Earlier today I started a thread asking about the quality of the current ford reman'd alternators. In my many hours of research this afternoon I started wondering if I could successfully add a factory dual alternator setup to a truck that did not originally come equipped with one? I'm fortunate in the fact that I have a truck in my possession that came from the factory with a dual setup. Quickly glancing between the two trucks this afternoon everything seems to be plug and play.

Here's what's needed:

Dual alternator bracket: F8TZ-10A313-AA
Idler pulley for bracket: F8TZ-8678-FA
Alternator bracket bolts(2): N606068-S437
Alternator bracket/battery cable stud: W701844-S309
Alternator mounting bolts(3): N606068-S437 (same bolts used to mount the bracket)
Second alternator wiring harness: F81Z-14305-CA
Secondary lower alternator: 4U2Z-10V346-CLRM
Dual alternator belt: F8TZ-8620-GC

Most of these items can still be bought from both fordpartsgiant and tasca. The only item that I can not find is the wiring harness F81Z-14305-CA.

As far as the harness goes I think I could make this. The only thing I would need is plug ends. There is a plug on both trucks between the inner passenger side fender and battery right next to vacuum pump reservoir. On the truck NOT equipped with dual alternators the plug terminates into a "dummy" plug. On the truck equipped with dual alternators this same plug connects into the above mentioned harness F81Z-14305-CA and runs over to the starter relay/solenoid on the inner fender and then down to the secondary alternator. There is absolutely no other wiring involved.

There is one question however that I cant find the answer to. From what I understand the PCM does not command the secondary alternator until the glow plug relay has shut off. I believe it does this to protect the glow plugs. So, here is my question..on a truck that did not come equipped with a dual setup does the PCM need to be reflashed? I can't find an answer to this anywhere. It makes sense that it might need a reflash but I honestly have no idea. The reflash would stop me from pursuing this any further. Thoughts?

 

I guess the question is WHY? The 2 alternator setup presents issues for maintenance and there’s literally hundred of thousands of single alternator trucks that run great. Just curious why you want the second alternator …?

 

tI've read where many people and even ford had come to the conclusion that the single 110 amp alternate was way underpowered for its application. I am by no means complaining about mine btw. Very happy with it thus far. Anyways, fords answer was to add another 110 amp alternator to the equation in order to bump up the idle amperage. One might say "why not run a higher output single alternator"? Well, in my research the higher output single alternators pose a threat to the glow plugs. Apparently the higher voltage the glow plugs see while they are activated can cause premature failure. The factory dual setup allowed for increased amperage while keeping the glow plugs happy. That's it in a nut shell basically. Y2KW57 has WAY more info on this subject than I. I simply found it very interesting.

 

I would suggest a high output alternator (if you think it's necessary) and replace glow plugs every 100k would be cheaper and easier than adding a dual alternator.
I happen to have a dual alternator setup so I can't say what the drawbacks of not having it are, but My truck doesn't sit around idling that much anyways.

 

In addition to the initial cost for installation you now double the maintenance costs. I will tell you that it's a PITA to work on the lower alternator (install/remove), not to mention that you now have to remove the belt and loosen the lower alternator bracket to get your EBP tube in or out.

Mine came with two (like kbeefy) and when my charging system was on the out I replaced both alternators with ones from here: https://alternatorparts.com/

I upgraded to the 6G case and stayed on the lower end of the output (140A) since I was getting two (https://alternatorparts.com/6g-serie...lternator.html). There was very little modification to make the larger cases fit (some grinding/filing on the inside of the bracket).

I agree that the 110A units are a bit small for the truck but I never worried since I had two of them. I also agree with kbeefy about just getting a higher output single. If it were me I would get a higher output unit for your single and call it a day (160A or more depending on how much added load you've installed over OEM).

They came with the truck and I loved my duals...until I had to work on or around them. 10 minutes to change the upper alternator and several hours to change the lower (I had to go in and out through the wheel well on my 4wd).

Just my .02

 

I echo other's comments about the unnecessary complication of dual alternators. Just go with a higher output large case 6G like one of these:

https://alternatorparts.com/6g-serie...lternator.html

 

I will more than likely go with a HO single as it is more cost effective. Not to mention the ease of maintenance/replacing.

I DID however answer my own question in regards to the PCM programming. The answer is...I DO NOT believe the programming matters. I dissected the secondary alt. harness on the 2001 truck. I traced the wires of this harness from the secondary alt. to the plug that sits between the fender and battery. There are three wires that make up the secondary harness. One large 8ga. wire that runs from the back of the secondary alt. up the starter relay on the inner fender. The other two smaller wires come off the two wire pigtail on the back of the secondary alt. and run up to the main pigtail/harness between the inner fender and battery. I then unplugged the secondary harness from the main harness (truck side) and found the two pins on the main harness that correspond to the two smaller wires that run to the back of the secondary alt.

I took several voltage readings off these two pins with the KOEO and found that with the GPR activated the voltage to the secondary alternator was limited to 10volts. Once the GPR kicked off the voltage rose to the appropriate amount. This just verified that the secondary does indeed reduce voltage (just like the main alternator) when the GPR is activated. Once I was satisfied with the info. I gathered from the 2001 I stepped over to the 2000 (truck in question).

All I had to do with the 2000 was test the same two pins on the main (truck side) harness. Since there is no secondary harness on the 2000 the main harness just terminates into a dummy plug on the inside of the fender. Long story short I got the same readings on the 2000 as I did on the 2001. Almost seems like the secondary alt. just piggy backs off the main alt. signals (?) That leads me to believe that PCM reflashing is maybe not needed.

Other than making my own harness (not hard at all) I think it would work. Anyways, it intrigued me...I get bored easy LOL!!!

 

Do you have a link or two with this information about the voltage being limited by the PCM during GP operation? I have never heard of this and it doesn't make sense. Could it be that the high draw of the glow plugs is simply sucking the system voltage down? Remember when current in a circuit increases voltage will drop. Did you try a high idle voltage reading while the GPs were energized?

 

https://www.ford-trucks.com/forums/1...get-along.html

My bad. I knew that. Maybe didn't convey it well. The PCM controls the amount of time the GPR is activated based on temp. Not the voltage it sees. The drop in voltage is due to the major power draw from the glow plugs. Somewhere in the link above it says that the secondary alternator is not called upon until after the GPR shuts off. Now I didn't observe this on the 2001. Just a drop in voltage due to the power draw. Now I'm not sure what I proved.

 

I looked into dual alts at one point and it seemed like way more headache than it's worth. The single 110 alternator has been fine for how many years on your truck? Get that or the Bosch 6.0 140a and call it good. The way the second alternator works, it's not really a backup anyway. It's an odd configuration that only works sometimes. If your main alt fails, as I understand, you are still ****ed.

 

Thanks for that link, what an informative read! I am still running my stock alternator so no worries there, but if anyone is still looking for an automatic solution other than waiting out the two minutes, what about a relay such as what was alluded to in post #64 of the link? My idea is a normally closed (NC) relay connected in series with the GPR ground wire and the other side would be connected to any circuit on the truck that becomes energized when the truck is actually running, not cranking or sitting "ON". This would open the relay as soon as the truck starts and it is a fully automatic solution. My only question would be is there any such circuit on our trucks?

 

Nope, but your tuner-of-choice can shorten the time to whatever you want.

 

You could use an oil pressure switch though pretty easy...lots of places to put one.

 

Any documented proof or evidence that running the glow plugs at full alternator voltage for a brief period is not a good idea? Like a rating from Beru specifying not to put more than a certain voltage to them? Seems like plenty of people have upgraded the alternator on 7.3 engines and not had any problem.

I don’t remember ever seeing any 7.3 PCM designated specifically for dual alternators. Manual/automatic yes. CA/Federal yes. A few other variations also.

 

Makes me wonder as well. The old 6.9 had glow plugs that were rated at 6 volts although their "ON" time was limited to something like 10 seconds and they were very easy to change. If the glow plug relay ever got stuck "ON" the 6 volt plugs would disintegrate resulting in catastrophic engine damage. I put in a dash light in case this ever happened I would know to shut down right away. This in itself proves that over voltage will destroy GPs but like anything else it is going to be related to how much over voltage and for how long.