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OT- Parasitic battery drain.... how to find the source ? (Toyota forklift)

Milacron

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Dec 15, 2000
Location
SC, USA
Start battery on 2012 Toyota 8 series forklift. Drain is about 4 amps.... have removed all fuses and relays, checking amp meter as each fuse pulled.... with no change in the electron leakage. Now what ?
 
Try a non-contact current probe. It must be going to ground somewhere. This will let you isolate which segment of wiring it is in as you won't see current in the loom beyond the short.
With 4A you might even find it with a IR temp gun.
 
Fuel injected or carb?

Older Toy truck had a carb hot-spot frit that stuck on. But it was via a relay, so you pulled that if you had it.
 
Start battery on 2012 Toyota 8 series forklift. Drain is about 4 amps.... have removed all fuses and relays, checking amp meter as each fuse pulled.... with no change in the electron leakage. Now what ?
Check your key position when you turn it off.
Had the same problem with mine for years, used to keep it permanently on the battery charger when not in use, had numerous auto electricians look in to it to no avail, ended up fitting a battery isolator switch.
Then one day had a guy come to replace a hydraulic hose and he asked why the battery isolator switch, I explained and he just said that we were turning the key all the way off and that far position was for some sort of intake heating element.
Now we just turn it to the first 'off' position and it's all good, no more battery drain.
 
Modern automotive just pulling fuses won't tell you what you want to know. Pull all the fuses and let it set for an hour. Put fuses back in 1 at a time allowing several minutes for the relevant parasitic computer to power up, then check draw.
 
Modern automotive just pulling fuses won't tell you what you want to know. Pull all the fuses and let it set for an hour. Put fuses back in 1 at a time allowing several minutes for the relevant parasitic computer to power up, then check draw.

Not sure if that will be the same on a forklift. But there's an even easier way to check actually by just measuring the voltage drop across the fuses with an appropriately sensitive voltmeter. That method also has the advantage of not waking any of the systems that go to "sleep."
 
As was said above, Get a clamp on amp meter, start at the forklift amp meter and follow each branch. At 4A x 12 V you have 50 W there somewhere which should make a hot spot. Lack of one might mean there are multiple smaller shorts, although at ten years old I wouldn’t expect general degradation of insulation, but FOD is a possibility.
 
Fuel cutout solenoid comes to mind, I had a bad one that was shorting and draining the battery, load test on the fuses, stick ammeter in instead of fuse, usually heater, solenoid etc, current in = current out
Mark
 
Start battery on 2012 Toyota 8 series forklift. Drain is about 4 amps.... have removed all fuses and relays, checking amp meter as each fuse pulled.... with no change in the electron leakage. Now what ?
You have ammeter and pulled fuses.

Left is alternator and maybe engine control unit.

Leave ammeter connected and start disconnecting or unplugging.

Shorted diode will be more than 4 amps, but the field or rotor may be staying active in the alternator.
 








 
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