Rear left side light fuse blowing golf mk1

So after taking the golf (mk1 gti cabriiolet 1988) out noticed that the rear left side light was off but right side was on.
I then checked all the other lights just to be sure and everything works (indicator, brake revers light) just the rear light when headlights are on.

After swapping bulps and nothing helping i then checked the fuses and fuse n°7 (left tailight) is blown so I put another in and after turning on headlights blown straight away.

Could this be an earth problem even though all the other lights are working or mainly a short somewhere between the fuse box and the bulb?

Any help would be appreciated

Jon

 

  A blown fuse indicated that somewhere between the Fuse and the rear taillight unit there is a short.  I would say that if you take out the bulb and then replace the fuse.  Turn the headlights on and if the fuse blows then it is between the socket and the rear bulb socket.  You could also check for the short by measuring the one side of the fuse to the frame, and if there is 0 ohms you know that the white wire is the issue. The wire could be nicked and shorting to the frame.

The fuse would only blow with a significant overcurrent - most likely a short to earth somewhere in the tail light circuit. A poor earth would just reduce the current flow through the bulb. But isn't S7 supposed to protect both tail lights?

Ok so I've taken out the bulp and put a new fuse in but still blows after turning on headlights.
Would that mean that the wire between the fuse box and bulp socket is nicked and shorting to the car or is it something to do with the actual light socket ?

I'm almost tempted to cut the wire from fuse box and just run a new loose wire from it to the liight socket and see if it blows.

Let me know your recommendations










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typ_53b said

But isn't S7 supposed to protect both tail lights?

I misread the wiring diagram. Fuse S7 feeds the front left side light and the left tail light, so the short to earth would be either in the circuit  for the front left side light or the circuit for the rear left side light.

As a next step, I would visually check the wiring loom leading to the front left side light, and check the front left side light bulb and holder. Then follow up Briano1234's earlier suggestion below. As an alternative you could check resistance between the feed wire and earth at each lamp instead. From the wiring diagram it looks like the feed wires to the front and rear left side lights are grey/black, and earth is obviously brown. If you get close to zero ohms between feed and earth (as opposed to 10 ohms or more), you have a short in either the front or rear side light circuit.

Briano1234 said

You could also check for the short by measuring the one side of the fuse to the frame, and if there is 0 ohms you know that the white wire is the issue. The wire could be nicked and shorting to the frame.

 

Ok so I've narrowed it down to the left front running/side light.
I didn't notice it wasn't on which is why I was so focused on the rear left tail-light.

Anyway, after inspecting the wire couldn't see anything obvious but might have to dig deeper. Either way the fuse only blows when the connector is connected to the bulb.
I did swap the left bulb holder and bulb with the right side which is running ok but the fuse still blew.

Will be buying a multimeter as the one I had was lent to me.
Would this mean that the black/white feed wire is nicked somewhere between fuse box and connector.
 

Jon Hodgon said

Ok so I've narrowed it down to the left front running/side light.
I didn't notice it wasn't on which is why I was so focused on the rear left tail-light.

Anyway, after inspecting the wire couldn't see anything obvious but might have to dig deeper. Either way the fuse only blows when the connector is connected to the bulb.
I did swap the left bulb holder and bulb with the right side which is running ok but the fuse still blew.

Will be buying a multimeter as the one I had was lent to me.
Would this mean that the black/white feed wire is nicked somewhere between fuse box and connector.
 

Most likely Ohm it out remove your boubt, as you swapped the light from side to side and the fuse on the other side didn't blow, I would suspect that you have a good handle on the issue.  Don't discount the Plugs