Well Guys just another FYI for our 2011 SD 6.7. 190,000 km Came home after a week off and started the truck up via the command start, when I got in it the little red battery icon was lit up on the dash. Well this is my 3rd SD and in the past I always ended up needing an alternator when that light came on. So off to the dealer and was about to replace it, the service rep. stated the alt. was ok and there was something else wrong and it was turning the light on.
So you think here goes my next weeks pay looking for the Needle in a hay stack.
Guys the Teck who is a great guy found a 18 guage red wire that runs from the pass. side battery under and infront of the motor not in any real wire harness and it goes to the alt. had some corrosion forming in under the insulation causing some resistance, and it was telling the system to turn the dash light on.
The teck replaced the bad wire and all is good now.
So fyi guys and it will not cost you $ 505.00 to find that wire. Also you can test the out put of the Alt. and it will show around 15 volts with the truck running even with the red icon on, so you will know it's the bad wire and not an Alt.
Don

 

Same thing happened to mine Don. BUT they did not find the wire until they already replaced the alternator and PCM

I posted the check procedure and wiring diagram here:
https://www.ford-trucks.com/forums/1...l#post12148286

If the dealer would have followed the procedure they would have found the wire BEFORE replacing the alternator and PCM.

190,000, very nice BTW, thats a lot of truck time

 

Just re read your post, mine was a different wire that runs in the same location you describe. Mine was the yellow GENCOM wire that runs from the alternator to the PCM. The one the PCM uses to tell the alternator what volatge to charge at.

 

Hi Darren
The Diesel teck at Koch Ford in Athabasca is Dave, he's been there for over 10 years, and does he know his stuff. Your never going to get it in the ear when Dave is working on your truck. I must admit Carol, the service rep. stopped me from putting an Alt. on the truck, she indicated we should do a quick check of the system before we replace the Alt. Thats the service you get there.
And I will remember your issue if the light comes on again, thanks
Don

 

Thanks for the info Don.
It may be worth the drive to get good service like you did.

 

Well here we go just ran into this exact same problem. A week ago my dash lights started flickering on my dome lights came on and off my center panel went dead and then five minutes later it all came back on five minutes later I went back off. I pulled in to my local napa dealer and have them check the alternator, it was charging at 17 V. I took my truck to their recommended repair shop and they installed a new alternator and two fresh Napa batteries, but the battery light continued to show. I emailed the shop this post any attachments and the pictures showing what previous 6.7 owners had found. They told me they ran all the checks on the wires and could do no further and that Ford would have to diagnose the problem. Took it to my local Ford dealer and they found that the Redwire indicated in these post had corroded through. The lesson here is do your research and mandate that your repair shop checks what u want checked. So my entire repair bill was $1000 for a $.20 piece of 18 gauge wire. Lesson learned the hard way.

 

Hey Missouribear, thanks for the post confirming what I have found. My 2011 6.7 F250 did the same things as yours at 150,000km. Checking the idle voltage, the alternator was at 14.7v. Reading codes found P0625, "Generator Field Terminal Circuit Low" and the Battery light was on. The field terminal signal comes back into the alternator from the passenger side battery +ve terminal via a fusible link (at F151-3, gray), and tells the regulator what the voltage is at the battery. This is then relayed back to the PCM on the GENMON wire (Violet wire on the 3-pin harness C1104A). The PCM then use pulse width signals on the GENCOM wire (Yellow wire on the 3 pin harness C1104A) to tell the regulator what voltage to control to. Sometime this fusible link in the red wire burns, and the PCM loses reference, causing the regulator to max out. It is best repaired by removing passenger side wheel well cover. In other cases the red wire itself corrodes under the engine as it winds underneath and back up the drivers side to the alternator. In any case the red wire from the 3 - pin harness to the drivers side battery can be checked for continuity using an ohmmeter, and should be less than 0.5 ohm (a short ideally). If it is the fusible link, a simple fix. If it is the wire itself (my case) you will have to untape/unwrap it, and clip the zip ties in the protective plastic channels that lead to the other side until you find the break. Splice in a new wire or fusible link as required, and fixed. While your at it, check continuity from the Yellow wire (GENCOM) on the 3-pin C1104A up to Pin 53 of the Left hand side connector of the PCM, C1232B (There's 3 big connectors). Then check continuity from the violet wire (GENMON) on the 3-pin C1104A connector to Pin 14 of the same Left hand connector of the PCM. These two wires route via another connector just below the PCM (C1046), so it's worth checking continuity from there also (Pin 9 and 10)

 

P.S. You can see the plastic trays/guides in darren32s pic above. You can even see a bit of the red an violet wire in the gap. Here is C0146 (the intermediate connector in the GENMON and GENCOM lines, attached to the passenger side battery box) for good measure:

 

This is some very valuable information, thanks for sharing

 

I have a 2015 6.7 with dual batteries and 122XXX miles on the odometer. Got the constant battery light recently. Also had the CEL for the DEF heater, but that is another story. After swapping out with new batteries and replacing the DEF heater the CEL and battery light stayed on. For bonus points the wrench light came on. Everything went out after I cycled the ignition about 5-6 times (short trips over an evening and the morning). I had already made an appointment with my local trusted shop. All is good now.

 

 

 

 

I have the same problem with a 2011 f350 powerstroke, if I am able to dig out the fusible link where would I find one to replace it? Could I use 20 gauge fusible link wire and just run another wire? If I ran a new wire could I go from the drivers side battery or would I have to go to the 250 amp breaker. The cause of the problem was ME, when installing a lift gate I hit the positive battery post with the ground coming from the lift gate. The truck still is charging 14.5 amps at idle but the battery light comes on after 20 seconds after startup. I jumped a hot to the red wire on the alternator and the light go's off and stays off. Any help would be greatly appreciated.

Ted

 

Well I got myself out of this nightmare, Ford said that they would have to replace the entire harness and they couldn't just get the link. I went to the scrap yard and they had nothing. Stopped at a local auto repair shop and the owner (about my age) said hell that's easy enough just cut the red wire and run fusible link wire to the battery terminal on the alternator