12v wiring question. Low amps or volts? - JeepForum.com
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post #1 of 6 Old 12-17-2019, 06:00 AM Thread Starter
mc190
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12v wiring question. Low amps or volts?

Trying to clean up the wiring in the engine bay, so locating some key-on 12v sources. I found 2 but for some reason when I hook them up, they will not power up the 12v item (stereo, back up lights).

for example: when I run a wire directly to the battery from the reverse light switch, it works fine- they turn on when you put the Jeep in reverse. When I connect it to a 12v source from wiring out of the fuse box-no go. this particular wire is red goes to the BU/seat belt fuse

Same with the stereo, when I hook it up directly to the 12v battery, everything is fine, but when I put it to the 12v source out of the underdash fuse box, nothing.

Have another key-on power source that was not being used. This is a brown wire that goes into the dome light fuse. Same thing. It reads 12v with my multimeter, but when I try to use it to power up either the stereo or reverse lights- nothing.

Everything else is working. all turn signals, hazards lights, high beams.
The horn is not, it's got to be replaced and re-wired.

photos of the fuse box (with the fuses removed from the bu/seat belt and dome-courtesy slots).

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Fuse.1.jpg   fuse2.jpg  
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post #2 of 6 Old 12-17-2019, 07:38 AM
Fourtrail
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Sounds like corroded connections at the fuse. just like on the ground side, you can have a corroded connection on the positive side that will show voltage when you use a meter, but when you put a load on the circuit, you have too much corrosion to pass enough amperage for the circuit to work. I would visit your FLAPS and pick up a can of electrical contact cleaner. Be sure to work the fuse in and out a few times after you spray the slot in the fuse box so you get the cleaner down into the contacts. Let the cleaner fully dry before testing the circuit as you may get a good connection when wet, but lose it when it dries.

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post #3 of 6 Old 12-17-2019, 08:22 AM
John Strenk
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That one fuse terminal does look rather green....

corroded-fuse-socket.jpg

Clean it up real good

Like fourtrail says, a meter probe is a point and can break through the corrosion to read the voltage but a spade terminal is wide and flat and the corrosion can keep it from making good contact.

Are you trying to "T" into a fuse socket? There are some constant 12 volt tap on the fuse box you can just plug into..


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post #4 of 6 Old 12-17-2019, 01:23 PM Thread Starter
mc190
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I thought that might be the case- crappy fuses. I pulled them last night to see if they were questionable. They were not blown, but definitely not clean. I did not have any to swap out, so just buttoned her up for the night and wanted to get some forum help on this issue. I'll grab some new fuses on the way home, spray the box down with some cleaner and see what that does.

Like most electrical problems- the simplest solution works most of the time.

Hoping to get some of these final issues done by x-mas, then spend a week doing body work and then PAINT.

Still have to get my fuel gauge working, the left turn signal to light up on the dash (it works, just does not light up on the dash) and the 4x4 indicator light working. But I think those are issues with the ground at the speedometer gauge.

Jeeps running great. It's got a lot of get up and go. Much more than what I previously remember from a 6-cylinder YJ from years ago.
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post #5 of 6 Old 12-18-2019, 02:05 PM Thread Starter
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Quote:
Originally Posted by Fourtrail View Post
Sounds like corroded connections at the fuse. just like on the ground side, you can have a corroded connection on the positive side that will show voltage when you use a meter, but when you put a load on the circuit, you have too much corrosion to pass enough amperage for the circuit to work. I would visit your FLAPS and pick up a can of electrical contact cleaner. Be sure to work the fuse in and out a few times after you spray the slot in the fuse box so you get the cleaner down into the contacts. Let the cleaner fully dry before testing the circuit as you may get a good connection when wet, but lose it when it dries.
we'll that seemed to work. Sprayed some cleaner and new fuse and got reverse lights at that fuse. Spent some time and got the 4WD indicator light working.

I think I'm going to just change out the speedometer assembly as it's looking pretty bad-rusted bezel. Maybe I'll get lucky and it will fix the few other things- Fuel gauge, right indicator light and brake light and then I might actually have a jeep ready for the road.

I'll probably need a new parking brake assembly, after cleaning it up, still does not ratchet correctly.
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post #6 of 6 Old 12-18-2019, 02:20 PM
walkerhoundvm
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Plenty of good writeups online for diagnosing fuel gauge issues. Rule out the sending unit first using available resistance info; if resistance findings are normal, switch focus to the gauge(s) and their wiring. Resistance info is also readily available for fuel/temp gauges themselves, which sorta work in concert with one another.
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