1989 Sunsport Rear and Side Marker Lights Not Working

[Wakesupremo]

There seems to be constant electrical issues. Now, for some strange reason, I have no rear or sidelights. They worked fine when I bought it in October but now nothing. I found a fuse labelled sidelights on the firewall fusebox under the steering column and, yes it was blown. I have replaced that but all that seems to have done is made the gauge cluster lights work!!!
Is there anyone that knows the location of the ground strap for the lights on the chassis?

 

[Wakesupremo]

I have come to the conclusion that its not a grounding issue as both brake lights and indicators work but share the same ground. I have 'buzzed out' the switch pin configuration and know that its the brown wire from the switch plug. This brown wire doesn't go to the fuse box beneath the steering column, anybody have a wiring diagram that shows where this goes please? I have the fascia all out again and it disappears into the loom. Is there a relay somewhere? This also feeds the amber cab lights and side marker lights, none of which are working. What an absolute nightmare!!

 

[Ronald1955]

I have come to the conclusion that its not a grounding issue as both brake lights and indicators work but share the same ground. I have 'buzzed out' the switch pin configuration and know that its the brown wire from the switch plug. This brown wire doesn't go to the fuse box beneath the steering column, anybody have a wiring diagram that shows where this goes please? I have the fascia all out again and it disappears into the loom. Is there a relay somewhere? This also feeds the amber cab lights and side marker lights, none of which are working. What an absolute nightmare!!

Please provide year make and model of your rig. During my 46 years as a mechanic, I would disconnect the main battery and only provide current and ground with a fused battery on the affected circuit. Then I could use a test light to trace the power side of the affected circuit. This is a easy way to find a open circuit.

 

[Wakesupremo]

Thank you for the reply. Its a 1989 Sunsport.
I think there must be a plug / socket somewhere along the loom. I have put a new cable to the rear lights and now they work but indicators don't. Fronts do but not the rears. I can't see how its possible that both rears have stopped together unless theres a bad plug and socket connection.

 

[Wakesupremo]

Wow. Ive found it. Theres a 4 pin plug tucked way up above the fuel tank with no corresponding socket. I have tested for power and. Its rear lights, brake lights and indicators. Just need to contortion myself in there to extend the wiring!