Battery Dummy Light Is on

[Schondo]

I have a 2001 F-250 7.3, the battery dummy light came on and has generally stayed on but it will flicker off from time to time. The guage shows that the voltage is in the right area and has never changed from what it was before the light came on. Any ideas on what this might be and/or how to fix it?

 

[dustinz85]

alt maybe going bad, you can have it tested at your local parts store

 

[SDS97_7.3]

I've had it come on for the alt going bad and for the sensor on top of the alternator coming loose.

You can test the voltage at home with a voltmeter and see what it's putting out first before pulling it and taking it somewhere.

 

[Arisley]

The connector at the top of the alternator, the one sticking straight up. That is Battery power. Check to make sure that connector is tight. Sometimes the connector itself will break and the heatshrink will hold it together making it look like it is getting a good connection.

 

[Schondo]

ok so I checked the output and under a load(ie the air on, radio on and the lights on) it is putting out just over 12v

 

[Dantheman]

Should be around 13.6v

 

[lincolnlocker]

13.6 is even low. at idle on the back/top of the alternator, where the shrink tube is, measure the output voltage... should stay at or above 14v. 14.2-14.3v is the norm at that connection. check all grounds too.

live life full throttle

 

[Lang]

ok so I checked the output and under a load(ie the air on, radio on and the lights on) it is putting out just over 12v

Mine started this yesterday! This how you check it under load? Or does it need to be pulled and brought to a shop?

 

[Atsah]

Just put a volt meter across each battery engine off, should read 12.5 volts or so.. At an idle, battery's should read in the 14V range if the alt is charging correctly..

 

[lincolnlocker]

^^^that too

live life full throttle

 

[Lang]

Just put a volt meter across each battery engine off, should read 12.5 volts or so.. At an idle, battery's should read in the 14V range if the alt is charging correctly..

Couldn't you have the voltage but not keeping up with the amperage? I was reading it has to be under a load to test... Or is that incorrect?

 

[lincolnlocker]

let the truck sit over night and before you turn the key check battery voltage. if its below 12 with key off they are bad. with key on engine off it will draw down cuz glow plugs are activated but i dont think it should get below 10.8v or something. then after its been drove for a little while check idle voltage. should be back up to or a hair over 14 volts...

with key on engine off thats where you will get your load test with the glow plugs activated.

live life full throttle

 

[Schondo]

I just wanted to say thanks to all, I changed the alternator yesterday and we are good to go for now.

 

[Lang]

let the truck sit over night and before you turn the key check battery voltage. if its below 12 with key off they are bad. with key on engine off it will draw down cuz glow plugs are activated but i dont think it should get below 10.8v or something. then after its been drove for a little while check idle voltage. should be back up to or a hair over 14 volts...

with key on engine off thats where you will get your load test with the glow plugs activated.

live life full throttle

Copy. It was it. Thanks for help!