Hey guys...

So, I’ve been searching the forums today trying to look through all the stuff TooManyToys and others have posted (and even responded to previous posts of mine in the past), but while I’m still trying to wrap my head around all that, here’s what I’m dealing with:

- went out to the truck yesterday (plugged in overnight). Started it up fine, but as I was about to drive away, I noticed my voltage was low (~11.8). I pressed on the connectors on my main alternator as that has *seemed* to help in the past, but no go. Turned the truck off and took the wife’s car to work.

- today, went out to try again, had forgotten to plug it in overnight (~37 degrees outside). Tried to turn over, but nothing and didn’t want to stress the battery, so wife’s car again today.

- get home tonight (had my wife plug it in a couple hours before I got home as temps are in the high 40s low 50s), started the truck. ~11.5 volts again. I let it run for a bit this time based on what I had read about maybe the glow plugs taking a lot of the voltage, but no change. Even dipped down and was fluctuating between 11.3 and 11.7/8 volts.

While the truck was running, I checked both batteries with a multimeter. Passenger: 14.something volts. Driver: 11.6 volts

Turned the truck off and checked voltages again. Passenger: 13.9 or 13.09. Driver: 12.26.

Oh, and FICM was 47-48v the whole time.

My first inclination is that my alternator is going again? But it’s a Bosch that’s just over a year old... I also am *fortunate* enough to have a second alternator (makes removing/installing the primary one lots of fun...). That one is quite possible the original, but I’m not sure. So....while I’m trying to read through all of these posts, any other suggestions? I drew up a fancy diagram to help explain the above

Terminals aren’t spotless, but there’s no real corrosion I can see. I’ll still pull them off and clean them though just in case.

Anyway...thanks in advance, everyone.

 

Can you get some pictures of your battery terminals? And does your meter check ohms or continuity?

What your diagraming and saying sounds like you have a disconnect or issue between the two batteries. The forum has had threads before of this issue. The truck starts off of and charges the passenger battery, but the poor or no connection between the two batteries positive, or even negative, means the drivers battery supplies the system voltage, but it never gets the charge it needs.

 

Glow plugs are also powered off the passenger battery, so any monitoring of the drivers battery would not show any on to off swings if the batteries were isolated.

 

Driver positive


Driver negative


Passenger positive


Passenger negative


Meter does continuity (the one I used for the previous tests is a normal leads-type meter) Just bought it tonight to troubleshoot so I need to figure out how to do that, but the package says it can. Lol.


I have both types of meters so pretty sure I can measure continuity and resistance.

 

Those cables at the passenger's positive terminal are looking pretty rough.

 

Pull the negative terminals on the batteries, check for continuity positive post to positive post, including moving the cables.

There are other ways to do this. I’m trying to do it the safest. If you can have a poor connection, and that may be at the pass positive terminal, but it may only show at current flow.

 

I punched up your one pic.




i really think you may find you need to replace that main positive cable assembly

 

Alrighty. I don’t want to jump to conclusions, but I think I may have found the culprit.

when I first connected the meter, I was getting nothing. So I wiggled the pass and driver cables. Upon wiggling the pass side, the wire that runs across the front of the truck connection was loose (wire inside the connection, not the connection itself). Looking at it closer, there are definitely some frayed/split wires in that cable. So I’m guessing a replacement of that is in order.

When I started it up, I’m reading over 14v on the scangauge.

bonus: my FM radio works now! Lol.

 

If the battery cable is the culprit, it's best to charge both batteries with a battery charger before connecting everything again. The second battery is depleted. I always charged my batteries at the same time. It's a good idea to do this once or twice a year even if you are not having problems. Both batteries on my van were located on the frame rail. Ford did something intelligent and added a large positive plug for charging/jumping on the frame rail.

I had the Bosch alternator as well. My 6.0 is in the hands of a retired military combat veteran with time on his hands to tinker around.

 

Yep, that would be the crossover cable that connects the two batteries.

That's part of a complete harness from Ford, battery to battery, then down to the starter. The alternator connection bolts to the top.

So someone was in there due to that connection failing and modified the terminal and cables. There are two routes you could go, modify and replace some of what you have, or replace all of it with a new Ford cable. I'll tell you right now if you want the factory Ford cable, the best price is from RockAuto.

The other method you could do since someone has put on an eyelet to the starter cable is to leave that alone and replace everything else. the quandary would be, is that starter lug good. If you think it is the easiest way is to replace the terminal with a "military" terminal, and get a replacement positive cable from the driver's battery to the pass battery military terminal. That would be a 70" 2/0 cable, lug to lug and put a military positive terminal on the driver's side too. You will have to enlarge the lugs on the existing alternator cable and the CJB cable on the driver's side.

 

So that’d be this guy here, yeah?



Looks like it’s out of stock via rock auto. Other places seem to have it for 80-100 though. Is it significantly cheaper on rock auto?

Also, if I went the route of just changing the terminal to terminal cable, what do you mean by enlarging the lugs? Cutting the wire and attaching larger connectors? Just trying to make sure I understand.

Thanks!

 

When I bought that exact cable last it was $84 on RockAuto. If you can get the cable for around that it's a good deal.

The existing lugs should be for a 6mm (1/4") bolt/stud. The military terminal bolts will be 5/16", which is 8mm. You would have to drill or file them to open the size.

The stock batteryto battery cable size is 2 gauge. I told you 2/0, a typo, but you should use a 1/0.

 

Awesome, thanks!

 

I have found tapered reamers to be the safest, and sometimes fastest way to enlarge a hole in thin metal.

 

Good point Chris.