Problem with blinking license plate light

[subdivo]

During the restoration of the galley, we had to take off the hatch, disconnect all the wires and reconnect them. They were carefully mapped and reconnected. We took extreme care with this as we didn't know which wires belonged to what (since we didn't build it ourselves).

Anyhow, now to the problem. Testing all the lights last night, we discovered that when you turn on the left-turn signal, the light over the license plate turns off each time the left tail light comes on. So you have the light going from tail light to license plate, back and forth.

This could have very well been like this from the start, as during the daylight (which is the only other time we'd tested the lights prior to disconnecting the wiring) you can't see the light over the license plate.

Could someone give some pointers as to where to start? I was thinking the connection of the wire to the license plate light perhaps?

I also noticed that the wiring bundles are always 1 to 1, except in the case of one set which is 1 wire to 2 (is that normal?).

Thanks everyone,
Michelle

[Dale M.]

IF it were me I would start with verifying the grounds to the offensive turn signal and the license plate light.... I may be that the license plate light (which should be on tail lamp circuit) is helping to supply ground for turn signal there for flashing when turn signal is on... Does license plat light come of with just tail/marker lamps?

On the 1 to 2 bundle it may be for BOTH tail lamps or ground circuit for lamp holders... Best thing is to do first is to identify what wire in the bundles provide what lighting function and make a list so you have colors coordinated with function...

Real common circuit using flat 4 wire is ...

Brown = Tail lamps + license plate
Green= Right Turn/Stop
Yellow=Left Turn/Stop
White= Ground

Some wiring help may be found here....

http://www.etrailer.com/faq-wiring.aspx


Dale

[bobhenry]

Yep ! Poor ground.

To test the easiest way is to run a 12 foot wire from the license plate light GROUND side to the frame of the towing vehicle. If problem is resolved it's the ground.

Best fix is a dedicated hard wired ground wire from each and every light to a hardwired ground to the tow vehicle.

[subdivo]

Hi - it's Phil here - Michelle's other half.

Just to clarify (and it may very well be the ground that is the issue)

When the left signal comes on the licence plate light gets brighter then dimmer, but it doesn't turn off completely (i.e. it mimicks the signal light).

If there are no running night time lights on the truck (i.e. headlights) I don't think the turn signal is a problem. It's only when the lights are ON and the left signal is activated.

Now, with everything sealed behind the skin of the hatch what's the best way to test the ground? Can I run it directly from the light?

[bobhenry]

clip to the brass looking barrel that holds the bulb this is the part of the light fixture that is grounded !

[subdivo]

10-4! Thank You!

[dh]

I had a similar issue, my right turn/stop would controll running lights, but they would come on dimmly. I had a broken T/S filament that was touching the marker fillament in the right T/S/M bulb.