Indicator flasher unit for JCB 3C Mk2

[MrF]

Now is a good time to mention the downloads on the site, there's a mk2 manual in there with wiring diagrams that will help a lot.
I *think* the terminals are only labelled with amperages but they correspond to the layout on the fusepanels.
If its any help, a lot of my electrical issues were just plain old corroded connections where the fuses touched the fusebox tangs. A dremel with a fine brass brush cured that quickly.
Manual :-
app.php/dl_ext/?cat=5

[jcb3cmkdeux]

Cheers Phil, I'll take a look. Reluctant to jump into removing dash because I like the nice simple indicator/light stick and don't want to damage it trying to remove dash.

[MrF]

The indicator stalk stays with the dash I think as its screwed to the underside of it but yes there's a lot of things to disconnect first and its a faff if you can get away without having to.
Looking at the manual, the front worklights and rear ones are on the same fuse, as is the interior light. If all 3 of them systems are dead, probably the fuse is the first port of call, but if not, the holder then the switchgear itself would be my guess, with also the possibility of a broken wire. I like to trace through with a length of wire hanging off one lead of my multimeter on a fixed point and probe each point going back (and occasionally I probe through the wire insulation..). You can get the switchgear downwards if its secured by a front locknut, or defeat the locks if its locked by springing tabs and bring it up to get access to the terminals without having to remove the dash usually. Apologies if you do all this already, you sound fairly switched on with wiring issues.

102 & 103 are the front & rear worklights, and 40 is the interior light. the wiring carrying power to the worklights if its factory is red in the mk2 maintenance manual, but in this 3c3 one its marked as being blue/black. Its only colours, but the electrons dont care! Sadly those little numbers marked appear to be the fuse amperage ratings when you zoom in, not a marking to identify it. The worklight fuse originally is 25amp though.

worklight_wiring.jpg

[jcb3cmkdeux]

I'm an absolute novice at auto electronics Phil so all advice gratefully received thanks. I'm lucky that my machine has been stored undercover mostly.
As you suggested I got a brass wire brush and starting with the left hand fuse box, cleaned the terminals and replaced all the fuses. Pic after cleaning and pic of right hand box still to be cleaned below.


And the result of this cleaning was this....




So I'm very pleased with that progress. Rear and side light circuit working fine hopefully just need new headlight bulbs. Front work lights perfect having not worked for 30 years or so (also corresponding glowing dash switch). I'm missing a fuse cause one of the holders is bust. I need to create a bodge there. I believe that's for the rear work light circuit. The socket of the right rear bulb is damaged from when I removed a rusted bulb hence it's dimmer than the left hand side so I can fit a new socket as I've had to do for the left rear indicator.

[dixie-normous]

Looks like the rear lens arrived ok Mike

[jcb3cmkdeux]

Sure did John thanks and in perfect condition. Got it on there asap!!

[dixie-normous]

Nice to see it on such a lovely old machine, looks alot better than it did chucked inside my rusty old cab!

[MrF]

I'm missing a fuse cause one of the holders is bust. I need to create a bodge there. I believe that's for the rear work light circuit. The socket of the right rear bulb is damaged from when I removed a rusted bulb hence it's dimmer than the left hand side so I can fit a new socket as I've had to do for the left rear indicator.

Cool, a lot of my electrical problems went away with cleaning of those fuses and replacing broken switches, but then lacking cab glass means the water just got back in after so I have to do it all again once I've fixed my cab up. There's supposed to be rigid plastic covers that have a small thumbscrew fastener holding them in place that screws into that central brass fastener. If I ever get my cab bashed into shape I might draw some replacements up and 3d print some in black resin to keep the crap out, as quite often they seem to be missing/broken. But then there's a lot of things in the job queue before niceties like that might happen, I need several lifetimes to process whats in there already I think

Just a note the wiring diagram above shows the front/rear worklights and interior cab lamp on the same fuse in the fusebox. So either that doesn't correspond to your wiring loom properly being for a later machine possibly, or possibly its not for the rear worklights.
I'd probably have held a bit of wire between where the missing tang connected and the end of the fuse to test what starts working...
if it doesn't, then I had a couple of the rocker switches that had gone bad internally. While I remember popping them out to test, sadly I've never found a source of correctly sized replacement rocker switches as modern switches seem to have standardized on a different size. If anyone else has, please post up!

Also you can get electrical contact cleaner in a spray aerosol and apply it through the straw, sometimes the switches have small access holes (or you can very carefully make one with a dremel and a tiny cutting bit) and you can dowse the inside and make them start working. Mostly my success rate with this is pretty low unfortunately, and with closed switches you can't really strip them apart and clean up the contact faces, which probably have carbon from years of tiny arc's when the switch was thrown.

[jcb3cmkdeux]

Yes I do have the black plastic covers and thumbscrews for the fuse boxes although I clumsily broke one in half trying to get it off! Still gives some protection. I hadn't thought about the possibility of 3D printing discontinued parts. That's a pretty exciting concept for machinery restoration.
I'll double check the wiring diagram in the owners handbook, wouldn't surprise me if the rear work lights switch was dicky, the front one sometimes requires abit of rocking to work. Got some WD branded electrical contact cleaner which does a good job. The other day, lying on the cab floor I managed to see up behind the dash. Should be able to give the switches a squirt from this angle.
Just a thought about sourcing replacement switches. We had a 1988 new Holland 8070 combine harvester up until a few years ago. It had an off/low/high type switch for the cab air con fan. It was positioned in front of the driver at forehead height. I do recall it being quite wide. It might be suitable as a replacement for the road lights switch on JCB. Likewise the 8070 had worklight switches which possibly could be similar to jcb's rear and front ones although they didn't illuminate from within. Might be worth seeing if a local combine breaker has any cabs to scavenge.