Hello All

Driving truck and lost all electrical power had it towed home.
Replaced alternator with new and new battery also,
Alternator not charging battery,
no battery light with key on
Fuses are not blown
Replaced bulb and socket in instrument panel

Any help appreciated

Much thanks!

Sorry for lack of info this is my first post

2002 ford f150
5.4 V8
checked the alternator charge with a multi meter
At the battery only reading 12 volts as opposed to 14 volts even with some acceleration

Checked orange wire and green wire with trouble light, power to the orange wire no power to the green wire with key on or off.

Connected a jumper at the alternator plug to jump the orange wire to the green wire this provided power to the green wire, however the battery light on the cluster is still off with key on/off with this method.

 

You don't mention the year or any other details of the truck you are working on. With no other information the mega-fuse on the fire wall comes to mind. Follow the positive cable from the battery to the firewall to locate the main fuse. Some years had problems with them breaking internally causing an open circuit.

 

Did you just replace and hope or did you do any actual troubleshooting?

 

Very good point just being a parts changer can be costly How did you check the Alternator not charging battery,. What were your readings. Fuses are not blown What fuse did you check? What was your voltage readings before and after the main fuse. If you are not going to answer the questions asked how do you expect any help? Do you know what truck you have? We sure don't.

 

Sorry for delay didnt have a garage so this project sat on the back burner over the winter. Sorry for lack of thread etiquette as this is my first post on a forum 😊 am trying to get this puppy running over the summer as I have a garage now 😊

I have also updated my original post with truck info and what procedures I have used for testing ect.

 

That is a standard alternator, it is dependent on an exciter current from the light on the dash, so if there is no battery light , key on engine off that would be the first point to rectify..

 

Thank you,

Yes I believe it to be an open Excited circuit as well.

I have replaced the bulb in the cluster, and still no light. I am wondering if I need a new cluster? But I dont know how to test the cluster for this issue. I see no heat Mark's or burns from potential shorts on the cluster board. And it seem ok when I try to test continuity?
However the digital odometer cuts in and out but has been doing that for quite awhile all ready.

 

Yes, it is open. Lt Green wire with red stripe comes from the instrument cluster.

Here is the schematic. We know that fuse F30 is good since the engine starts and runs. You'll need to check to see if power for the I-circuit is getting to and through the cluster to the alternator and where it gets lost.

Edit: Well, it seems the website's upload facility isn't working right for me, I'll try again later.

 

You guys know how that light works right?
When you turn the key on, power is supplied to the lamp on the cluster side
It grounds through the alternator field which is ground before starting the car or truck
That turns on the light
You start the car, the field gets energized, the light now has positive juice on both sides and the light goes out
Knowing the strategy might help you
Find the reason for no (engine off) cluster voltage to that bulb?
Good luck

 

Similar from '16, although a reman alt fixed it for me

https://www.ford-trucks.com/forums/1...ash-light.html

 

Yours passed the indicator lamp test. The OP's truck would fail that test given the information provided. His immediate problem is "upstream" from the voltage regulator/alternator.