Electrical Stuff

[GOG440]

I have a few electrical issues with mine most of which I think are to do with a bad earth from the dashboard.
Before I start laying upside down in the footwell does anyone know where the earth lead on an 87 350 should be?

For info the issues I have are:-

Oil pressure gauge goes to max as soon as engine fires up.
Temperature gauge u/s
Fuel gauge useless (empty all the time) except if i put the handbrake on. Then it goes to max.

All the lights/horn/stereo work ok, only other thing that doesnt work is my electric window,and I think that is because of a broken wire.

[jindle]

Still need to sort the same thing out on my 85.

I had a look up behind the fuse panel/relay board and there were a earth points everywhere, there is definitely one just on the far right (if you're upside down) towards the wing, and a number of wedges have an earth running through the bonnet release cable.

there are probably then a number of bodges stereo/centre console.

good luck!

[gmw9666]

GOG440 said:

I have a few electrical issues with mine most of which I think are to do with a bad earth from the dashboard.
Before I start laying upside down in the footwell does anyone know where the earth lead on an 87 350 should be?

For info the issues I have are:-

Oil pressure gauge goes to max as soon as engine fires up.
Temperature gauge u/s
Fuel gauge useless (empty all the time) except if i put the handbrake on. Then it goes to max.

All the lights/horn/stereo work ok, only other thing that doesnt work is my electric window,and I think that is because of a broken wire.

Will be watching this with interest, Snap!

[ElvisWedgely]

Wedges come standard with electrical issues. From what you describe I think each case is a separate problem. It is a fiberglass car hence everything is individually earted. The main earth as far as I'm aware is from the battery negative down to the chassis. It is important that this earth is making good contact. From there you have to tackle each case individually. It could be faulty gauges or faulty sender or sensors or bad earth of each separate item. You have to use elimination and fix each one as you go along. The electric window could be a broken wire, faulty switch, faulty motor, jammed accumulator or runners or even bad earth. It could also be that in it's lifetime the car may have been fitted with total closure system and now is intefereing with it's function. So elimination is the key, and plenty of man hours. Good luck.

Tony. TCB.

[GOG440]

ElvisWedgely said:

Wedges come standard with electrical issues. From what you describe I think each case is a separate problem. It is a fiberglass car hence everything is individually earted. The main earth as far as I'm aware is from the battery negative down to the chassis. It is important that this earth is making good contact. From there you have to tackle each case individually. It could be faulty gauges or faulty sender or sensors or bad earth of each separate item. You have to use elimination and fix each one as you go along. The electric window could be a broken wire, faulty switch, faulty motor, jammed accumulator or runners or even bad earth. It could also be that in it's lifetime the car may have been fitted with total closure system and now is intefereing with it's function. So elimination is the key, and plenty of man hours. Good luck.

Tony. TCB.

Bugger

I was hoping that there was a common earth for all the dashboard issues.

Out with the multimeter then.

[jindle]

also, if you figure out a good way of sitting in the car upside down please let me know. i've got this scheduled for sunday (weather permitting).

[GV]

What I did was to re-connect the live feed to each of the gauges to a reliable ignition feed. I then did the same with the the earth to a reliable earth feed via the negative earth from the the battery. I also wired in my gauge lights the same way - so far no issues and everything works reliably. The sender feeds all had new terminals at both ends too..

[RCK974X]

I investigated my Series 1 and the dash instrument earths are 'daisy chained' back to a single wire, and it's not at all obvious where it goes back to real earth, as it's part of main loom. I did because fuel guage stopped working, and then fuses started to blow.

Blown fuses turned out to be REALLY bad insulation, live soldered joins with only insulation tape (don't know if that was original or not)

Fuel guage turned out to be the sender, after a lot of wasted time.

(mine is one of those wired all in black - it's a future job to rewire it....)

[Jack Valiant]

Easiest method I use is just make up a couple single core leads with small electronic croc plugs on each end. Connect to the battery neg post and then jump to all the neg sides of the item not working...... Simples

Chris

[adam quantrill]

The earthing for the dash goes through the bonnet pull cable. This is highly unreliable and being steel tends to corrode.

So run an earth strap from the rear of the engine where the battery strap is, through the bulkhead grommet, to the bonnet pull end in the cockpit - you'll see a metal bracket up to the dash.

That should help with stuff like when you put the fans on, the battery voltage droops, and also it flickers with the indicator, or door open, etc...

reminds me I should do this on the 400SX (done on the 350i ages ago).

[RCK974X]

adam quantrill said:

The earthing for the dash goes through the bonnet pull cable. This is highly unreliable and being steel tends to corrode.

So run an earth strap from the rear of the engine where the battery strap is, through the bulkhead grommet, to the bonnet pull end in the cockpit - you'll see a metal bracket up to the dash.

That should help with stuff like when you put the fans on, the battery voltage droops, and also it flickers with the indicator, or door open, etc...

reminds me I should do this on the 400SX (done on the 350i ages ago).

Note: The V8 may be wired this way, but my 2.8 doesn't seem to be....It does have an earth which goes through a bolt on the ignition coil, which feeds the wiper motor, but the guages appear to be fed by a wire from main loom (i.e. down the wing).... But I don't know if that's original or not, it seems like the same type of wire, but hard to tell for sure. But then mine is one of the 'all black' ones, so probably stuff changed later (like everything else !)

It is always a good idea to add some new earth wires - I fully agree with that !

Edited by RCK974X on Wednesday 5th March 19:31

[GOG440]

adam quantrill said:

The earthing for the dash goes through the bonnet pull cable. This is highly unreliable and being steel tends to corrode.

So run an earth strap from the rear of the engine where the battery strap is, through the bulkhead grommet, to the bonnet pull end in the cockpit - you'll see a metal bracket up to the dash.

That should help with stuff like when you put the fans on, the battery voltage droops, and also it flickers with the indicator, or door open, etc...

reminds me I should do this on the 400SX (done on the 350i ages ago).

Thanks Adam this is a really useful bit of info, having had a chat with my mate who used to be an auto electrician (he works with BIG wires these days for national grid)he said that the issues with the gauges were most likely to be an earth issue.

[GOG440]

I spent an hour or so poking around yesterday, managed to find out what one of the issues is, at some point someone has had the drivers door off,when they re mounted it they ran all the wires so that every time you open the door the hinge crushes the wires, there are a few in there that are showing signs of wear and one that is completely severed.
How difficult is it to take the door off?
I have half a mind to just get the aeromotive guys to sort these niggles.

[wooly350i]

Gog,from what I've read you need to remove bolts at catch end of door to remove it and wires too to give access to door structure and hinges, its something I've nor tried yet but intend to,keep us posted.