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7030 wiring harness to alternator problem
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DIESEL View Drop Down
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Joined: 26 Aug 2013
Location: Sandhills
Points: 259 		Post Options Post Options   Thanks (0) Thanks(0)   Quote DIESEL Quote  Post ReplyReply Direct Link To This Post Topic: 7030 wiring harness to alternator problem
    Posted: 21 May 2023 at 2:10pm
I'm trying to figure out what's going on here, I put a new engine harness on a 7030 with a new 3 wire delco alternator. I plugged it into the alternator and turned the key on for the fuel pump to prime the system after installing new injectors, and the resistor started to melt the harness. If tractor is running and I plug it into the alternator everything works as it should, putting out 14 volts and resistor isn't hot, kill the engine with key on and it smokes again. Any help would be greatly appreciated, I hate wiring problems.
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steve(ill) View Drop Down
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Joined: 11 Sep 2009
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Points: 81133 		Post Options Post Options   Thanks (0) Thanks(0)   Quote steve(ill) Quote  Post ReplyReply Direct Link To This Post Posted: 21 May 2023 at 4:21pm
I dont claim to know what all the wires are doing, but the grey wire with the resistor is going to #1 spade terminal.. It is getting voltage FROM the ignition switch THRU the resistor to the alternator when the key is on... When the motor starts, the alternator puts out voltage BACK thru the wire to the resistor, which basically cancels out the voltage coming from the switch and the resistor has NO voltage drop ( or very little) , thats why it does not get hot when running.

Big question is WHY does the resistor get hot with 12v from the key ??   Only thing i can think of is bad resistor or wrong resistor .... the resistor i use for the alternators is a ( 10) 100 ohm 10 WATT and is 10 times that big ............ I dont know if this is standard for "THAT HARNESS", but the resistor seems very small to me... i would ask the vendor..

( new link to 10 ohm resistor, not 100 ohm)..



Edited by steve(ill) - 21 May 2023 at 5:33pm
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steve(ill) View Drop Down
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Points: 81133 		Post Options Post Options   Thanks (0) Thanks(0)   Quote steve(ill) Quote  Post ReplyReply Direct Link To This Post Posted: 21 May 2023 at 4:27pm
You could cut the solder joint at the resistor on one side... See that you have 12 v to the resistor from the switch when ON... Then have 14 v from the alternator on the other side when running...... maybe just a new resistor ?
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Points: 259 		Post Options Post Options   Thanks (0) Thanks(0)   Quote DIESEL Quote  Post ReplyReply Direct Link To This Post Posted: 21 May 2023 at 4:57pm
Thanks Steve I'll try that, it's an AgCo wiring harness I was wondering about a bad resistor but I'm definitely not an expert when it comes to wiring.
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Points: 81133 		Post Options Post Options   Thanks (0) Thanks(0)   Quote steve(ill) Quote  Post ReplyReply Direct Link To This Post Posted: 21 May 2023 at 5:24pm
maybe i dont get it... BUT, normally there is a resistor or diode or idiot light ( on the dash) that is in the #1 terminal wire and originates from the ignition switch.. I know of no other reason for a resistor in the line.

If that is a Delco 10SI or similar it works like this... I SHOULD have said 10 ohm, 10 watt... i use the 100 ohm 10 watt on the CS130 smaller unit.






Edited by steve(ill) - 21 May 2023 at 5:28pm
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Joined: 26 Aug 2013
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Points: 259 		Post Options Post Options   Thanks (0) Thanks(0)   Quote DIESEL Quote  Post ReplyReply Direct Link To This Post Posted: 21 May 2023 at 8:37pm
I'll see if I can find a bigger resistor tomorrow and go from there.
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