Wiring issues

[Ricko1966]

Okay I've got 12% charge so this is the brief version.If you put your meter in volts scale and touch it to battery-post the other meter lead to the body. Nothing on, it should read zero on the meter. Turn some things on,there's going to be some loss,1/2 volt reading on the meter that means the cable and all it's connections can carry 11.5 volts. When you turn things on and meter reads 4 volts that's bad it means that wire and it's connections can only carry 8 volts. So back to read the loss between the battery negative and the body with lights on let's see what kind of loss we have on the negative side. Same thing battery + to headlight switch plus. Let's see if both those circuits are capable of carrying sufficient voltage. Another simple to understand as an example If I have a slow starter,and I put one lead of a meter on the + battery POST not terminal the other lead onnthe starter POST. Now if engage the starter and my meter reads 3 volts,that means I have a bad connection or a cable deteriorated or broken in the jacket but that cable and it's connections can only provide 9 volts. What ever the meter reads subtract that from battery voltage that will tell you how much current that wire and its connections can carry.

 

[Ricko1966]

I keep charging the phone a little then come back to check on things and end up rewriting 1/2 of what I ve already said,Sorry. But woo woo I've got 18% charge I'm good for a little bit.

 

[86k5blzr]

Yes but if he's got an insufficient connection that won't pull 12v through it he could drop 6 volts,he could drop 11 volts. But it can be measured and isolated with the meter. I'm at 6% charge I'm done for a while, maybe the night. But search our search engine I'm sure I put up a post on how to do volt drops to find bad connections,broken wires. Another quick example cause it's so basic and easy to understand,if I had a slow cranking starter,I could put 1 lead on the positive battery POST,not terminal, and 1 lead on the starter POST then if you engage the starter and the meter reads 4 volts the cable and all the connections can only carry 8.Now you need to clean all the connections maybe it's just a bad connection. Still got 4 ? Okay the crimped ends are corroded inside or the wire inside the jacket has broken several strands. Buy by providing a parallel path we can read on the meter how many volts we are dropping through the cables and connections. I believe it's supposed to be .1 volts loss per connection as spec, as long as I'm not seeing over .5 .75 volt I'm not going to get excited,but we might see 6 on one of his wires,that would be awesome. I still want to know if the correct bulbs are in it though. front and rear because a single element in a dual element socket,even in the front can create a backfeed.

I really appreciate you suggestion on the wrong bulbs it had sylvania zevo bulbs in it and when I pulled them It popped right up.Thank you Rick!

 

[86k5blzr]

Okay I've got 12% charge so this is the brief version.If you put your meter in volts scale and touch it to battery-post the other meter lead to the body. Nothing on, it should read zero on the meter. Turn some things on,there's going to be some loss,1/2 volt reading on the meter that means the cable and all it's connections can carry 11.5 volts. When you turn things on and meter reads 4 volts that's bad it means that wire and it's connections can only carry 8 volts. So back to read the loss between the battery negative and the body with lights on let's see what kind of loss we have on the negative side. Same thing battery + to headlight switch plus. Let's see if both those circuits are capable of carrying sufficient voltage. Another simple to understand as an example If I have a slow starter,and I put one lead of a meter on the + battery POST not terminal the other lead onnthe starter POST. Now if engage the starter and my meter reads 3 volts,that means I have a bad connection or a cable deteriorated or broken in the jacket but that cable and it's connections can only provide 9 volts. What ever the meter reads subtract that from battery voltage that will tell you how much current that wire and its connections can carry.

Awesome information I'm gonna save this for future reference

 

[86k5blzr]

My thought was that if the battery was serviceable the voltage drop shouldn't go below 10.5 or thereabouts. 6 v is so far in the mud that it is either has a bad cell or is overall pile of scrap.

I could be wrong

Voltage drop wasn't too bad I believe the led bulbs were backfeeding. Appreciate the suggestion though for sure

 

[Durwoods85]

I had similar issues helping a friend with his tractor and his son with a boat. On the tractor, had 12v everywhere but when you turned the key to start it the lights would dim and the starter would engage the flywheel but not spin it. Found bad positive battery cable, looked fine and all connections were clean but was corroded somewhere in the cable and could not carry the load. New cable and all's well. Same situation on his son's boat but it was the ground cable. Again, all connections were clean and good but cable was bad. The way we figured it out was we put a jumper cable from the positive cable on the battery to the starter effectively bypassing the existing positive cable, started right up. Similar test on the boat with the ground cable.

 

[86k5blzr]

I had similar issues helping a friend with his tractor and his son with a boat. On the tractor, had 12v everywhere but when you turned the key to start it the lights would dim and the starter would engage the flywheel but not spin it. Found bad positive battery cable, looked fine and all connections were clean but was corroded somewhere in the cable and could not carry the load. New cable and all's well. Same situation on his son's boat but it was the ground cable. Again, all connections were clean and good but cable was bad. The way we figured it out was we put a jumper cable from the positive cable on the battery to the starter effectively bypassing the existing positive cable, started right up. Similar test on the boat with the ground cable.

I had thought the bulbs had fixed it lol but I believe I had the same situation as you

 

[86k5blzr]

Update: when I pulled the bulbs the voltage went up to 12v but when it had a load it if fell back down so I kept checking things and found the wires to the starter were terrible so I replaced those wires and everything is working great thanks to everyone for the suggestions!

 

[Ricko1966]

Update: when I pulled the bulbs the voltage went up to 12v but when it had a load it if fell back down so I kept checking things and found the wires to the starter were terrible so I replaced those wires and everything is working great thanks to everyone for the suggestions!

Glad you found it. That's what I was talking about with volt drop. Wires that can't support the current draw. Don't know how to do emoji so thumbs up.

 

[86k5blzr]

Glad you found it. That's what I was talking about with volt drop. Wires that can't support the current draw. Don't know how to do emoji so thumbs up.

Yessir I had remembered you said that so I checked those wires out and it's a miracle anything worked lol thanks Rick for your suggestions!

 

[Ricko1966]

Yessir I had remembered you said that so I checked those wires out and it's a miracle anything worked lol thanks Rick for your suggestions!

I hope others read this and learn from it. Have a great day.

 

[86k5blzr]

I hope others read this and learn from it. Have

I hope others read this and learn from it. Have a great day.

Me too, you as well

 

[edgephoto]

The reason you measure 12 volts when the circuit is not trying to operate is you are measuring potential across an open circuit.

When you measure 6 volts when the circuit is energized means you have a 6 volt drop someplace. Something else is "stealing" your 6 volts. An added resistance. A few voltage drop measurements on the circuit and you can have it diagnosed quickly.

When you have a lot of strange stuff going on it is most likely a bad ground. This assumes, as Rick said, you have the correct light bulbs installed. I have seen many times where single filament bulbs are installed in dual filament sockets, or vice-versa.

I bought a car one time a couple states away. I watched it not sell several times on eBay because "it cranks and won't start, we tried everything" and "the lights are completely messed up and probably needs a new wiring harness." I got there paid them the $200 I agreed to pay While the guys who were selling it went in the house I got it running and had found the ground was not connected for the rear lights and they had the wrong bulbs installed. There were tons of loose bulbs in the trunk. I got the lights working, slapped a borrowed dealer plate on it and drive it 2 hours home. I drove that car for 3 years. My point is, don't get frustrated, start with the basics and check everything carefully and systematically.

I did not invent this phrase but I use it all the time when helping to get technicians back on track with diagnosis, "Plan your work, work your plan". Write down possibilities, make a plan to rule out these ideas and stay focused. If you find something along the way make a note of it but don't lose focus.