I brought my truck to a parking lot to set the idle because of noise...

And as the truck was running, I observed the buzzer and cab dome lights lose voltage...

I say voltage because the buzzer would quiet down with the flicker of the lights...

Can the voltage regulator be replaced on the alternator?

Or do I need a whole new unit?

You think this is the alt. or could something else cause this?

Thanks!

 

It is the cold wether getting here my friend. Your grid heaters are starting to cycle on and off. Nothing to worry about. Start it up on a cold morning, and watch the volt meter cycle. You will realize why these beasts come with 2 batteries stock then

Eric

 

Nah, this was very different...

The truck was warm already...

 

ur grid heater could still be cycling though....anyways check all ur connections and grounds...sounds like a loose connection...don't go and replace the aletrnator just yet

 

The Haynes manual for these trucks has an excellent section on checking all the components in the grid cycle circuit. Easy to follow step by step instructions. Well worth the $15.

 

I could be wrong, but less than 18 MPH and less than 56*F ambient air temperature and your grids will cycle even if the engine.

I'm sure some will correct me if I'm wrong.

 

No - that sounds familiar to me, too.

 

OK, I know its not the grid heaters...

Anyone else?

 

Have you checked the amperage draw from the batteries with the engine off? Draw should be .5 amp or less. Expect some current to go toward the stereo and computer. If you're seeing excessive draw start pulling fuses until problem goes away. Now you know what circuit has the short. Current is measured in series. With a single battery setup, remove the negative cable. Configure your multimeter for Amp. Connect one side to battery cable and the other to the battery. This makes the meter part of the circuit. Many meters are not capable of power above 10amp. This is why everything should be off.

 

Its fine...

And it only does it with the engine running...

Alternator?

Does the voltage regulator come with a new alt?

 

The voltage regulator is built in to the ECM. Do a search and you will find the conversion parts and process necessary to install an external voltage regulator and solve the problem for hardly any cost.

 

What is that black box on the alternator?

Could the alternator be going south at 130k?

Would this indicate a problem?

And the lights flicker more under acceleration...

HELP!!!!!

 

Should I take this to the dealer?

Anyone think this is gonna be a serious problem?

Would the alternator do this?

I've been digging around my truck all night looking for a cause...

 

When I had a first gen (a 91) the voltage regulator did go out a few times. It did have symptoms similiar to the grid heaters cycling, but was not the heaters kicking in. Usually when the RPMS were up, the alternator was putting enough power out to mask the problem but at idle, the lights would steadily dim then suddenly brighten back up.

 

The black box on the back of the alt is defiantly the regulator, and yes they go bad.

If you have a meter hook it to the battery at Idle and tell me what it say in volts you should have atlest 14.0 volts.
you can also load it up by turning on all your accessory's on at the same time and checking to see what your meter reads with load on it. (headlights high beam, wipers, radio, heater)


you could also take it to auto zone and have them load test the whole system, they do it for free.


*edit*

If you want to check for a draw pull the negative battery cable and put a test light between the neg cable and neg battery lug, if it lights up you have a draw.
then like mentioned earlier start pulling fuses until the light goes out.