Starter to Alternator Wiring Replacement

[Txcoop]

After installing a new civilian alternator the cables from the starter need to be replaced because they are too short. It appears to me that power wires going to the driver's side are spliced into these two cables. Can someone tell me if this is true and how do I lengthen the alternator cables if so?
Txcoop

 

[simp5782]

After installing a new civilian alternator the cables from the starter need to be replaced because they are too short. It appears to me that power wires going to the driver's side are spliced into these two cables. Can someone tell me if this is true and how do I lengthen the alternator cables if so?
Txcoop

What type of truck? M39,809 OR 939

 

[Txcoop]

What type of truck? M39,809 OR 939

Sorry, M923A2

 

[simp5782]

Sorry, M923A2

Tape the wires off in the main harness all of them going to the alternator. Use 4ga wire and eyelits. Run 4ga wire from alternator to starter post for ground and power. This allows a more direct power from the alternator to the batteries.

The original wiring goes back to the PCB on the drivers firewall Taping the wires off deletes the alternator power from going thru the pcb

This is the most simple fix for an A2 with the starter being so close compared to an A1 where the starter is on the opposite side of the motor.

 

[Txcoop]

Tape the wires off in the main harness all of them going to the alternator. Use 4ga wire and eyelits. Run 4ga wire from alternator to starter post for ground and power. This allows a more direct power from the alternator to the batteries.

The original wiring goes back to the PCB on the drivers firewall Taping the wires off deletes the alternator power from going thru the pcb

This is the most simple fix for an A2 with the starter being so close compared to an A1 where the starter is on the opposite side of the motor.

Thank you, but I was referring to a large bundle of wires splitting off under the truck going in front of the truck that I assume go to lighting, etc. I have already disabled the two wires you mentioned. I was surprised to find this bundle of wires tied into the alternator positive and negative cables directly beneath the alternator and fastened to the frame. It is all taped up and there is no access to the bolt that holds the wire clamp without removing heater hoses.
I thank you for the help this far.

 

[simp5782]

Thank you, but I was referring to a large bundle of wires splitting off under the truck going in front of the truck that I assume go to lighting, etc. I have already disabled the two wires you mentioned. I was surprised to find this bundle of wires tied into the alternator positive and negative cables directly beneath the alternator and fastened to the frame. It is all taped up and there is no access to the bolt that holds the wire clamp without removing heater hoses.
I thank you for the help this far.

Post a picture of what you have.

Headlight harness goes in on the drivers side just behind the radiator it cuts thru the frame

Generally there is a ground on the frame crosemember below the alternator. It's a stud type.

On the A2 the harness wraps the cross member going across supplies alternator then it keeps going to supply the starter. Unless someone has butchered your harness.

 

[Txcoop]

Post a picture of what you have.

Headlight harness goes in on the drivers side just behind the radiator it cuts thru the frame

Generally there is a ground on the frame crosemember below the alternator. It's a stud type.

On the A2 the harness wraps the cross member going across supplies alternator then it keeps going to supply the starter. Unless someone has butchered your harness.

Thank you. I will investigate further and try to get a decent picture .

 

[Txcoop]

I couldn't get a good picture, but I have attached one showing the wires coming from across the radiator shown taped. From you description the wiring harness should connect to the alternator and starter. If I had new alternator wires, two wires would be attached to to each terminal? One from the harness and one direct to starter?

 

[yotawheeler]

Tape the wires off in the main harness all of them going to the alternator. Use 4ga wire and eyelits. Run 4ga wire from alternator to starter post for ground and power. This allows a more direct power from the alternator to the batteries.

The original wiring goes back to the PCB on the drivers firewall Taping the wires off deletes the alternator power from going thru the pcb

This is the most simple fix for an A2 with the starter being so close compared to an A1 where the starter is on the opposite side of the motor.

So what is the benefit to bypassing the PCB? I understand if it’s the old generatior style unit but don’t the modern alternators have safeties in place?
I’m currently doing the swap and was just trying to figure out where to go with my hot lead. I was going to take it to the starter but the post looks too big for the 4 ga cable lug I have, so I was thinking I could just use the existing hot lead?

 

[simp5782]

So what is the benefit to bypassing the PCB? I understand if it’s the old generatior style unit but don’t the modern alternators have safeties in place?
I’m currently doing the swap and was just trying to figure out where to go with my hot lead. I was going to take it to the starter but the post looks too big for the 4 ga cable lug I have, so I was thinking I could just use the existing hot lead?

Alternators have voltage spikes that can occur this will blow the diodes in the PCB.

Starter lugs are available in 1/2" eyelit to go to 4 gauge. All my equalizer wires are 4ga

 

[Txcoop]

Thanks Simp5782. I just completed new alternator installation using the hot and ground off the harness. I think abandoning these two alternator leads and installing direct new ones as suggested.

 

[simp5782]

The ground goes to the frame stud just below the alternator on the front crossmember you can really use the ground on the harness and it's fine as long as the ground is good the hot wire I recommend a dedicated wire for charging purposes due to the voltage loss thru the harness to the pcb and then to the starter lug then to the batteries.

 

[yotawheeler]

Alternators have voltage spikes that can occur this will blow the diodes in the PCB.

Starter lugs are available in 1/2" eyelit to go to 4 gauge. All my equalizer wires are 4ga

good to know, thank you. managed to find some of the 1/2 lugs after reading your reply