Non P6 electrical issue

Well it's that time of year again (if it dries up for long enough) to start getting some veg in the ground so I need the row crop tractor sorted. I went through the remains of the loom, alternator, solinoid, ignition switch etc and could find no short circuits. A neighbour tested the alternator and found that the regulator had failed. It showed no signs of internal fire damage but was pretty badly corroded so I decided to go for a new ARC 17, new battery and I made a new loom from scratch. The alternator I got had been fitted briefly to another tractor and then returned as faulty (the ignition light stayed on). He tested it, output was perfect, and as it was the only one he had I took it. I fitted it and fired it up but the ignition light is staying on. It's charging fine, and rather than go to the trouble of removing it, swapping pulleys again etc I want to fix the problem if it's an easy one. Any thoughts? When I rewired the ignition light I took a feed from the ignition switch to the lamp, and wired the other side to the small terminal on the alternator.
Regards,
Dave
 
if you've taken the supply for the light from the "ignition on" terminal on the switch then you've wired it correctly, and as you've made a new loom I doubt it's shorting to earth between the ignition switch and the alternator, so it's an internal fault in the alternator itself. ACR's won't charge if the light isn't working, and if the light is staying on I can't see how it's charging.
 
harveyp6 said:
if you've taken the supply for the light from the "ignition on" terminal on the switch then you've wired it correctly, and as you've made a new loom I doubt it's shorting to earth between the ignition switch and the alternator, so it's an internal fault in the alternator itself. ACR's won't charge if the light isn't working, and if the light is staying on I can't see how it's charging.
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I'll check it again harvey, light is definately wired correctly and I did point to point tests on the loom before I fitted the battery. I hit another issue and had to shut down before I could do any further checks.
Regards,
Dave
 
Ok, tested the battery voltage today and only had 12V with the engine running. Pulled the alternator off, went down to the neighbour I got it from and had him tested. He stuck it on the test rig and ran it up gradually. The warning light went off at 400 RPM and stayed off all the way to 4000RPM. The voltage looked fine and applying a load of 15 amps caused no issue. Took it back, refitted it and fired up. The ignition light went off straight away at idle. Shut down and went off for a coffee. Can back, fired it up and the light was there again. I disconnected the warning light cable with the engine off, ignition on, and the light went out, hence no short. I guess the alternator has an intermittant fault. Been through the entire loom and everything seems fine. I've workied on auto electrics on every thing from Fiat X1/9s to Volvo FL10s and the worlds most basic loom doesn't want to work for me! Having said that I've had very little to do with charging systems other than swapping out alternators. Below is a diagram of the loom.

022ts.jpg


Regards,
Dave
 
It could be that the alternator isn't spinning fast enough, it's likely being a tractor you are not running at many revs, try opening the engine up to kick the alternator into life.
 
Rubythursday said:
It could be that the alternator isn't spinning fast enough, it's likely being a tractor you are not running at many revs, try opening the engine up to kick the alternator into life.
Click to expand...

Or put a smaller pulley on the alternator.

Colin
 
Gents,
I've done both. The alternator came fitted with a small pulley when I got it so I fitted it up with this first and tested it, but the V belt was far too deep for it. I refitted the original (which I assume came off the dynamo originally fitted). The original alternator always charged fine with the larger pulley, and indeed it charged at idle yesterday when I first fitted it after testing. The entire loom and battery are brand new as well. The sawmill next door have alot of old loaders thrown about so I'll borrow an old alternator and swap it out to test it. I think the new one must have a dodgy internal joint. At least everything mechanical seems fine! The engine is running sweetly, hydraulics worked fine and we'd recently rebuilt the brakes. As soon as I have the issue sorted, and the veg planted, we're going to degrease, repaint and fit all new tin work (front panel, foot plates, bonnet and mudguards), exhaust, pre cleaner and lights, seat as she's looking a little rough as you can see below! uckily parts seem to be very cheap, and after 35 years making drills, planting, spraying etc it deserves it. The modern tractors are just too big and akward for this work.

019akr.jpg


Regards,
Dave
 
022ts.jpg


What does the wire from the bottom of the ignition switch do to the starter when the ignition switch is closed? Something looks a bit cockeyed with that diagram. If the starter has a manually operated solenoid then why link the ignition warning light supply through the starter terminal, and if its an electrically operated solenoid where does it pick up its supply?

Something just doesn't look right to me, whether that's because it is wrong, or because I've misinterpreted your diagram, I can't be sure.
 
When swapping a generator for an alternator on a tractor, the often made mistake is the
slower rotation of the tractor engine, particularly a Diesel like that one. A smaller than
standard pulley will keep things spinning nicely.
 
An alternator is designed to run at up to about 12,000 rpm so ideally the pulley should be sized to achieve this at the maximum engine speed, for example if the maximum speed of the tractor engine is 4,000 rpm, then the alternator pulley needs to be a third of the diameter of the crankshaft pulley.
 
harveyp6 said:
What does the wire from the bottom of the ignition switch do to the starter when the ignition switch is closed? Something looks a bit cockeyed with that diagram. If the starter has a manually operated solenoid then why link the ignition warning light supply through the starter terminal, and if its an electrically operated solenoid where does it pick up its supply?

Something just doesn't look right to me, whether that's because it is wrong, or because I've misinterpreted your diagram, I can't be sure.
Click to expand...

Harvey,
the starter is operated with a lever. This engages the gear when you push it, and closes a low current set of contacts to supply power to energise the solinoid. The cable from the ignition switch goes to this contact. The reason the warning light ignition feed comes from here rather than directly from the ignition switch is simple, I ran out of ring lugs with a 12mm hole! The ignition switch fitted is actually a spare battery master switch we had knocking around in the workshop when the old one failed.

Gents,
I'll check the diameter of the crank pulley. I did have the original pully that was on the alternator fitted, but to no avail, and the previous alternator charged fine, with the large pulley. However, I wasn't aware of the speed they were designed to operate at. The tacho has never worked (it would have been mechanically driven off the rear of the dynamo) but as far as I'm aware max revs are approximately 2200/2300 RPM. It rarely gets above 1500RPM when it's working.
Regards,
Dave
 
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