Blowing fuse?

[bosco659]

Not for a bike, but on my brother in law’s ATV. He has a Honda Foreman 4X4 and it was running great the last time he used it, then he went to start it and everything was dead. He checked the 30A main fuse and it was blown. He replaced the fuse, it started right up and he used it for a while (total time unknown), then went and parked it, turned off the ignition, heard a pop and the fuse blew again (after it was turned off). I told him to search for bare wires that a mouse may have created but what’s puzzling to me is why did the fuse blow after the ignition was turned off (and didn’t blow while running)?

Any thoughts or theories? If he can’t find anything he will be dropping it off at my place for inspection.

 

[Jan_P]

First thought is shorting to ground in ignition lock -- water in it ?
One fuse only ?
is it called Hot wiring in English by pass it for testing
But please do the read up so there is no other elctronics than can get damged

 

[bosco659]

One fuse only. The fuse will blow immediately when the ignition is turned off.

 

[Jan_P]

One fuse only. The fuse will blow immediately when the ignition is turned off.

So for getting more info .The fuse is blown . ignition off .It is then possible to put in new fuse
Not blowing
Start up .And then when the ignition is switched off the fuse blows again.

I am then thinking a heat dependent problem still in the region of the Main Switch
Not seen the wiring but usually power goes straight there .Except for the starter maybe.

If you can find an online wiring we can have a quick look

 

[bosco659]

So for getting more info .The fuse is blown . ignition off .It is then possible to put in new fuse
Not blowing
Start up .And then when the ignition is switched off the fuse blows again.

I am then thinking a heat dependent problem still in the region of the Main Switch
Not seen the wiring but usually power goes straight there .Except for the starter maybe.

If you can find an online wiring we can have a quick look

Report back from my brother in law. Put in another fuse. Sparked when installing but didn’t blow. He did this with the ignition switch on and off. So far, to my knowledge, the fuse hasn’t popped. I’ll look for a wiring diagram tonight. Thx

 

[Jan_P]

Yes that is where I am at
When the circuit is in use be it a HiFi or other device the current passing trough heats up the
circuit board or connectors wiring and all ..closing an air gap.
In position Off cold fine
In position On in use fine
Bu in that operating stage heated the gap in position Off is no longer there .
Moving the switch POFF
And then it cools down And Off the gap comes back Fine

I believe it is in the Switch

 

[bosco659]

My brother in law dropped off his ATV and I had a quick look at it. The main 30A fuse will blow immediately upon installation. The ignition switch was suspect so I dismantled the machine to get at the wiring harness (Big pita). I disconnected the ignition switch and the fuse still blows. Right now I don’t have a wiring diagram. I was thinking I’ll have a go at it again tomorrow. I think I’ll hook a light bulb up to the fuse holder and start disconnecting wiring harness connectors until I can get the bulb to turn off. Then I can trace that circuit back to find the problem. Any thoughts on doing it differently?

 

[gggGary]

Sounds like a good plan, can you find and unplug the voltage regulator? I might start there.

 

[bosco659]

Sounds like a good plan, can you find and unplug the voltage regulator? I might start there.

Will do that Gary. Thx. Very unfamiliar with everything about this machine so troubleshooting will be difficult for me - will do some late, on line searching for location. Could the fuse blow with a bad regulator even with the ignition off?

 

[Jan_P]

Do you have a full name on the machine --- Type And year model or so to see what is before the switch
On an XS 650 the first circuit to disconnect for testing would be the charging .as mentioned regulator and alternator connectors.

Since the fuse blows everything off --- a Voltmeter measuring resistance to ground can also be used
One the black probe at ground and with the other connect at points upstream . Fuse and battery out.

 

[bosco659]

Do you have a full name on the machine --- Type And year model or so to see what is before the switch
On an XS 650 the first circuit to disconnect for testing would be the charging .as mentioned regulator and alternator connectors.

Since the fuse blows everything off --- a Voltmeter measuring resistance to ground can also be used
One the black probe at ground and with the other connect at points upstream . Fuse and battery out.

I believe it’s a 2003 Honda TRX450FE

 

[gggGary]

 

[Jan_P]

A wiring schematic would help
I could not find one
But there is a connector going in to pos # 5 regulator in gggGarys picture above One could try to disconnect it and se if the fuse or control bulb is affected
and also try disconnect # 6 rectifier

Be careful so there are no sparks and so fex 2 fries

 

[gggGary]

not 100% this the right diagram and it's a bit fuzzy.

 

[Jan_P]

I saw something like that also but that one here has multiple fuses a box 3 o clock to the right
If I remember correctly the one I saw had a 30 -A And a box
Mr bosco please check if there are more fuses
Ill be out painting an so for a While

 

[bosco659]

not 100% this the right diagram and it's a bit fuzzy.
View attachment 249739

@gggGary, here’s a clearer pic of what I believe is the diagram for this machine. I pulled the plug for the VRR and the fuse didn’t pop. I tested the 5 pins (green, red & 3 X yellow) and the one yellow and red wire were going to ground (against the metal body of the VRR). i trust this tells me the VRR is done. I also get continuity between that same yellow pin and the red one. Thoughts? Thx!

 

[bosco659]

The rest of the diagram

 

[gggGary]

Will look n think over get back to you.
But do the diode test. Each yellow against red and ground reverse leads repeat

 

[bosco659]

Will look n think over get back to you.
But do the diode test. Each yellow against red and ground reverse leads repeat

Yes will do. Just saw that on a YouTube vid. Thx

 

[bosco659]

Does the VRR body need to be grounded, other than for heat dissipation?