3g swap problem

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Jan 3, 2017 | 07:48 PM

*2fords*

Thread Starter

Fleet Mechanic

Joined: Feb 2009

Posts: 1,672

Likes: 20

From: Nixa

3g swap problem

This is on my 93 F-250
While my truck was in the shop today, i had them install my new 36 alternator and new battery cables.
When the guy installed the new charge wire and mega fuse, the truck wouldn't start.
The old charge wire has a yellow and a green wire spliced in at the relay end, and the guy didn't know what to do with them, as it wasn't pointed out anywhere on the site that I could find.
So I suggested leaving the wires in place on the charge wire and not connecting the other end to the alternator. So he connected the relay end with the 2 wires onto the mega fuse holder along with the new charge wire and it didn't start.
As of right now the new charge wire isn't installed, and the old wire is being used. I know it needs to be replaced with the new bigger charge wire so I need to know what is going on why won't it start with the new charge wire in place?

Oh and one other thing, may be related or not. My voltage gauge still drops when sitting at idle , like at a stop light. I thought this swap was supposed to end this problem? Any thoughts on this.
He put my smaller pulley on the alternator because with the stock size pulley on it, my belt is too short. Do I need to put the stock pulley back on and get a longer or stock belt? Does this have anything to do with the needle dropping.

Jan 3, 2017 | 09:55 PM

wtroger

Cargo Master

Joined: May 2001

Posts: 3,208

Likes: 13

The link below shows how a 3G should be wired. Coming from a 2g alternator the only wire I ever cut is the white with black striped one found in between the 2 larger wires found in the big plug. It is the stator wire and has to be connected as shown in the link. Run a new larger charge wire #2 or larger from the lug on alternator through your fuse and then to the hot side of the solenoid (relay). I just tape over the old plug and leave it. I don't touch anything in small three wire plug.

https://bzerob2.files.wordpress.com/...alt_wiring.gif

Jan 4, 2017 | 07:41 AM

PRIMERED79 SHORT BED

Laughing Gas

Joined: Jan 2012

Posts: 1,106

Likes: 25

I installed a 130amp alternator and just grabbed a alternator harness off a 94 f150.
All I did was change the plug on the green wire by the fender. It was different than my 92 so I crimped in the 94 plug.
I have 4g wire I believe running from the alt to a circuit breaker then to the solenoid.
But I also used the factory charge wire along with 4 gauge wire.
My gauge will move if I turn the headlights on or heater fan to full, but recovers quickly.

Jan 4, 2017 | 08:23 PM

*2fords*

Thread Starter

Fleet Mechanic

Joined: Feb 2009

Posts: 1,672

Likes: 20

From: Nixa

I'm going to have to dig into it more. but as of right now that diagram doesn't look too much like my wireing.
There's no starter relay in that diagram. I don't know if I even have the white with black wire
The green wire is plugged in where it was, the yellow wire i don't know where it goes. But the green wire and the yellow wire are both in the same loom as the original charge wire. The only thing he did different was leave the original charge wire off the alternator, but left it connected to the relay along with the new charge wire.
So basically everything is where it was originally with the exception of the bigger charge wire and mega fuse.
I thank you both for your imput. I'll try to dig into it this weekend sometime. Hopefully it'll be warm out.