27 Year Old Wiring popping fuses....help

Hi
I have 1990 90, originally a 2.5TD now with a 200tdi engine. All has been fine, but recently started blowing both side light fuses. The main beams come on OK but no sides and it has also popped the stereo. Side light bulbs will light for a few seconds then I hear the fuses crack!
Read most of the threads, and whilst I’m happy to rip out the back end wiring and replace the lights with LED’s, but I’ve got not idea how to fault find?
I opened up the in-cab fuse box and both side light cables look thinner than the others, and one definitely is showing signs of overheating.
Do I run a whole new set of wires to the rear, (removing dash sounds very scary!!). There has been a break in the wiring to the rear, mid chassis, it’s been cut and joined using a dodgy connector. Do I replace this whole rear section, and hope that the fault is in the rear?
Where do I start, it’s my every day runner and I can’t afford the hours of an output electrician!
Thanks in advance!!
Bruce

The loom to the rear starts at a plug in the engine bay on the bulkhead above the point where it goes into the chassis. Disconnect and see if fuse still blows. If it does not then problem is in rear loom [common fault]
An often used fix is to run a length of trailer cable along the outside top of the chassis rail to the rear.

Thanks! Will try unplugging in the AM and then go down the trailer cable rout if this is it.
Cheers

MontyChops said:

Thanks! Will try unplugging in the AM and then go down the trailer cable rout if this is it.
Cheers

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Do you have a multimeter?

MontyChops said:

Thanks! Will try unplugging in the AM and then go down the trailer cable rout if this is it.
Cheers

Click to expand...

Although trailer cable is possibly slightly cheaper, if it turns out to be the rear loom I would get an proper replacement from auto sparks. think they are about £70ish but are worth every penny as far as I am concerned. It spent a long time trying to make my old loom good on both of mine and in the end replaced with the auto sparks looms. This solved all of the issues I was having, is a straight swap, and uses all of the correct connectors.
I would still run it along the top of the chassis however, with both of mine I put the loom into plastic conduit, bound it with loom tape and then fed it along the top chassis rail for ease of future maintenance.

Al2O3 said:

Do you have a multimeter?

Click to expand...

I have....any top tips on how to meter it out?
Ta

dag019 said:

Although trailer cable is possibly slightly cheaper, if it turns out to be the rear loom I would get an proper replacement from auto sparks. think they are about £70ish but are worth every penny as far as I am concerned. It spent a long time trying to make my old loom good on both of mine and in the end replaced with the auto sparks looms. This solved all of the issues I was having, is a straight swap, and uses all of the correct connectors.
I would still run it along the top of the chassis however, with both of mine I put the loom into plastic conduit, bound it with loom tape and then fed it along the top chassis rail for ease of future maintenance.

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Good advice....I’ll try to find the problem area first then see it it’s a whole rip out job or not.
Ta

MontyChops said:

I have....any top tips on how to meter it out?
Ta

Click to expand...

MontyChops said:

I have....any top tips on how to meter it out?
Ta

Click to expand...

I'm no auto spark. However, you may have a short on one of the sidelight feeds. I'd start by taking a bulb out (or disconnect the live feed from the bulb unit) and test for continuity from the live to an earth point. You shouldn't get anything unless there is a short on that positive feed. Do the same on other side.
Another thought, you do have the correct bulbs in? Simple things first.