Wiring! Aarrgh! Help required.
Discussion
The wiring loom in my Dutton Phaeton looks as if its alive and actually regenerating itself 
, I've managed to wade throught the mire and get everything working with the exception of the headlights and the backlight for the Ameter. The head lights just refuse to work, although the side lights and main beam are fine. The Ameter is however far more worring. The body of the gauge appeares to be live and vapourises the bulb holders earth lead on contact. I'm not sure how anyone can help on line, but if there is anyonr in the Bristol/Weston-super-mare area who fancies having a look, email me, theres a drink in it for you 
Thanks in advance. Simon.
, I've managed to wade throught the mire and get everything working with the exception of the headlights and the backlight for the Ameter. The head lights just refuse to work, although the side lights and main beam are fine. The Ameter is however far more worring. The body of the gauge appeares to be live and vapourises the bulb holders earth lead on contact. I'm not sure how anyone can help on line, but if there is anyonr in the Bristol/Weston-super-mare area who fancies having a look, email me, theres a drink in it for you Thanks in advance. Simon. I am unfortunately miles away, and probably stating the obvious, but it sounds like some whare along the line the earth for the ammeter is getting live feed from some where, remember that the ammeter is in series with the live circuits and not in paralell like voltmeters.
Probably telling you to suck eggs , just trace out the earth wire to the ammeter casing, you mat get lucky.
>> Edited by dicky on Sunday 12th January 10:12
Probably telling you to suck eggs , just trace out the earth wire to the ammeter casing, you mat get lucky.
>> Edited by dicky on Sunday 12th January 10:12
the body of the ammeter guage should be earthed and the bulb supply live so when you push the bulb in it earths on the guage , do you have a multimeter ? just double check everything , shame im a busy today , would have driven up and had a look for you , got all sorts of gizmos in the van for fault finding , good luck simon 
yep sounds logical, where the bulb holder fits onto, ie the dashboard say, that will be a common eath, if you say a live feed is getting on to that then, look at all the wiring close to that and see if any are bare and live to it. It is just saying you have a short , thats all, easy once found thougfh.
The terminals for the live feed and the other one, (lets call it the return for ease), both attach to the threaded posts used for securing the gauge, thats not a very good descrption, hang on. Right on the back of the gauge there are 2 threaded studs over which you fit a n section plate which secures the gauge, i'm sure you've seen on before, well the live feed and return attach to these studs. Could the gauge be damaged internaly, causing a short inside the gauge?
wow this is getting confusing, pitty you aren't closer.The n shaped plate that secures the gauge , is there anything else that also uses that same earth, ie where the plate bolts on to.
another thought, try a trace the live wires and see if any of them are touch an earth by any chance, maybe one is caught up on something sharp
hope this is some help
the ammeter could have a fault on it, maybe try putting a multimeter on amps in place of the meter and see how much it is pulling, loads will point to an earth problem streight away.
another thought, try a trace the live wires and see if any of them are touch an earth by any chance, maybe one is caught up on something sharp
hope this is some help
the ammeter could have a fault on it, maybe try putting a multimeter on amps in place of the meter and see how much it is pulling, loads will point to an earth problem streight away.
Right, I'll give that a go and report back, would that have any bearing on the headlamp problem? The head lamps were working when the ignition was switched off but when you turned the ignition on the headlights went off and only the side lights worked. Now however, only the side lights work, full stop! 
www.greengauges.com/help/faq10.asp may be some use...
The thing about ammeters, as mentioned before, is that to measure the load on the battery they are effectively part of the main power cable, in series with it. So, there is a **LARGE** current going through it esp. when starting the car etc.
What is the gauge casing made of? If it is plastic, then the illumination will need 2 wires, +ve and -ve. If the case is metal, then the case should be earthed (and the main feeds to the battery / alternator should be isolated from the case) and the bulb would normally only need a +ve supply, the -ve being formed from the case being earthed.
Stupid question, probably, but: have you checked the fuse for the headlights????
The thing about ammeters, as mentioned before, is that to measure the load on the battery they are effectively part of the main power cable, in series with it. So, there is a **LARGE** current going through it esp. when starting the car etc.
What is the gauge casing made of? If it is plastic, then the illumination will need 2 wires, +ve and -ve. If the case is metal, then the case should be earthed (and the main feeds to the battery / alternator should be isolated from the case) and the bulb would normally only need a +ve supply, the -ve being formed from the case being earthed.
Stupid question, probably, but: have you checked the fuse for the headlights????
The two threaded studs are meant for fixture only.
There should be a separate power feed to the ammeter, the other one going to the measured load.
If youve got BOTH wires connected to these studs AND its earthed, then all youre effectively doing is shorting out the feed to earth.
The bulb power feed should come from the lighting cicuit, usually powered only when lights are on.
Hope this helps.
Oh also, even if the ammeter WAS shorted internally, so long as its not shorted to earth then all that would happen is that it wouldnt read.
>> Edited by deltaf on Sunday 12th January 12:14
There should be a separate power feed to the ammeter, the other one going to the measured load.
If youve got BOTH wires connected to these studs AND its earthed, then all youre effectively doing is shorting out the feed to earth.
The bulb power feed should come from the lighting cicuit, usually powered only when lights are on.
Hope this helps.
Oh also, even if the ammeter WAS shorted internally, so long as its not shorted to earth then all that would happen is that it wouldnt read.
>> Edited by deltaf on Sunday 12th January 12:14
Right then, firstly a big thankyou to all who have posted 
. Since I last posted I havee been up to my arm pits in wiring, I only managed to set fire to the loom once and now the jobs done! 
. The Ammeter: The problem turned out to be the casing of an old broken bulb which had managed to fall out of the holder at some point, and was causing a short inside the gauge, with this foreign body removed, end of problem! (Deltaf, 
firstly, the live feeds do go to the 2 studs and the bulb holder does indeed provide an earth. Secondly, I thought you had left us due to being poor! 
) The Headlights: For some strange reason, which still elludes me even now, I had managed to get the switch wires and the feed wires the wrong way round on the relay, 50/50 chance and I got it wrong, again! Now rectified.
. Since I last posted I havee been up to my arm pits in wiring, I only managed to set fire to the loom once and now the jobs done! . The Ammeter: The problem turned out to be the casing of an old broken bulb which had managed to fall out of the holder at some point, and was causing a short inside the gauge, with this foreign body removed, end of problem! (Deltaf, firstly, the live feeds do go to the 2 studs and the bulb holder does indeed provide an earth. Secondly, I thought you had left us due to being poor! ) The Headlights: For some strange reason, which still elludes me even now, I had managed to get the switch wires and the feed wires the wrong way round on the relay, 50/50 chance and I got it wrong, again! Now rectified. Gassing Station | General Gassing [Archive] | Top of Page | What's New | My Stuff