truck not chargeing

joeydeherrera54 · 12-23-2007, 03:49 PM

i have an 83 gmc when i was leaveing work yesterday my battery was dead i jump it and it ran fine comeing home then this morning i tried to start it and was dead i found that it wasnt chargeing on the alternater only one wire has volts to it (the red one) the other wire i know should but it doesnt if i jump the to wires it charges fine what im wondering is where does the other wire go i know one goes to the starter but i dont know about the other one and is it ok just to jump the two wire or is it going to short something out

crabtruck · 12-23-2007, 07:08 PM

Of course once you have a dead battery you need to keep an eye on making sure the battery doesn't become it's own problem.
Jumping connections is shorting and can be as risky game.
This with volt gauge or idiot light ? That said, go to basics.
One red wire is to battery. Alt needs good ground via mounting, make sure it's clean and tight.
A red sensing wire comes off looking to see how much voltage is being output to truck.
A brown field wire goes to key either through a resistance if gauge or lamp if not.
You may want to do a quick check of fusible links and connections to the bvattery junction block.
What voltage is at battery when truck running ?
What is battery voltage if disconnected and let sit a few hours ?
If any of the three wires has no/low voltage at the alt, that where you go.

joeydeherrera54 · 12-23-2007, 07:12 PM

the battery is puting out 12.4 volts when it started for now but if i turn anything on its drops really fast so i know the alternater is not chargeing the battery if i jump the wires its goes to 14 or 15 vold and i tested it with a volt meter the red wire im getting 12 volts and the brown i dont have any so i know thats the wire i just dont know were it goes to

crabtruck · 12-23-2007, 07:19 PM

See above. Additionally, I think it goes through bulkhead connector #25 at third row third over, then to instrument cluster. Do check key connections as the problem may be there. Gauge or light ?

joeydeherrera54 · 12-23-2007, 07:21 PM

i have a gauge

crabtruck · 12-24-2007, 03:21 AM

Presuming your dash volt gauge is working, problem is post key / pre alt.
Key output spot for gauge and alt field connection should be same one.
One way:
Disconnect the battery and ohm the dead wire from alt back to connector on wall,
not likely the problem unless you have been working along it's route.
Add an extension wire to your ohm meter and you can find it again inside truck and follow to the key.
There is a 10 ohm resistance before you get to the key, forget whether a resistor or a resistive wire.
Another way:
With batt hooked up, key on, eng off - check that that wire coming from ignition key is hot.
If so, follow down to break in wire or bad resistor.
I can't remember if that truck had points, if it does don't leave the key in run too long.

12-23-2007, 03:49 PM	#1
joeydeherrera54 Senior Member Join Date: Jan 2007 Location: grand junction colorado Posts: 83	truck not chargeing i have an 83 gmc when i was leaveing work yesterday my battery was dead i jump it and it ran fine comeing home then this morning i tried to start it and was dead i found that it wasnt chargeing on the alternater only one wire has volts to it (the red one) the other wire i know should but it doesnt if i jump the to wires it charges fine what im wondering is where does the other wire go i know one goes to the starter but i dont know about the other one and is it ok just to jump the two wire or is it going to short something out

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12-23-2007, 07:08 PM	#2
crabtruck Senior Member Join Date: Jul 2007 Posts: 4,107	Of course once you have a dead battery you need to keep an eye on making sure the battery doesn't become it's own problem. Jumping connections is shorting and can be as risky game. This with volt gauge or idiot light ? That said, go to basics. One red wire is to battery. Alt needs good ground via mounting, make sure it's clean and tight. A red sensing wire comes off looking to see how much voltage is being output to truck. A brown field wire goes to key either through a resistance if gauge or lamp if not. You may want to do a quick check of fusible links and connections to the bvattery junction block. What voltage is at battery when truck running ? What is battery voltage if disconnected and let sit a few hours ? If any of the three wires has no/low voltage at the alt, that where you go.

12-23-2007, 07:12 PM	#3
joeydeherrera54 Senior Member Join Date: Jan 2007 Location: grand junction colorado Posts: 83	the battery is puting out 12.4 volts when it started for now but if i turn anything on its drops really fast so i know the alternater is not chargeing the battery if i jump the wires its goes to 14 or 15 vold and i tested it with a volt meter the red wire im getting 12 volts and the brown i dont have any so i know thats the wire i just dont know were it goes to

12-23-2007, 07:19 PM	#4
crabtruck Senior Member Join Date: Jul 2007 Posts: 4,107	See above. Additionally, I think it goes through bulkhead connector #25 at third row third over, then to instrument cluster. Do check key connections as the problem may be there. Gauge or light ?

12-23-2007, 07:21 PM	#5
joeydeherrera54 Senior Member Join Date: Jan 2007 Location: grand junction colorado Posts: 83	i have a gauge

12-24-2007, 03:21 AM	#6
crabtruck Senior Member Join Date: Jul 2007 Posts: 4,107	Presuming your dash volt gauge is working, problem is post key / pre alt. Key output spot for gauge and alt field connection should be same one. One way: Disconnect the battery and ohm the dead wire from alt back to connector on wall, not likely the problem unless you have been working along it's route. Add an extension wire to your ohm meter and you can find it again inside truck and follow to the key. There is a 10 ohm resistance before you get to the key, forget whether a resistor or a resistive wire. Another way: With batt hooked up, key on, eng off - check that that wire coming from ignition key is hot. If so, follow down to break in wire or bad resistor. I can't remember if that truck had points, if it does don't leave the key in run too long.