Mk3 Cavalier Owners Club | Vauxhall Cavalier Dot Com

Hi. If ther was power goin through an earth cable or a few cables why would that be happening. Thanks.

If you have power (current) going through an earth point it means something is switched on and using power - the return circuit is through the earth point back to the battery, this completes the circuit.

Alan

Would be possible if i had a faulty ignition switch, when the car is switched on the tester is showing a slight bit of power coming from the black and red wire, but doesn't do this on my other cav. The car isn't starting either.

The black / red wire should only be live on cranking.
It is the "50" contact to the starter solenoid.

If you are getting a new ignition switch, this may rule out any potential problems with the current one.

If you look at my WIP, Ihave recently looked at ignition switches, with all contacts and there functions being described.
(Page 64 btw).
viewtopic.php?f=21&t=4069&start=1575

vaux16v wrote:Hi. If ther was power goin through an earth cable or a few cables why would that be happening. Thanks.

In a strange way - power has to go through an earth wire to complete a circuit.

What can happen though, is that one earth may be faulty, so the circuit seeks out another way back to earth.
What we call "The path of least resistance".
By chosing a different route back to earth, this can cause other circuits to be affected - reducing voltage to another device or dimly illuminating an unrelated bulb.

We have all seen tail light clusters where the tail lights and indicators suddenly flash together when the driver presses the brake pedal etc...
Very common on Mk1 and Mk2 Fiat Punto's and many other early cars.
This was always due to corroded, damaged or dirty earth pins in the rear light cluster.

Getting back to ignition switches.
These are very basic items, but can suffer wear, contamination or other internal failure.

So yes - try a new ignition switch..
I got my last one recently for about £7 delivered.

In extreme switch failures, the switch can start to puff out smoke... so better safe than sorry.

I have a switch ordered on Thursday evening so hopefully be here tomorrow.

The 5 earth points beside the battery. Ther is 3 showing some sign of current goin through them and ther other 2 ther is nothing. Thats when the dash ignition is switched on. Im using a continuity tester and the bulb is very dim on the 3 with the current in them.

Robsey i would need you here for a few days.

If you are testing brown wires near to the inner wing they should all be either zero or very minimal voltage.
So it all sounds fine to me.

You have to remember that the earth return will only be carrying a voltage if a switch is on further up the loom.

So one brown might show voltage when the lights are on and another when the radiator fan is on.

As for needing me.
It isn't really rocket science.
Just work slowly, carefully and methodicly.

The low voltage will be due to what voltage the items in the car consume compared to how much is kicked out by the battery.

Typically a car battery kicks out about 12.5 to 13.2 volts with the engine off.
When the engine is running, the battery will show between 13.5 and 14.9 volts.
(16 volts or more and you have a problem).

Most items (called the load) in the car run at between 12 and 12.7 volts so what ever the difference between the battery output and the load is what will be left in the brown wire near the inner wing.

As an example -
13.2 volts in battery minus 12.2 volt drop from the load would leave 1 volt in the brown wire.

12.5 volts from battery minus 12.7 volt drop from load would give no voltage in the brown wire, and the load would run at a reduced voltage..(slower motor or a dimmer bulb) - you cannot take more voltage than is available.

I hope that makes sense.
Very simple circuit theory...
In practice it is more complicated than that due to losses caused by wire lengths, cross sectional area, cleanliness of connections, corrosion, wire chemical composition and so on.

Hi. Just getting back at the car today and have found the problem of the wiring.

Dont know if i wana say what the problem is because it is the simplest thing ever.

Don't worry...
The only person who didn't get a simple thing wrong, was the one who did nothing.

I have done loads of daft things in the past.
It is how we learn from our mistakes.
No matter how obvious or basic the mistake.

So go on - spill the beans.

I was thinking about what was said about it always making a complete circuit.

I was getting 8.7 volts through the earth cables at the earthing point beside the battery and then i realised that i was missing the cable that connects the battery to the bunch of earthing cables.

It done away with al the dimming of lights and the problems i was having before hand.

It was probably earthing through the engine and engine loom.

Good to know it is sorted now

Aye kind of sorted.

The check lights on the dash has stopped working, the car still starts but wont bring the check lights on when the ignition switched on.
I heard something click and thats when they stopped

Is ther a fuse that could off blown.

Possibly fuse 22 or 8 -

Fuse feeds to the Check Control unit are: -
Connector X20 of Check control.
Fuse 22 to CC unit pin 12 - black ignition live feed
Fuse 8 to CC unit pin 13 - Red battery live feed
Fuse 7 to CC unit pin 14 - Black brake light fuse
Ground wire to CC unit pin 1 - Brown ground wire

Connector X21 of check control.
Fuse 1 to CC unit pin 11 - grey black wire for left tail and side lights
Fuse 5 to CC unit pin 6 - Yellow wire for left dipped beam
Fuse 21 to CC unit pin 13 - grey red wire for right tail and side lights.
Fuse 25 to CC unit pin 7 - yellow wire for right dipped beam.
Ground wire to CC unit pin 5 - brown ground wire

So if it is a fuse, I would suspect fuse 22,
as Fuse 8 would affect many other circuits such as clock, radio and interior lighting.

Aye fuse 22 was the problem.

There only 3 of the check lights coming on now when the ignition is switched on. The ones that are coming on is the brake pads, the big bulb and the light for the water coolant tank.

Daft question is -
Do you have brake pad sensors and coolant level switch?

Big bulb hints at a side or tail light failure..
Assuming all wiring is now correct and intact.

Brake pad sensors is a pair of red / yellow wires that loop back to each other via the pad sensors.
If you do not have pads fitted, you can simply short these together.

The level switch may be a short to earth or a faulty float switch.

Again - all depends if you are confident the wiring is now correct and okay.

If all else fails, you can remove the offending bulb, and it will never bother you again.

When i switch the ignition on does all the check lights come on then go off.

Before i had the fuse blown i had all the lights coming on then goin off, now ther is only three coming on and goin off (the ones i mentioned earlier)

Yes - they should all come on for a few seconds and then go off.

So ther must be something wrong then that only three coming on.

Im going to replace all the fuses.

I have checked the bulbs and changed the check module box as i had another one.

Have you checked that all connectors are clean and securely fitted.

And the wires look okay.?

I doubt it is a sudden failure of multiple dash bulbs.

So wiring, connectors, or fuses.

Aye checked the connector's and wires. Replacing all the fuses hopefully tomorrow evening when they arrive.