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Thank you for the offer. I went ahead and ordered a new one.
Back up light wiring help
- Thread starter tlovvorn
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Hello, I am hoping to get some help here as I am stumped. PO has left behind a lot of wiring disconnected. I am currently on the reverse light. The red/purple wires come off the switch with male adapters (no power or grd). Nearby harness has 2 red/purple with female adapters (one 12v when ign on). Seems a perfect match based on how this should work. I tested the switch and rests at normally open and closes creating continuity. Thought all was good, made the connection and wires heat up when in gear. Disconnected, pulled out of reverse and checked the switch wires for ground, none...until I place in reverse again and then both are grounded. Is it possible for the switch to short to tranny (ground) only when in reverse? Bad switch?
pb4ugo
SILVER Star
It could be a bad switch. With the key on power is supplied to the switch, when you put it in reverse it completes the connection to the reverse lights. The switch doesn't have a ground to activate it, current passes thru it. It doesn't matter which wire you use to hook it up. The lights are grounded.
You said one of the female connectors coming from the wiring harness is 12v hot when the IGN is on. That wire comes from the IGN as I'm sure is obvious. The other wire with a female bullet connector runs back to the reverse lights and then grounds into the frame itself.
Now, it sounds like when in reverse gear your switch is closed and is passing current and heating the wires up? How hot? If the wires truly become hot or warm to the touch you have a short somewhere between the switch and ground.
Also, with the IGN on and one of the female bullet connectors at 12v, I'm not sure how you'd have ground at the switch wires. Without a spark display and or melting wires. 12v plugging directly into a grounded switch will melt your fuse almost instantly, so it's doubtful it's a grounded switch/switch wires.
The wiring sure seems straight forward i.e. single wire carrying current, load grounded. What you explain is exactly as I understand it to work but the grounding when in reverse is puzzling.
I was using some fairly cheap alligator extensions to test the circuit. These got very hot to where insulation was soft within 5-8 sec. To clarify, my test light is connected to ground and 12 volts. Green led indicates ground. When I place in reverse, I am getting ground at switch wires completing the circuit for the test light. I too would have thought instant blown fuse but no, just heated up wires. I quickly disconnected. Could be very weak ground? Enough for led to light but not enough for fuse to pop but then again, enough to heat up wires.
I think I'm getting the picture.
You've got alligator extensions run from the 12v female bullet connector coming out of the wiring harness to your test led light and then to one of the male reverse switch wires.
Question: is the other male reverse switch wire connected to anything when you do this test? Is it being grounded by lying against the tranny block or transfer case?
From what you describe you are completing the circuit and letting electrons flow to ground somehow.
Likely culprits are the switch itself, or if the 2nd male bullet connector reverse switch wire is connected to the 2nd female bullet connector wire that goes back and feeds the reverse lights, there is a ground or wire crossed somewhere further downstream. Aka between the switch and the tail lights.
Based on everything testing okay at start, I connected both wires from switch to wire harness with alligator clips. The clips are insulated so clear of grounding themselves. Once I noticed the heating up, I tested switch with only test light, no connections. Test light had pos and negative connected and this is where I seen ground when placed in gear. I am definitely leaning towards switch but found the possibility of it shorting itself when in gear very odd. I MAY consider removing the switch prior to purchasing one and try and confirm the short. Guessing... loose internal contacts falling against internal wall when in gear. I will follow up with my findings. Thanks for the feedback
pb4ugo
SILVER Star
Sounds like a bad switch. The switch should work installed or not. You could probably put it in reverse and check for resistance on each wire and the switch housing.
Does sound like a bad switch. Shouldn't be able to ground itself like that. Probably a loose internal that's hitting the sidewalk or similar like you are guessing. You should pull the switch and redo tests. Remove the possibility that the switch is grounding itself thru the tranny.
One further thought. When you had the switch connected to the wiring harness via your alligator clip setup. Were both the alligator clip wires getting hot? Or just the one connected to the 12 volt positive coming from the wiring harness?
if only the 12v positive wire was getting hot that would point even more at a bad switch.
One further thought. When you had the switch connected to the wiring harness via your alligator clip setup. Were both the alligator clip wires getting hot? Or just the one connected to the 12 volt positive coming from the wiring harness?
if only the 12v positive wire was getting hot that would point even more at a bad switch.
I note that the fuse has not blown during all of this even though something got warm. The reverse lights are 20W each, so 4A through a thin wire or bad connection could do that anyway.
Have you actually tried just connecting the switch without the test light.
Sounds like it might be a feature of the test light.
As suggested above, use a meter to test the resistance between the switch contacts and ground while it's not connected to anything.
Have you actually tried just connecting the switch without the test light.
Sounds like it might be a feature of the test light.
As suggested above, use a meter to test the resistance between the switch contacts and ground while it's not connected to anything.
South Texas 97
GOLD Star
"there is a ground or wire crossed somewhere further downstream. Aka between the switch and the tail lights."
The suggestions of checking each of the switch connections vs the body of the switch are both good. there should be no contact.
When in Reverse, or with the plunger depressed, there should be continuity between the two wires and still nothing to the body of the switch.
In my case, the wiring was fried back along the frame rail under the pax seat. There is also a ground there for the fuel level sender - worth cleaning up while you are under there...
The suggestions of checking each of the switch connections vs the body of the switch are both good. there should be no contact.
When in Reverse, or with the plunger depressed, there should be continuity between the two wires and still nothing to the body of the switch.
In my case, the wiring was fried back along the frame rail under the pax seat. There is also a ground there for the fuel level sender - worth cleaning up while you are under there...
It was only the hot lead warming up. Since both wires in gear show ground and switch does connect two side properly, the 12v feed is shorted and the pass through, also grounded, is feeding ground to back up light which, of course does nothing. Next is to find some time to remove seats and tran cover to access switch. More to come.
You can remove the switch from the underside without removing seats or tranny tunnel cover. 24mm socket. I did it just the other day and I snipped the two wires to allow the socket to fit on the switch and pulled it out. Easy.
Once it's out you can keep testing or/and replace. Installing a new switch or the old one with resoldered connections is a bit trickier, but doable. Instead of using a socket you can use a 24mm short wrench or an 15/26" short wrench.
Good to know. I didn't probe just looked from above with boot off. I will give that a shot. Would love for that to work!
Hey guys, I finally got around to this. After attempting to get to it from underneath with a socket or wrench and failing, I ordered a 24mm crow foot wrench. Worked perfectly! The switch worked while removed but was shorting out when installed. Ordered replacement and worked perfectly! Thanks for the input, hopefully this well help others with similar issues.
