60 Amp Alternator wiring

[Bowtie70SS]

I have been trying to figure out my alternator issue as well as learning/absorbing as much as I can about the M35A2. I have seen a few pictures where it appears that the 60 amp alternators have 3 small wires, 1 cable to battery,and 1 cable to ground. My setup has the 2 cables but only 1 small wire. Also my alternator is basically new. I took the regulator off and inside is spotless and the outside looks great too. It is the Hellas style alternator which is one of several different suppliers. If someone could shed some light on this I would sincerely appreciate it.

 

[Bowtie70SS]

I am wondering if someone just slapped a late model alternator on there and hoped it would work.

 

[clinto]

I am too tired to go outside and look at mine but I can direct you to a super nifty schematic:

http://www.steelsoldiers.com/showthread.php?3843-Peter-Bog-s-CAD-deuce-schematic!

Define "late model"-because what's pictured is the correct military 60A unit. Your truck might have originally had the 25A generator. If so, there will be two cannon connectors above the steering column, screwed together.

 

[Bowtie70SS]

My truck is a 1970. The pic I above is from one rebuilt in 2001. My alternator only has 1 power cable, 1 ground cable, and 1 small 14 gauge wire thats it.

 

[Bowtie70SS]

I see in the schematic there are only 3 wires. I wonder what the extras in the pic above are? Accessories? I think that Hella alternator is the bastard of them all as I havent found the TM that covers it yet. I am taking it to have it tested tomorrow and that will tell. I have 2 brand new batteries so I need to have a good alternator too.

 

[Diecorpse]

I would say the others are from the generator if it had one, otherwise I would assume to power accessories. That also looks like an alt from an A3, I don't know poo about those, an A2 would usually just have the three wires. Thats my guess. What kind of issues are you having? What kind of batteries do you have and how new/old are they?

 

[swbradley1]

What is the problem you are trying to fix?

 

[Bowtie70SS]

No Charge. I fixed the typical broken wire down by the starter. I have brand new batteries now, the old ones were 7 months old and i got them warranteed. The alternator looks brand new.

 

[swbradley1]

So you have fully charged batteries (charged with a charger, not truck)?
You have approximately 25VDC on the batteries AND at the alternator red lead?
You are saying with the truck running you do not have approximately 28VDC at the batteries AND the alternator red lead, correct?

Have you pulled the cover off in the pic to see if the field exciter wire is connected?

When you have it tested the guy needs to know that he has to put a voltage on the exciter terminal in order to get it start, my guy did not. Both of Gimpy's that I took in tested bad until I told him that it was not self excited. With applying a voltage to the exciter they both worked and put out 58Amps each.

 

[OldSchoolAmerica]

As mentioned earlier, that picture above is from an A3 with the CAT 3116. Here's a snapshot of the alternator schematics from TM 9-2320-386-24-1-2. I believe the two wires in question are 770N and 770P.

 

[Recovry4x4]

Before you send off to have the alternator checked, see if there is battery voltage at the 14GA exciter wire with the power switch on. If there is, have it checked, if not, that would likely be your problem.

 

[Bowtie70SS]

I knoiw what the picture is from, maybe my question is not well written. Is the Hellas alternator which I have or do any of the 60 amp alternators require different wiring like the A3? I want to make sure what I have is wired correctly. I realize the extra wires on the A3 could go to the tach or some other accessory.

 

[Recovry4x4]

All of the 60A alts are wired the same. With that said, I've not actually held the Hella in my hand.

 

[Bowtie70SS]

I fixed the 14 gauge wire down by the starter, it was broken. I still had no charge after that. I do not have the TM that covers the hellas alt.

 

[Diecorpse]

I would think even if you had a broken wire, the alt should still charge the batteries as long as the ground and the lead from the alternator are intact. Have you checked your battery connections and made sure the wire under the insulation are not corroded? Also check your ground wire as well. A lot of silly problems can result in poor connections. Once all the connections problems are ruled out, would I then take off the alt to have it checked out. Also as mentioned before, make sure the batteries are fully charged, or have them checked if you are not sure, usually free at most auto outlets. As far as correct wiring, the lead and ground are the main wires to and from the alt. The 14 gauge wire can be disconnected and still charge, or at least mine did. If the alt actually checks out being bad, I would look into aftermarket alternators. They can be cheaper and ordered by most auto outlets. Hopefully any info I provided assists you. . .

 

[Bowtie70SS]

Thanks!! I just had altnator tested. Voltage was a little low then we turned it up to 27.5. Tested good under load. Now that I know that I will put it all together withe the new batteries and see what happens.

 

[m-35tom]

the alt is very simple, most people want to complicate it because i guess they don't know how it works. there is the large wire that has voltage on it all the time. make sure it is the same voltage you read at the batteries. this will confirm there is no bad connection causing voltage drop. there is a ground wire sometimes, mine has none and works because it is all bolted to the engine that is grounded. last there is the 14 ga wire that is not really 'the exciter' wire, but it tells the regulator that the switch is on and it is ok to start charging. you have to have power on this wire when the engine is running or it will not charge. do not trust the volt meter on the dash, check things with a known accurate tester. it is that simple.

 

[Bowtie70SS]

The first thing I did was to check voltages with a multimeter at the batteries, power wire on alternator, and exciter wire. I found that wire broken 14 gauge wire down by the starter and I repaired it first.It still did not charge per my multimeter. I took the batteries and got them replaced under warranty and while I was at it I had the alternator tested and we adjusted it. I drove the truck tonight and the alternator charged great and it was charging the whole time even with all the lights and everything.

 

[Ryan123]

This might be posted somewhere but what alternator is it that replaces the generator?

 

[Bowtie70SS]

From what I have seen there are a couple of alternators Leece-Neville (Prestolite) and Hellas off the top of my head. The NSN is the same for them but they are made by different companies and appear nearly identical. Unfortunately their parts do not interchange. I think that was short sighted.