Intermittent Variable Speed Signal Flashers/Tach

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a3inverter
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Intermittent Variable Speed Signal Flashers/Tach

Post by a3inverter » Tue Jun 13, 2017 11:13 am

All,

Took my 1973 bus out for a spin this morning and about 15 minutes into the ride I noticed my aftermarket tach needle bouncing around with no relation to engine speed. Also noticed that when I turned on the turn signals, they were flashing at a higher than normal speed (but not the super fast of a bulb-out situation). Finally, noticed that the display of my dakota digital cylinder head temp gauge was pulsing ever so slightly (not the flashing that means you are running too hot).

This behavior came and went throughout the drive and the speed of the flashers seemed to vary from time to time...normal...then too fast...then too slow.

I am going to tighten up the alternator belt this afternoon as it's on the edge of too loose, but it's been that way for a while and this is the first time I've encountered this issue.

Any thoughts?

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airkooledchris
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Re: Intermittent Variable Speed Signal Flashers/Tach

Post by airkooledchris » Tue Jun 13, 2017 1:29 pm

Sounds like electrical gremlins. I would be surprised if it was related to the alt belt, but it's worth a shot. Check for any loose wires behind the dash and look at all of your fuses. Wherever the CHT gauge is getting it's power from - look to see what else is sharing this power source. Maybe there's a loose grounding terminal that you have some devices sharing.
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sgkent
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Re: Intermittent Variable Speed Signal Flashers/Tach

Post by sgkent » Tue Jun 13, 2017 3:09 pm

I might ask myself of the voltage regulator is going bad, or maybe there is a bad connection at the battery. Put a voltmeter across the battery terminals using long leads so you can avoid being near the belt, and watch it for a few minutes. See if the voltage is stable or bouncing around. If it is bouncing it may be the VR going out. The old style used points that opened and closed. Those eventually get sticky. Another test is to put a load on the system like turn on the headlights and then see if the bouncing gets worse or gets better.

As Chris said - you could have a bad ground or bad connection anywhere in the bus from the battery in the back to all the way up front to the dash.
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a3inverter
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Re: Intermittent Variable Speed Signal Flashers/Tach

Post by a3inverter » Tue Jun 13, 2017 4:41 pm

Thanks all!

Drove home from work this afternoon with no issues. Strange stuff. Will check out my grounds, the power source of the CHT gauge and tighten up the Alt belt a little bit just because.

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