Hot fuse box

[Guest]

OK, thus far you know it is the 10 amp lighting circuit. So....... I would open the headlight shell and remove the bulb. Then turn on the ignition and see if the fuse box gets hot. If it does, you know the problem is in the tail light
or rear number plate lamp. The instrument lights and indicator lamps are very small and draw almost nothing. If the fuse box doesn't get hot, the fault is in the head light. To double check that, you could remove the tail light bulbs, reinstall the headlight bulb, turn ignition on and check fuse box again

Here's what I did so far.

1) Pulled headlight bulb(visual inspection of all wires in bulb housing looks ok with no visible corrosion or bare wire) and turned on ignition. Fuse does not get hot.

2) Re-installed headlight bulb and pulled tail light bulb. Turned ignition on. Fuse gets hot.

3) Re-stalled tail light bulb and pulled headlight bulb, sprayed electronic contact cleaner into bulb housing and coated brand new bulb's contacts with di-electric grease and fuse still gets hot.

Suggestions on what to do next.

 

[Rijko]

Cool, that's a good indication the issue may be in the headlamp wiring.
I would start following the wire powering the headlamp, it goes through several connectors.
Those may be dirty or corroded, leading to excessive amperage through the wiring.

Clean connectors.
If that does not solve the issue, measure how much voltage is on the headlight,
that may tell you something.
If that still does not give you a solution you'll have to break out the ohm meter and see
where the power flow goes bad.

 

[Guest]

now that triggers a memory.
My buddy has a very nice GS1000 with a Dyna 2000.
He had been to 3 shops before i first met him because the bike would sometimes run right,
sometimes run on 3&4, but also sometimes run on 1&3, which led most guys looking at the bike to believe that had to be carbs.

I checked his carbs and they were like new, floats at the right height etc.
Fortunately i had a Dyna S lying around for a project i had not started yet.
Eyeballed the timing and we could tell directly the issue was found.
Sent the ignition off to Dynatek who checked it and found it to be bad.
They made him a nice offer on a replacement unit which he happily accepted.
The bike has had no problems since.

Do you still have the original ignition, or have access to one just to check if that's the issue ?

Maybe the Dyna 2000 is spliced into the headlamp wiring causing several symptoms/problems at the same time.
Disconnecting the Dyna 2000 might solve the heat issue on the fusebox, at least it's a quick and simple thing to check.

edit : Earl's suggestion would be my first try btw.[/QUOTE

Have already checked that by disconnecting stock power/ground to Dyna 2000 and running separated hot and ground to it. Still gets hot.

 

[Grimly]

I'd be looking for a partial short somewhere on the headlamp loom, either in the shell, or at the bar controls, or the loom wrapped around the headstock.
The last part is a favourite failure mode on old GSs.
Once you find the short, repair it and wrap your loom with SpiRap.

 

[earlfor]

OK, this is kind of nutty, but I'll throw it out here. We're looking for a big amp consumer (my guess). The horns are an oddity. Unlike everything else, horns are hardwired hot and switched negative. If there is any electrical bleed through in the horn bodies, there will be draw without the horn button being active. Horns are used intermittently, so could be piggy baked onto most any circuit. The headlight circuit is a negative ground circuit. The horn circuit (in a manner of speaking) is a positive ground circuit. It would be easy to check for fault. All that is needed is to remove the + plug from each horn body. Could it be this simple? Just head scratching. heh

 

[Gorminrider]

Just verified that the main fuse is still getting extremely hot after about a minute with the key on. As suggested I started pulling fuses. The first one I pulled was the 10A HD. LAMPS. The main fuse no longer gets hot. So it seems that we have narrowed the cause, now for the solution

Logically, not necessarily. You've merely lessened the main fuse's load by subtracting the headlight's 55-65watts..

If the problem is NOT a connection near the fuse, and the 30amp main is NOT blowing immediately , the problem IS that something has been added or is malfuntioning such that the system is drawing VERY NEAR 30 amps. That is more than the wiring is designed for. However, since the sub-circuit fuses (IGN,Lighting,Turn etc) are not blowing, the "Extra" is below their amp rating.... ie: brakelight which normally has no load...you could tap another 5 amps? there and it likely wouldn't be bothered but as a sum, increase the load to main....

It might also be tthat the "greedy circuit" has been directly wired to the main going to key (Red)and back to the fusebox Orange). It may even be the R/R which has no fuse between it and that RED wire. (is it warm when bike not running?) It might be the greedy one is tapped into another sub-circuit.... Or a failed turn-signal relay or gee-
maybe Earlfor's idea is NOT so nutty and the horn's coil is stuck....

In the same train, perhaps your headlamp bulb is drawing more than the usual 55-65 watts.