I been reading on the Internet to how to test the alternator. There are many forums that suggest removing a connector form the battery to see if the vehicle continues to run. I removed the negative cable, the engine ran, but as soon as I touched the gas it died. I removed the alternator by disconnecting the cable and let the vehicle run on the battery and it ran fine, no issues.

Is my problem the alternator.


nash211

 

use a meter and see if the alternator is putting out 14.5 volts.

When you have a weak battery, and continue to drive your truck, the alternator is forced to run with a constant energized field. this weakens the alternator and usually it will go bad trying to keep a bad battery charged.
Some people say to start the truck and turn on the headlights, disconnect the battery then and see if it dies with a load on it.

Best bet is to replace your battery if it is 5years old.They don't last forever regardless of what Sears says.

 

that theres the truth lol,
id agree. try the battery if its old or well used, if the battery is stressed its entire life they could go bad in a year,

a voltmeter is a cheap tool that you will use a lot if you service your own car/truck

 

Yes the alternator is putting out 14.2 volts constant. Is there any way you can test the diodes/rectifiers to see if are fine. The battery appears to be fine, but I did not do a load test.

nash211

 

first off, unhooking a computer controlled motor isn't the safest thing in the world.

Second, if it's metering 14.2, the internals should be fine. That said, is there 14.2 volts at the battery terminals at idle? What about at 2200 RPM's (peak output speed usually)?

 

Yes at idle there is 14.2 volts, and it stays there does not change with increased rpm. I read that either the battery or alternator could cause erratic engine idle at times, correct? Trying to eliminate possible solutions.

nash211

 

replace the batt, or have AZ or orielly's test it on their bench.

 

Thanks


nash211

 

Checked Battery tested fine. nothing wrong. When you disconnect the alternator from the system, and run just off the battery. Truck does not shutter, seems to run better. Hook up alternator, the truck driving down the highway, for no reason just shutters, then runs good again. Tested voltage from alternator 14.2.

I have checked the fuel, changed plug wires and coil. Why does it shutter?


nash211

 

Also, make sure that the alternator is tested for a failed diode. This is an easy test if you have access to a multimeter that can read A/C voltage. Take an ac reading from the output of the alternator to the NEG terminal of the BATTERY.
Anything more than about .05VAC is too much. I've seen cars running over 1 volt of A/C voltage that started just fine, but had all sorts of intermittent drivability problems due to memory getting corrupted.

The bottom line is that modern electronics are EXTREMELY sensitive to voltage fluctuations. Many of the old assumptions about 12v electrical systems no longer hold true. A battery/alternator issue these days will cause problems LONG before the lights get dim when you try and start the car.