My son has his first bike Suzuki Marauder 125 2004. Long story short no problems apart from flat battery due to lights left on. Battery on charge so decided to refit passenger saddle and panniers which didn't come with bike. Had to drill out the back holes as the snapped bolts were still in them!! All done no problem bike washed and parts polished ready for outing. At the same time set the chain adjustment as the chain was a little loose.

Replaced battery now charged. Bike started no problems and he took it to see a friend to see if adjusting chain had sorted sluggish take up. He called said all ok and wouldn't be long. This is where it all went wrong!!

On setting off to return he said bike started and he went to ride away when it just cut out and a lot of smoke started coming off under the saddle through top of engine and up to the starter button. He turned off the ignition as quick as possible got off and blew away the smoking area seeing immediately that it was caused by melted wiring cover. On removing the saddle it was evident the problem was wiring overheating. The lights still worked front and back as did brake light and horn but there is no ignition light on turn of key and at that time the indicators did not work.

On visual investigation we found:

Wiring under the saddle from the part of yhe loom to the flasher relay has melted outer showing exposed cores and loom cover melted.

Tracing loom through to connector above engine again where wires exit loom to connector showing melted cover exposed core but only one of the four going in to the connector. Unable to trace further as wires enclosed in loom cover or taped. Using simple 12v tester not a meter as don't have one.

Turned on ignition and tried to find any live feed.

No ignition light on dash. Nothing at starter button. Burnt wire at connector is not live either on or off. Three exposed wires under saddle at indicator relay appear to have voltage with ignition on and to my surprise the indicators were operative. In fact all function to the left switches lights indicator and horn work when ignition on.

Found ignition circuit from battery to solenoid 12v shows ignition off. From solenoid 12v shows ignition on. Cant get to coil as under petrol tank. Found starter lead but couldnt get tester to light either ignition on or off. The wires at the connector are melted or beyond. Obviously futher investigation is necessary but without a meter what can I do? What could have caused the wires to have melted?

Assume power surge or constant power where shouldnt as would have to be sudden for bike to just cut out . Are there any helpful persons more knowledgeable out there give an old parent some advice before he has to hand over his wallet to auto electrician! I can source most of the parts and a second hand loom if this one can't be repaired or cheaper/easier to complete replacement.

I am going to try and strip the casing from the loom in and around the affected areas today to see what the extent of the damage to wiring is.

  • Hi Andy, I have tried to edit this into a readable form, but am still uncertain as to exactly what you are asking. Is it how to diagnose, or how to fix?
    – Rory Alsop
    Commented Sep 1, 2016 at 12:01
  • Its actually a bit of both....enlightenment.
    – Andy Green
    Commented Sep 1, 2016 at 12:18
  • On the 125 I used to own, the petrol tank was held on by one bolt at the rear (you had to remove the seat to get at it). Just remove that one bolt, disconnect the fuel line and the tank could be pulled up from the rear and removed. Hopefully it's as easy on your bike as well.
    – TMN
    Commented Sep 1, 2016 at 12:45
  • Is there any additional information you can provide regarding data from your investigation? You can edit the question and add in the additional information. Commented Sep 1, 2016 at 23:35
  • I think you have a lot of words. I"d like to see the edited down piece. Technical only, symptoms, etc. Who what were just adds to the confusion. Commented Sep 2, 2016 at 5:58

1 Answer 1


This is more like a murder mystery

I believe a few things have happened

  • wires have been routed

  • Connectors have been connected

Bike gets ridden, it smokes the wiring loom.

At this point, there is smoke coming from under the seat. The seat had been removed and replaced. Is it possible a wire became pinched in the process?

Routed over the top of the frame where a seat might expect to be mounted on perhaps.

Frequently, when looking for issues it's best hit the rewind button regarding all the last changes to the device you are attempting to diagnose.

I suspect a wire was routed incorrectly and pinched under the seat due to poor routing which resulted in your configuration.

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