Side lights not working

[johnwill]

The Wing lights and tail lights have stopped working on my 4A. Headlights, Indicators and brake lights still work fine. All the bulbs seem to be OK, but I found a blown fuse, the lower of the 2 in the fuse box.

I put a new 25a fuse in, and all the bulbs had a glimmer to them, but I then noticed the fuse itself was getting hot, so switched off, and removed it.

As I haven't needed to use my lights for ages until recently, this could have gone un-noticed for awhile. Car has run fine otherwise.

The only electrical changes I've done recently was:

Alternator packed up a few weeks ago, so changed that.

Put a new horn push in, involving threading a new wire down the steering column. I undid the "holding" bracket underneath the column to do this. I've checked all the wires I may have disturbed are still connected.

Any ideas on what to check please?

John

 

[RobH]

Sounds like a partial short to earth somewhere in the light circuit John. Perhaps in your work under the dash something has slipped and is touching the metalwork?

According to the wiring diagram that fuse powers the front and rear sidelights and the number plate lamp, and the panel lights so it could be on any of those three circuits. There should be  three red wires connected to one end of the fuse. As a first step try disconnecting each one of those in turn until the fault clears - so you know which circuit is at fault.

(Since you say the lights are on very dim my guess is the fault is on the panel lights. That circuit is fed via a rheostat which might be limiting the fault current so the fuse doesn't blow straight away but just gets hot.)

 

Rob

Edited July 2, 2019 by RobH

[johnwill]

14 minutes ago, RobH said:

Sounds like a partial short to earth somewhere in the light circuit John. Perhaps in your work under the dash something has slipped and is touching the metalwork?

According to the wiring diagram that fuse powers the front and rear sidelights and the number plate lamp, and the panel lights so it could be on any of those three circuits. There should be  three red wires connected to one end of the fuse. As a first step try disconnecting each one of those in turn until the fault clears - so you know which circuit is at fault.

(Since you say the lights are on very dim my guess is the fault is on the panel lights. That circuit is fed via a rheostat which might be limiting the fault current so the fuse doesn't blow straight away but just gets hot.)

 

Rob

Rob.

Forgot to mention the panel lights are out too...  No Rheostat, i took it out ages ago and just connected the corresponding wires.

I'll check the earths under the instruments and the wiring around the column too, but follow the 3 red wires advice as my next step.

Thanks

 

[johnwill]

As a follow up to this, I finally got some time last night to investigate the "short" issue. So, removing the red wires in turn showed it to be the panel lights were the problem as you suspected Rob, so spent some time checking all the connections and wiring. I focussed on the area around the steering column, as that was the last thing i worked on. When I fitted the new horn push wire, I took off the "under" cover for the wiring on the column to make getting a new wire down the column possible, including undoing the steering column bracket right behind the dash, so I decided to retrace my steps to see what I could find.

In doing this, I noticed I had trapped an instrument wire between the 2 "halves" of the column bracket. Once freed, I could see it had bared the wire, so insulated it, and problem solved.

 

Thanks for your advice Rob, helped a lot.

[RobH]

Glad you fixed it that easily John.