Master Cutoff Issue (not alternator!)

Randy · January 6, 2012

After several successful days of driving, I noticed that my voltmeter was below 12 when previously it had always been above when engine was running (charging). Of course I was miles away and with a large group. I split away and hi-tailed it back to camp (Love my GPS!) just as I noticed the lights dim out and the tach start to fluctuate wildly.

Everything pointed to an alternator/regulator problem. Voltage at battery was 11.8vdc and falling even when engine was running. Voltage was present at the alternator. Starter engaged, engine ran, horn worked, etc., just no charge getting to the battery. Turns out that after I cycled the master cutoff switch many times (!) things returned to normal. Weird! Problem never reappeared and I did not touch the switch again to make sure it stayed doing what it was doing.

Two questions - 1) How can the master switch prevent charging but allow all other functions? 2) Do I replace the switch or eliminate it?

Randy.

January 6, 2012

I would think that with the engine running you could disconnect the battery. If the master switch were faulty, it would temperarily disconnect the battery but the alternator which if connected in after the master switch would run everything but the battery wouldn't charge. If you are out on trail, remember that you can easily bypass the master switch by moving the wire over.

Lenny

Randy · January 6, 2012

Thanks, Lenny. Now that I now the problem exists, I carry the correct wrench to do that within easy reach!

Kinarfi · January 7, 2012

When Lenny & I were out one time, Lenny was going along fine until we stopped for a break, that was it for a while, His master switch key had broke and disconnected the battery. He had been running on the alternator only with no battery, I recommend carrying an extra key for the master switch, I made one out of steel, http://www.utvboard.com/topic/1830-dave-needed-master-electrical-switch-key/page__view__findpost__p__7536 I suggest you either get one or make a copy before the plastic one breaks. After rewiring my Trooper, the alternator goes to the start solenoid, then the master switch and then the battery. Not sure how you would lose the alternator and run off battery only unless you alternator just quit.

Kinarfi

iltrooper · January 22, 2012

I too had a master switch problem. I store my T2 in a warehouse so when I was in there I would always start it and let it warm just to know all was well. For no reason one day it wouldn't start. It would roll over only. No spark or injector pulse, (checked with a GM noid) but lights and accessaries worked. Thinking ECM or at least crank trigger I towed it to my shop and started to check things. Why I did it I don't know, but I cycled the main kill switch and it started! Real RELIEF! Now if I could get past my axle problem,,,,,,,,,,

rocmoc · January 23, 2012

I too had a master switch problem. I store my T2 in a warehouse so when I was in there I would always start it and let it warm just to know all was well. For no reason one day it wouldn't start. It would roll over only. No spark or injector pulse, (checked with a GM noid) but lights and accessaries worked. Thinking ECM or at least crank trigger I towed it to my shop and started to check things. Why I did it I don't know, but I cycled the main kill switch and it started! Real RELIEF! Now if I could get past my axle problem,,,,,,,,,,

Welcome! Thanks for filling out your profile. What is the problem you are having with your axle?

rocmoc n AZ