Mopar Muscle Association UK

Got an electrical glitch that is driving me nuts! Rewired the Valiant and everything works as it should except for one thing, the side maker lights flash with the indicators. I have traced all the wiring back and nowhere is the indicator circuit linked to the sidelight circuit. As you know the front and rear lights use a twin filament bulb to provide sidelight and indicator at the front and sidelight/ indicator/ brake light at the rear.
Ok, this is what's happening, with the front and rear bulbs removed, you have a flashing live on the indicator terminals, nothing on the sidelight terminal with the lights turned off as you'd expect.
Add 1 bulb either front or rear and do the same test, you now have a flashing live on BOTH terminals on all the other 3 bulb holders, which explains the flashing marker lights. This leads me to conclude the live is passing across the twin filament bulb to the sidelight circuit, but how can that be, the filaments are separate. Doing the test in reverse with the sidelights gives the same result. I have connected a bulb directly to rule out the bulb holder.
So now I'm stumped, what am I missing here?

Good one this

I take it we are using bog standard bulbs and the fact that all bulbs are faulty is doubtful


So we send 12v to the bulb now if there was no earth

(or an earth with high resistance) can check earth with a (ohm) meter between battery - and bulb earth


The 12v you sent to bulb wants to get back to negative so the only path it can take is via the 12v for the other filament. ( which should not be earthed it's a 12v feed he said) but there is a bulb connecting that 12v feed to earth further up the line !

There may well be a connection between the filaments but of such a high resistance that in normal operation it is not shown


This is very common on dirty trailer connection

Check all earths

I've tried several bulbs to rule that out. I have earths soldered to the outside of the bulb holders but I haven't checked them for high resistance. Ok, I'll assume It's an earth fault and look further into that next, Cheers!

Yep. Earth fault Blue.

I had a couple of similar issues before, one was a brass button & tail in a lampholder grounding to the inside of the holder, the other was a car that some tw@ had actually wired the side markers to the indicators.

If be thinking bad earth. As described above the current is making its way back through the second live.

the outer section of the bulb shank is shared between the 2 filaments.

and the side light circuit is acting as a more desirable earth than the bulb holders/light units/car body. i.e both flash at half brightness

electricity is lazy and is taking a route back along the wire to the side light switch (that in itself is not odd some switches when off earth the contact. you put in in 12 volt when switch to on, but the wire to the light is switched to earth when off.

take out the side light switch and see if it all works with the switch not touching body metal. if it does this confirms its an earth at the light unit problem

then put it back

next
get a long bit of wire

screw it to the bodywork with one of the self tappers used for something else

use it as earth to check a bulb works direct from battery +

if its nice and bright you have chosen a good earth

first all indciator bulbs out.....

next take that wire to each lamp in turn

pull the full lamp unit off the car but still wired in.
put in the bulb

set up your test (indicate and side lights) and clamp the other end of your earth wire....
to the lamp unit screw hole

to the lamp unit body (pot metal ...did you paint the interiors white? is the bulb holder earthing properly to the pot metal body of the lamp unit or is the earth strap across the outside back of the reflector from the holder to the metal lamp unit body there)

to the lamp unit bulb holder for sides and indicator. zinc passivated metal clip in shenanigans with squeeze togther clamp or spring clip to hold it into housing

if that fixes the problem

put the lamp back in
if problem comes back

wedge a wire under the bulb holder edge (zinc passivated shennanigans) as you clamp it into the houisng and put the other end under the screw that holds the lamp in.

passenger side lamp usually has something simlar anyway that runs from the body to the self tappers used for chrome/stainless ring that bolts down to clamp in the sealed beams or H4 lamps

do the next one

if you can't get it to work

instead of putting your long wire under a self tapper somewhere on the car
run it to the battrey negtive

if that then works you problem is body earthing/earth main strap related.

if your side lights light a bulb in the dash
make sure the dash and dashlight bulb holder is earthed.
do the blinkers in the dash work?

they too need to be properly earthed. the standard push fit black bulb holders earth through the metal dash gauge box or via the circuit board to a circuit board screw that hold the circuit board into the metal gauge box. either way the route from the dash bulbs back to car body needs to be good as well.


if all else fails

mount your side light switch in a plastic panel with no earth via its screw down spiky washer and nut collar

Dave

Thanks chaps, got back to it today and sorted it, kind of
I had 2 problems, I was testing the back lights with the bulb holders out of the lamps, no earth you mong! The LED bulbs I had in the front are faulty and feeding across, new pair of normal bulbs and no more flashing marker lights. Brake lights work fine. But now I think the electronic controller is on the fritz. As soon as you turn the ignition on, the hazard lights come on, you can manually turn them off but as soon as you select either turn signal it goes back to hazards....
Time to email the manufacturer I think.

Ahhh so you have gone completely off piste

nobody mentioned LED bulbs

dependent totally on wether the 6 year old chinese child who soldered them paid attention when she got his 2 seconds training

Dave