running suggests that the alternator is probably functioning; but, you have a short circuit to ground somewhere on the 12 volt supply to the instrument cluster.

[sleek lemur]

Thanks to Ron (again!) & 142 for useful hints.

Fuse 4 (indicators and dashboard gauges) was blown. Restoring that got rid of the weird stuff with the IGN light.

As for cause, I found loose earths behind tacho and fuel gauge. A loose earth caused the power line to my electric fan the burn out a while ago, so I'm hopeful this is it. I did have the horn shorting out against the body last week, but that's a different fuse. A lot of wires to look at, so any particular suggestions gratefully received.

In the meantime, thanks again!

[Ron Kwas]

SL;

...good to hear, that I had the symptom/cause right,but note that "looseness" of a wire alone will not draw a fault current and blow a fuse...unless live wires are so loose that the touch chassis...

When a fuse blows, its always preferrable to track this down to a specific cause of the over-current, so that it can be properly sorted...otherwise the issues can return at an inopportune moment (thanks to Murphy)...

Cheers

[sleek lemur]

Wise words Ron. But aside from eyeballing the under- dash wires ) especially the stuff I've been messing with), I don't know what more I can do now that everything is behaving itself.

I have about a thousand miles of holiday driving planned for the next month, so no doubt I will be presented with some "inopportune moments"!

[sleek lemur]

Hi again😥. Car all fine yesterday, but went to drive today and no ignition supply at all. Battery fully charged. No blown fuses. Lights, hazards work fine, but when I turn the key to get IGN, nothing. No IGN light on the dash and no indicators, wipers, heater blower etc. Obviously no power going to starter motor either.

Wiring diagram I have is difficult to read. I seem to have power at the ignition switch on the red lead. Not sure what I should be testing otherwise.

Thanks in advance....🤯

[Ron Kwas]

SL;

General suggestion is to clean all main power wiring to shiny and reconnect and tighten. Specifically Batt/ Starter heavy cables, chassis ground strap, Ign Sw cables...AT LEAST! If Batt is fully charged, and connections are without issue, Starter should at least give signs of life!...if not, locate interruption of power...!

Good Hunting!

[sleek lemur]

Thanks Ron, battery 100% charged. Managed to get the car going again after messing with he fusebox, but to be honest, I still don't know what the problem was.

You're right. I need to clean the whole lot.

[Ron Kwas]

SL;

If you're just "messing with" electrical connections and components, I expect it will take you a long time to locate the root cause...if ever! Successful troubleshooting takes careful observation of the symptoms, association the failure with special conditions, if any, maybe some measurement or tests, and deduction of the situation given these conditions...that's what I'd suggest...in the end, you'll find there is very little magic or voodoo happening...it just might seem that way at the beginning of the process...

Good Hunting!