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MG MGB Technical - No rear trn signals- 76b

Just got my car out forthe first time thsi year and notice tha tfront signals work fine, but I have NO rear turn signals. Any suggestions where I can locate problem are appreciated.
Bud
Bud

Bud,
Have you checked the connectors in the boot (trunk)? These can sometimes be pulled loose when loading awkward objects.
David
David Overington

Yes-, I went into the trunk to confirm the connections that are visable were connected, but I did not meter them (yet).
Bud
Charles Yanak

Also check the common ground for the lights as this can corrode over the winter and give you a poor connection. Ray
RAY

There is no common ground for the rear light clusters, they ground through the physical fixings to the wing panel. However the reversing lights, fuel pump, tank sender and number plate lights on various years do use the common ground on one of the number-plate mounting bolts.

As well as the connectors in the boot check those by the fusebox where the rear harness joins the main harness - the green/white and green/red wires in particular. But unless you have the incorrect flasher unit the front *turn* signals shouldn't work fine if the back ones aren't working, they should just glow and not flash. Or if you have a more modern turn flasher unit they might flash but should do so at double-speed. Turn flasher units that ignore bulb failure are a safety risk.

*Hazard* flashers by comparison *will* flash at more or less the correct rate irrespective of how many bulbs are connected.
Paul Hunt 2

Fun fact: failure of the common ground at the license lights will prevent the car from running by killing the fuel pump! (as a fun side note, a shorted brake light can also blow a fuse and kill your engine - two ways to kill the engine using only the rear lights, an astonishing engineering accomplishment!)

Definitely check for voltage at the green wires in the trunk, as they're easy to get to, and try your hazard switch, before you start messing around under the dash.
Sam

Out of interest, which fuse stops the engine? The ignition and fuel pump are both unfused, the brake lights run off the green fuse which only feeds ancilliaries.

There are no green wires in the boot/trunk, although there are green/white and green/red for the turn/hazard lights. It's possible but would be quite a coincidence if both these decided to go open-circuit over winter.

The hazard switch will affect all four corners, not just the rears.
Paul Hunt 2

This thread was discussed between 06/04/2007 and 17/04/2007

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