Got a problem when I have high draw of current when the lights are on the blinker is on and the heater blower motor going the turn signal slows down and the blower motor slows down and the voltage drops to 8 volts and is pulsing in time with the turn signal. Alternator is good brand new battery its a 27dlg 750 cold cranking amps. Grounds are all good fuses good I'm lost help please!

 

like my pappy said "check the easiest and cheapest things first". my first guess is battery. if its over 3-4 year old my bet is thats it.

 

Yes. Your electrical system is powered by the battery. The alternator keeps the battery charged. If the battery is weak, the alternator can't keep up and the voltage drops, especially during heavy loads like you are seeing. Get the battery load tested. Any auto parts store will do this free of charge. No need to be completely lost. Just think about how the electrical system works. It all starts with the battery.

 

The battery is brand new had the alternator checked twice its good. I've cleaned the battery terminals checked the grounds all this is good. Anyone else have an idea what it is?

 

where are you reading the voltage drop? I would read it directly from the battery terminals. If turning the head lights on, immediately drops headlights from 12v to 8v, its a battery. I then would either try another battery or get someone else to load test it. BTW a lot of the cheap hand held load testers are not able to put a proper load on a battery to test it.

 

No I'm going from the gauge in the cab. I'll check the battery again tomorrow. Thanks for the help so far.

 

Here's another tool you can use. I'd not quote its voltage EXACTLY (It may say 12.4 when your battery is at 12.7, say), but it should show trends. And if it's not bouncing around when your voltmeter gauge is, that gives us (There Is No Us) some troubleshooting hints.


RwP

 

The dash gauge is nothing more than a fancy idiot light. Check with an actual tool meant for such things.

 

It turned out being the battery ground to the body was not good enough. So thanks everyone for the helpful ideas to check.

Dudester