I don't get melt temps either, but I don't make the rules

Pretty picky myself about electrical connections, in theory it's a great idea though solder is almost never used for high current applications?

Maybe silver solder would be OK it has a lot higher melt point. Brazing should work.

"Alloys that melt between 180 and 190 °C (360 and 370 °F) are the most commonly used. Soldering performed using alloys with a melting point above 450 °C (840 °F) is called 'hard soldering', 'silver soldering', or brazing."

 

I worked on the wiring all day today. I actually made progress. I focused on these two metrics:

1. I had a voltage drop of .675 volts from the alternator to the battery with AC on, rear def on, high beams on and the fan on high front and back. The only components between the alt and the battery on the B+ wire are the glow plugs (GPCM for me), the AIH (Deleted/defeated for me) and the starter solenoid. My GPCM is fairly new, the starter solenoid is brand new (as are the fusible links). The AIH is still hooked up, but it doesn't do anything.

2. I had 6.5 ohms of resistance between the negative battery terminal and the alternator case. It shouldn't be that high, even though that might seem insignificant.

I traced the black/orange wire from the alt through the harness. I opened the harness up and looked for chaffing or burns. I did't find any evidence of problems, but I also didn't open up the splices for the two GPCM off-shoots or the AIH splice. They could possibly be problems. I cleaned the ground on the drivers side block really good and got the resistance down from 6 ohms to 4 ohms. Progress!

I bought the following items at a car audio shop in Austin:




2x150 fuses




Fuse block




17 feet of GOOD cable

I also bought about 3 feet of black ground cable just like the red one. High quality stuff...pricey. I installed it like so:





short ground from battery to case




grounded to the cable itself




doubled up the cables on the B+ terminal




Routed about the same as the original without the outgoing branches for components




Fuse block and termination at starter solenoid.

So, the results were:

- I now only have a .175 voltage drop from alternator B+ to the battery +
- resistance between the battery negative and the alternator case is now less than 1 ohm.

Still drawing 53 amps at idle with all the above stuff turned on, but voltage drop reduced drastically. I have 41 amps running through the new red cable, and 12 amps running through the old black/ong cable. That clearly tells me either the GPCM or the AIH relay COULD be a problem, since electricity takes the path of least resistance. I tried unplugging them each one at a time, but I was unable to detect a difference in readings both before or after install of the new cables. Any more ideas going forward?

 

[QUOTE=Tedster9;16410010]I don't get melt temps either, but I don't make the rules

Pretty picky myself about electrical connections, in theory it's a great idea though solder is almost never used for high current applications?

Maybe silver solder would be OK it has a lot higher melt point. Brazing should work.
QUOTE]
Solder is not allowed in Any Commercial/Industrial or residential wiring, because it failed and caused fires

 

Makes sense. I went through (after shutting breakers OFF) the main electrical service entrance box to our home, and the furnace/AC connectors, they use a kind of screw or clamp deal on the Romex and other wiring. Over the years these can loosen slightly. One thing working on trucks (and everything else) has showed, it doesn't matter WHAT you're working on, neglected grounds and connections always cause problems. Clean and tight. Important. Some recommend checking electrical outlets as well. We now return you to the regularly scheduled discussion.

 

Made a significant discovery today. I was cutting off the pigtail I had crimped on last year when the first alternator got so hot it cooked the insulation of the B+ wire. I had to cut that wire back about 8 inches to get to good insulation, and I attached a battery cable to the remaining wire and used that to hook to the B+ lug. Well, I went to replace that pigtail with my good quality red 4 AWG I had bought a couple of days ago. I peeled back the tape and exposed the splice. It was burned pretty good. I cut it off, and I peeled back the insulation again to make a new splice to the new wire, and I found the copper in the stock black/orange B+ wire is very, very corroded inside. I checked a couple of other places along the B+ wire, and I found more green copper.

So, it looks like I have fallen victim to corrosion and that has likely been my main problem all along. I found other things that needed attention, but I am betting the corrosion is the root of the issue. I am going to have to cut open the harness completely and replace ALL that B+ wire, plus splice in the GPCM and AIH pigtails. Fun, fun, fun.

 

Yup that will do it. PITA to fix, but good find.

 

After I replaced the burnt splice and the pigtail, I now have reduced the voltage drop from the alt to the batteries to .075V. That is down from .675V. What this means to the average guy who doesn't play with multi-meters often is: I eliminated some resistance to the flow of electricity (current) from the alt to the batteries. This manifests itself as heat if the resistance is high enough.

To get the voltage drop to 0 (where it should be), I need to replace all the old B+ wire. Technically, I have gone around it (in parallel) with the new red 4 AWG, but that should not be a permanent fix since I know the wire is corroded. When trouble shooting, Ford's manual says a voltage drop under .5V is acceptable, but I have to respectfully disagree on that.

 

That's a huge difference.

Six hundredths of an ohm (hardly anything) resistance in the alternator circuit reduces alternator output by nearly 30%! This is why testing for ohms is normally not done, because unless one has a baseline measurement there's no way to tell if it's gotten worse, plus 0.06 ohms is just a rounding error in terms of DVOM accuracy. Thus the voltage drop test.

For some reason the acceptable limits are a little bit higher on the positive side than negative. It depends on what circuit too, starter, headlights, charging, etc. The limit of 0.5 tenths is a cumulative one however, usually 0.2 on the negative side.

In the instance described here with the alternator, it's not enough to notice at idle maybe, but under any kind of load it will simply not be able to keep up. I would expect maybe some people who spring for higher output alternators all they probably really needed were some new cables and clean up the main grounding points. High resistance also "fools" the alternator into thinking the battery needs charging, this will lead to excessive battery outgassing and probably hard on the regulator.

 

You bring up some great points there, Ted. My batteries have been out-gassing for some time since the alternators started dying en masse. Also, my alternators stay very hot to the touch, which indicates they are staying on too long and working too hard (thinking the batteries still need charging due to voltage drop?)

Ford says to check the voltage drop from the alt to the batteries with "everything" on and the engine RPMs at 2000. If under .5VDC drop, then the alternator is "supposed" to be the problem in that step of the testing if system charge voltage is low (< 13 VDC). If above .5VDC drop, Ford says to repair the wiring if system charge voltage is low. In my case, I need to repair the wiring (corrosion).

I think I might just cut out the old cable and move the pigtails for the GPCM and AIH over to the new 4 AWG cable. That way, it will be much easier to access in the future, but if I do this right I should never be chasing this problem again.

 

For some reason when you mention voltage drop I somehow (maybe wrongly) get the impression you are referring to the total drop across both battery terminals? That isn't how it's performed. Or at least for the benefit of others who are following along you should try to be more clear because it's a common mistake. In any case you're doing a good job illustrating how important preventive maintenance is, it pays for itself.

Electrical bugaboos can quickly get into serious buckage for attempted repairs these days.

Yes, the charging system can get into a kind of negative (heh) feedback loop. For example, leaving lights on overnight. Older trucks didn't have protection for this sort of thing. So the battery is dead. Auto start batteries can handle being discharged only a very few times. A bad cell or defective battery can ruin in turn ruin an alternator or VR. Corrosion will tend to cause excessive outgassing and heat, even just a dead battery presents a tremendous load and can roast diodes or the alternator stator.

I even thoroughly charge new batteries before installation, the idea here is to pair a serviceable battery with a serviceable alternator and everything in between at all times. The battery really has only one purpose, is only to start the truck. It sort of acts as a filter or a sort of voltage regulator smoothing out spikes and sags. But the alternator provides all the juice for the ignition, lights, and accessories. We want to provide clean power to all those sensitive computer chips and sensors and I don't know what all, and not get them zapped by loose or missing grounds, corroded connections etc. A dirty power supply kills $$ parts Every. Time.

 

I am talking about the drop from the B+ lead to the positive battery terminal on the driver's side. It goes like this: Negative lead on the + battery terminal and positive lead to the B+ output from the alternator. Then turn everything on and have someone hold it at 2000 RPMs.

 

So I think someone had done this to my EX before I bought it, but did not do a good job. I have been "fixing" glow plug and GPCM problems. I just realized the factory Cable running from the alternater to the starter relay was disconnected from both ends. so really probably all 3 GPCMs I have tried are all fine, just never recieved power. Do you have any pictures of the pigtails to GPCM / AIH? As a temp fix could I run reconnect the factory wire at the starter relay and leave the other end disconnected from the alternater?

 

You are in luck. I just finished up the changeover last week. I will post some pics later today when I wake up.

What is coming off the B+ on your alternator right now?

 

This is what is going on :
In my left had is the factory wire from the alternater and is disconnected (it actually was taped to the new wire to keep it from moving around)
New cable attached to alternater (factory one still disconnected)
Routing of new cable on top of engine (similar to your squiggly line drawing)
Routing of new cable on top of engine (similar to your squiggly line drawing)
New wire connecting to starter relay (factory wire disconnected and tapped to new wire to keep it out of the way). I believe under the heat shrink is a fusable link.
Factory wire from alternator to starter relay disconnected (did not see signs of blisters on insulation)

​​
Another look at factory wire that would comnect to starter relay


So if I have this right, my GPCM and AIH are effectively disconnected.

Factory wire junction from starter rely going to AIH
Junction in factory wire for power to GPCM (Remember if you keep following factory wire it will lead to alternater, which is disconnected)
So I am looking to fix this in 2 stages

1) Quick fix as a trip to TN is planned for Monday (I have hard starts when temp get into the 50s)

2) Long term have a better solution like yours

So for the short term solution would it be possible to connect the factory wire at the glow plug relay (and not at alternator) to get power to GPCM / AIH?

I would think that would complete the circuit. Thoughts?

 

I haven't seen any mention of marine grade wire where each strand of copper wire is tinned.
It's a lot more corrosion resistant.
I use it for any engine bay rewiring and solder all lug connections.