GPZ500S ignition circuit fuse

[dn38416]

As may be evident from my other posts i am not a particularly capable mechanic, this is especially true in respect of electrical systems. Would appreciate any basic pointers on this:

Was giving the bike a run around as i've been doing every 2-3 days for food etc. Was on a longish start-stop journey today, came to a set of lights and the electrics completely went, no neutral light and no noises to suggest the battery was just low. (Cutoff switch wasn't on, and side stand wasn't down!). Main fuse was OK, but the 10A ignition one was blown. Switched it over with the spare - which blew straight away. There's some other old threads on the ex-500 site, but i can't quite follow some of the suggested approaches.

Am i right in thinking that i need to
1 - trace through the entire ignition circuit for signs of fraying?
2 - Then test sections with a multi-meter?
3 - rectify wherever it's shorting. Presumably replacing a wire section.

I am looking at this wiring diagram and the ignition circuit looks pretty extensive. Plus if i recall it's all wrapped together in the main harness - is there a structured/systematic approach you would normally take to checking this?

Like i say any basics would be really appreciated. Beyond charging the battery i haven't touched the electrics on any vehicle before.

Cheers

[Easy-X]

This 10A fuse, any idea what it is? Squinting at the diagram (aaarrrghhh! sideways) I'd guess it's the fuse for the earth connection
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[dn38416]

[stinkwheel]

1st or 2nd gen GPZ500? (pre or post '94).

The A, B and C models had a self-destruct alternator rotor as standard which almost inevitably bombs into a cloud of magnetic shards at some point. Chaos ensues. If this happens and you manage to fix the wiring and clean all the magnetic metal filings out of the engine, electrex make a non-grenading replacement rotor.

Hopefully it's something less spectacular like a wire trapped under bodywork but if it's a 1st gen blowing an ignition fuse, I'd check the rotor before further attempts at starting.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[dn38416]

Luckily it's a second gen (E10 twin disc version).

I don't have access to my usual work area because of the virus, so any work will have to be roadside. Not looking forward to pulling the wiring apart!

[stinkwheel]

As a fault finding aid. If you plug a bulb and bulb holder in where the fuse that keeps blowing is, the bulb will light brightly instead of the fuse blowing.

Fuses usually blow due to a short circuit so if you correct the short, the bulb should go out/dim. Can save a fortune in fuses and prevent further damage to the wires.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[dn38416]

Cheers, that makes sense - is there something purpose built for that or do you mean like one of the bulbs used on the instrument cluster?

(Sorry, i am googling but probably the wrong terms)

[stinkwheel]

[dn38416]

I got one of those standard probe/screwdriver testers for cheap. Went to test it today - although only one fuse is blown (visible inspection), there wasn't any current going through any of the others except for the accessories and fan one. Tested the main one and that was fine.

I took the fuses out as well and stuck the probe in the connectors, but again in the dead ones there was nothing - you reckon that could mean something up with the junction box?

Come the weekend i'll take it apart and have a go moving the wiring around, but it's a bit sus that the others are out too.

[stinkwheel]

I'd check the ignition switch early doors. it makes and breaks multiple connections and they don't all always happen. They can fail so it gives you accessories but no ignition (all the dash lights come on but it won't start).

Also check both ends of the main (unswitched) feed from the main 30A fuse to the ignition switch for corrosion running back up the insulation. It's the fat white one.

I've had two GPZ500s and a KLE500 and the above faults happend on all three bikes.

The junction/fuse box CAN be opened up and visually inspected. I've done it before, just a long time ago, I recall it being a bit of a fiddle and much ado with pushing plastic tags in with a short screwdriver then pushing against the bit the connector block goes into. There are microrelays in there that can stick. Sometimes they just need a flick with a fingernail.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[dn38416]

OK this might be in part because i'm a moron.

I went out and pushed and prodded some of the wires around the main fuse and the ignition switch (although nothing was obviously trapped, corroded or anything), couldn't quite see the side stand one but gave it a push anyway.

Ignition on and everything seemed OK. The other fuses (turn, tail, head, horn) were all working fine - presumably because i needed to actually have the ignition switch on and working before they would work.

One thing that's still bugging me, and stopping me actually going on it, is that the first time i just switched over the fuse (with the spare onboard) it blew the replacement straight away when i turned the ignition on - which suggests there's actually a short or something, which i haven't found. Or do you sometimes just get fuses that just blow?

[Nobby the Bastard]

[dn38416]

the ignition fuse is the one that blew, so i replaced it with the spare, which then also blew.

[dn38416]

They were both the right 10A ones btw. After blowing the spare i bought some new ones as well, which is what's in it now.

[Nobby the Bastard]

[Groovin]

Got a copy of an old Haynes here if you want it.
87 to 99
You are welcome to it if you need something to help with learning.

[dn38416]

No the second replacement hasn't blown. I rode it yesterday for a few miles and it didn't go. My issue is that the first replacment i put in blew straight away, which suggests to me that there's an underlying cause / short which made it do that and which i haven't really fixed. I can't see why a fuse would just go without there being a problem elsewhere within the circuit, but i'm sure it happens?

Cheers for the offer, i have a haynes manual at another location and the pdf with me. Funnily enough I think the wiring diagram is the first instance i've seen where the E10 model is different to the other E models.

[stinkwheel]

Fuses can blow straight away for no reason then the next one is fine.

However it is more often due to an intermittant short. These are usually where a wire has chaffed through rubbing on bodywork (where the loom passes the headstock is classic) or has been trapped/squashed between two componants (under the tank, seat, side-panel or engine cover).
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Nobby the Bastard]