Charging system down, no start

[Wyo6.4KingRanch]

Alright so the Ford dealership had my truck for a week and I got it back a few days ago. Prior to going in I only had a code for the 4X4 vacuum solenoid, and turbo circuit performance. However, it now being a week later it has gone to complete sh!t. My battery light came on first then I changed my H&S to monitor voltage and it floated at 13.8. Watched it for another day and the next morning I drove to work only to watch voltage drop below 10 the way out and the ABS light flash on and off. Right before I turned the truck off so it right at 9. Afterwards I went to fire it up and got slight crank and no start. Got a jump from a friend and got it started. After about 10 seconds headlights turned off ( left first, then right) then I lost all power to the dash and watched the voltage drop to 7 volts and killed the truck. Throwing a lot of codes before I cleared them and will post them once I get back out to it. Any ideas? I was thinking PCM/ECM?? Would it help to redownload tune from programmer?

 

[DiehardFordguy]

I may have missed something... But alternator? Low voltage causes all kinds of wacky codes.

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[Diesel23]

I'm with diehard ford guy ,think it's your alternator

 

[Powerstroke Man 6.4]

Alright so the Ford dealership had my truck for a week and I got it back a few days ago. Prior to going in I only had a code for the 4X4 vacuum solenoid, and turbo circuit performance. However, it now being a week later it has gone to complete sh!t. My battery light came on first then I changed my H&S to monitor voltage and it floated at 13.8. Watched it for another day and the next morning I drove to work only to watch voltage drop below 10 the way out and the ABS light flash on and off. Right before I turned the truck off so it right at 9. Afterwards I went to fire it up and got slight crank and no start. Got a jump from a friend and got it started. After about 10 seconds headlights turned off ( left first, then right) then I lost all power to the dash and watched the voltage drop to 7 volts and killed the truck. Throwing a lot of codes before I cleared them and will post them once I get back out to it. Any ideas? I was thinking PCM/ECM?? Would it help to redownload tune from programmer?

Check for codes sometimes they will throw codes if something wrong with the charging system.

 

[Wyo6.4KingRanch]

I may have missed something... But alternator? Low voltage causes all kinds of wacky codes.

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Have checked codes, i think all relate to fuel. I thought alternator, but why would it cause the ABS light to freak out and flip on and off? also why would the battery light come on but the truck stay at 13.8 for two solid days of driving if it was the Alternator?

 

[DiehardFordguy]

I had a similar problem on a 6.0 ended up being the pigtail on the alternator. Did you figure it out by now?

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[Dzchey21]

I think you have a loose connection somewhere. I would start at the passenger battery and make sure everything is clean and tight over there. that is where the alternator connection is. I am unsure exactly where the ECM gets the signal from for the readout on the gauges. I would check actual voltage with a meter at the battery and make sure it matches the voltage the computer is seeing. I have a feeling you have a bad connection because of the jump start issues. The alternator might put out enough but if the connection at the battery cable is not good it wont actually keep the ECM's going. I have also seen some alternators start to burn the main cable connection at the back of the alternator.

 

[Wyo6.4KingRanch]

Turns out it was a combination of alternator and he vss connection at the rear diff. Ford muffed the connection during a service. I fixed it all now and will be back on the road Monday. Thank you everyone for your input. You guys were much more helpful than the parts store people