Spare Engine connectors near alternator

[mister2mk1]

This is the same as mine -




regards

[PW@Woodsport]

Disconnect the following...

Engine bay fan
Alternator plug
Engine bay fan relay
Combination meter

Now do a continuity test between the Yellow wire on your alternator plug to earth, there should be no continuity at all between that wire and ground (batt -) with everything disconnected.

If there IS continuity then you have a fault on your wiring somewhere, the yellow must be earthing out somewhere. In that case i'd try running a fresh wire from alt to clocks, remember to cut the yellow at both ends to isolate the short, although do check the condition of the inside of your N1 connector in the boot, they get corroded due to water ingress, so the fault could lie there. In fact repeat the test with the N1 connector pulled apart, test between the body side of the plug and ground, and also test between the engine side of the plug and ground, that will isolate if the short is body side or engine loom.

If there is no continuity anywhere try repeating all of the above with one component at a time plugged back in.... so start with the fan relay and see if the continuity to ground happens.

Bottom line is something is grounding that yellow wire.

[PW@Woodsport]

Another thought today while i was working.... if you do not have full continuity between the alt main charging cable and the battery + terminal you will get your symptoms as well.... the M2 connector can be a problem sometimes so it's worth checking that.

[mister2mk1]

Disconnect the following...

Engine bay fan
Alternator plug
Engine bay fan relay
Combination meter

Now do a continuity test between the Yellow wire on your alternator plug to earth, there should be no continuity at all between that wire and ground (batt -) with everything disconnected.

No Continuity here???????

also please can you tell me what the N1 connector is in the boot??

And!! What is the M2 connector

Cheers

Steve

[MartG]

N1 connector is the big white plastic connector at the left front of the boot that connects the chassis loom to the ECU etc.

The M2 connector is the grey one below the engine bay fusebox that connects the engine loom power to the chassis loom, and also provides the earth connection.

[PW@Woodsport]

Try running the engine with the alternator plugged in but the fan control relay unplugged and report back.

[mister2mk1]

I removed the Fan control relay (in the engine compartment fuse box - relay far left standing on passenger side) ran engine lights still on

[PW@Woodsport]

Are you getting a full charge rate? 14v+ ?

What happens when you run the engine with the alternator plug off? You should not be seeing any dash lights with the plug off...

[mister2mk1]

Hi Paul

thanks for your quick response - yes getting 14.4v charge at battery and yes if I remove the alt 3 pin plug the lights go out....

cheers

[PW@Woodsport]

Right, so the only thing that is putting the lights on is the alternator as you have isolated the problem there entirely.

I know you have had one or two alts on there but i really can't see what else it could be now....

To explain how it works so you may understand what is going on.

The dash lights have 12v going to one side of the bulbs, the other side (earth side) of the bulbs is on the yellow wire going to the alt. Now when the alt is not spinning it acts as an earth for the dash bulbs, so you switch ignition on and the bulbs have 12v and an earth through the alternator.

Now when you start the engine the alternator is supposed to throw 14.5v back up that yellow wire, turning an earth into a live.... and two lives going to a bulb put it out.

So quite simply you are not seeing 14.5v coming back from the alt on that yellow wire when it is running.

Try plugging the alternator back in, start the engine, and prod the yellow wire at the alt with a multimeter, and at the N1 connector, both sides of it. You should be seeing 14.5v at all of those points of the yellow wire with the engine running, but i don't think you will be.

Report back with your findings.

[mister2mk1]

Try plugging the alternator back in, start the engine, and prod the yellow wire at the alt with a multimeter, and at the N1 connector, both sides of it. You should be seeing 14.5v at all of those points of the yellow wire with the engine running, but i don't think you will be.

Report back with your findings.

thanks for your time and patience here paul - truly is appreciated.

I will try this tomorrow after work and report back -

For info I did try 3 second hand alternators but I have since purchased a brand new one.....

Just another after thought - as part of the rebuild I obviously painted the alternator brackets and engine block -- i thought that the thread of the bracket/mounting bolts would be enough to earth (if there meant to earth at all) but you dont think this could be a alternator earthing issue???

cheers

Steve

[PW@Woodsport]

Yes absolutely, bracket earthing is vital, although i would expect it to not be charging with a poor earth... clean up the mounting points or maybe run a temporary ground wire from the alternator to chassis just to make sure.

[mister2mk1]

Try plugging the alternator back in, start the engine, and prod the yellow wire at the alt with a multimeter, and at the N1 connector, both sides of it. You should be seeing 14.5v at all of those points of the yellow wire with the engine running, but i don't think you will be.

Report back with your findings.

I havent done this bit yet - have been fighting the poor running issues that I now think are cured - I have however done this bit....

Just another after thought - as part of the rebuild I obviously painted the alternator brackets and engine block -- i thought that the thread of the bracket/mounting bolts would be enough to earth (if there meant to earth at all) but you dont think this could be a alternator earthing issue???

All surface areas are now cleaned and paint free - still lights illuminating so will try the top bit ASAP

[mister2mk1]

Sorry to drag this up again!!


I still have the lights illuminated on the dash but have progressed my investigation......

Jimi's below quote is were I am............

Just been out and checked on my car.
My apologies I was working off of the diagrams and got the orientation wrong
With the Charge fuse out and ignition on
Left side of the fuse holder should show less the 1v.
Right side should be battery voltage (call it 12V)
and no lights on the dash
Still with the fuse out and now with the engine running
Left side should show around 13.8v ( alternator output voltage)
Right side should be approx the same.

Quote:
I get 13.8v with the engine running on the right side and .36v on the left???



Going by this you either have a faulty alternator (unlikely as you have tried several) or a open circuit in the wiring between the alternator and the fuse (odds on favourite)
To prove it you can use a length of wire to link between the L terminal of the alternator (you will need to keep the plug in the alt and link from the back of it) and the Right hand side of the fuseholder. The dash lights should go out.
Also check the voltage on the L terminal of the alternator from the back of the plug with the plug in and engine running, should be around 13.8v, if it's not then could be a bad contact in the plug or the alternator is faulty.
Alternator terminals

Now - what I have found is when the Alternator plug is unplugged I have approximately 12v at all three pins - I have tapped into the 'L' wire (yellow) and soldered a length of wire to this. When I plug the alt plug back in (ignition on - charge fuse in) I only get a reading of 2.25v on the end of the soldered length of wire. ????? This has to be the issue? but what is it!!!

When the engine is running the dash lights are on - I then pull the charge fuse and the lights go out if I then touch the right hand side of the fuse holder with the length of wire the lights come back on.......

Hope this means something to you and you can help......