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Re: Electrical fault 3126

The alternator has a post for rpm guage on it

Contributor

Re: Electrical fault 3126

my 3126b is doing the same thing. Did you ever get yours figured out? plesse let me know if you got a fix for this.

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Re: Electrical fault 3126

Hi Dave,The voltage is fine 27.5 volts when running.its an alarm fault thats common to the tachometer,Regards Mark

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Re: Electrical fault 3126

I will assume this is not an electronic engine. The 3126/3126B is equipped with an intake heater that draws a huge amount of current (100+ amps) when active. Intake heater is on when engine coolant temperature is below about 125F. It's normal for voltmeter to be below 12 volts when the heater is on. Also, you may need to increase the engine speed to above about 1400 RPM right after starting so the alternator starts charging. Then, idle should be at least 700 RPM. Once the heater turns off, the voltmeter will display normal voltage (13+ volts).
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Electrical fault 3126

I have a 3126 cat in my charter boat rated at 375 hp.when i start up the alternator light stays on and the tachometer wont function,after a while the light goes out the tacho springs to life and all is ok for a while until the same thing starts again.the voltage is good,batteries are new,changed alternators made no difference,checked all the wiring,any ideas?