HELP 86 s10 with charging issues.

[stompn5pt0s]

Im hoping someone can help me, I have a bud that owns a 86 s10 jimmy 4x4with a 305. He bought it like this for 500.00 and tagged it historic just to have a daily commute to work. Im a chevelle guy and have helped him with a few things on this truck but he has a problem that has me stumped. Heres the deal, When hes driving down the highway the volt meter guage drops to 8 and he losses all the lights in the truck, even the power windows wont work. the head lights die out and eventually quits until he can get a jump from someone. Well I tried a few things to see if the alt was bad, when I pulled the hot cable off the battery while she was running she kept running and the volt meter goes up to 18. when you put the pos. cable back on it drops to 8 again. also he told me his tach was bouncing all over the place. and his battery terminals are real hot, I mean scorching. I thought maybe he had the wires crossed on the starter and tried a few different things with no change. theres the main cable that goes from the battery to the starter also theres two blue wires that were spliced together on the main post. then theres a red wire on the small post closest to the block. the alt has a post and a plug the wire on the post runs to battery, and the plug is tied into the harness. looks like a 4 pin plug. if anyone could point me in the right direction or maybe has a diagram that I could go by to do it right, I would and he would appreciate it. sorry so long just trying to give you the info i know just trying to help a bud out. By the way nice site Im thinking about a s10 short bed in the future.... Possible Member. Thanks in advance on any ideas or info..

[ZR1BLAZER]

re run the wiring. ground the battery to the motor and the frame. run the positive from the battery to the starter and from the battery to the bulkhead fitting. then run the alt to the bulkhead or straight to the battery. sound like there is a gound in the power system causing a short when the battery is connected.

[dieselman010]

Im hoping someone can help me, I have a bud that owns a 86 s10 jimmy 4x4with a 305. He bought it like this for 500.00 and tagged it historic just to have a daily commute to work. Im a chevelle guy and have helped him with a few things on this truck but he has a problem that has me stumped. Heres the deal, When hes driving down the highway the volt meter guage drops to 8 and he losses all the lights in the truck, even the power windows wont work. the head lights die out and eventually quits until he can get a jump from someone. Well I tried a few things to see if the alt was bad, when I pulled the hot cable off the battery while she was running she kept running and the volt meter goes up to 18. when you put the pos. cable back on it drops to 8 again. also he told me his tach was bouncing all over the place. and his battery terminals are real hot, I mean scorching. I thought maybe he had the wires crossed on the starter and tried a few different things with no change. theres the main cable that goes from the battery to the starter also theres two blue wires that were spliced together on the main post. then theres a red wire on the small post closest to the block. the alt has a post and a plug the wire on the post runs to battery, and the plug is tied into the harness. looks like a 4 pin plug. if anyone could point me in the right direction or maybe has a diagram that I could go by to do it right, I would and he would appreciate it. sorry so long just trying to give you the info i know just trying to help a bud out. By the way nice site Im thinking about a s10 short bed in the future.... Possible Member. Thanks in advance on any ideas or info..make sure your bud has a good ground from
the engine to the body of the vehicle.