my 85PU no backup lights
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my 85PU no backup lights
i have a 85PU but my backup lights dont work. brake, blinker and running lights are fine. i am wondering where the short probably is, i found that the red wire is my reverse light but i dont see open wire when i trace is. since its both lights i figure its a short in the main line before it splits. can anyone give me some suggestions to finding it, or maybe where it starts to see if it pulled out or anything. also any fuse relating to lights is fine.
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sweet man thanks. i woulda never looked there, if its bad how can i replace it? is it an easy fix or something to just take into a shop and let them do? also how do i disable that dang buzzer, people talk about doing it but i dunno what they did... disable the actualy pressure switch or just find the buzzer and cut the wires?
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that makes complete sense.. i appriciate it.. nice thing is since iv done a good job rebuilding this truck and putting money into it my parents are going to let me bring my second truck home to start rebuilding in my back yard
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so i pulled the switch apart, the wires are fine on both sides so there is no short there, i used a voltage tester on the switch coming out of the transmition.. i had nothing, so does that mean that its bad and i need a new one? or would there be no voltage coming from it anyway? i did it in and out of reverse and still had nothing..
#7
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A voltage tester will show you nothing at the switch. Why? It is just a contact that opens and closes. You would want to use an ohm meter (resistance) or battery powered test light to see if there is continuity inside the switch contacts while in reverse (and no continuity when in any other gear).
http://www.4crawler.com/4x4/CheapTri...oUseAnOhmMeter
http://www.4crawler.com/4x4/CheapTri...oUseAnOhmMeter
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#9
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Switch sends power to the backup lights. The switch may give you a reading on a meter (micro-amps of current) but it may not flow enough current to light the light bulbs (several amps of current). Or the 12 volt source at the plug may be bad. So check the connector for 12 volts (one pin should be hot). Then try a jumper wire in the lug to tie the two pins together like the switch would do. If none of that works, check voltage and ground connections at the bulb sockets. If still problems, trace the wiring looking for an open or short circuit.
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im going to replace the switch just because its old and then ill see if they work after that, if not then ill look at the plug. if the swtch is bad then i wouldnt get the 12 volts at the bulb connector anyways right? so i kinda have to make sure the switch is working 100% before i can narrow down other possibilities..
#11
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Easy check of the switch is to plug in a jumper wire into the plug connecting the two pins the contact together. How to make a jumper wire? Take a paper clip or piece of wire and bend into a "U" shape and shove it into the plug making contact with both pins, something like this:
If backup lights light, switch is bad. If not, something else is the problem.
If backup lights light, switch is bad. If not, something else is the problem.
#13
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You have the switch screwed into the transmission. Then you have the connector that plugs into the switch and is what has wires connected to it. Unplug the connector and shove a jumper wire into the connector that you just unplugged. What you want to do is connect the one pin in that connector that has 12 volts on it to the other pin that that sends power to the backup lights.
#15
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Well in that case, you take the "divide and conquer" approach. You are currently about in the middle of that circuit. You need to find out if you have a solid 12 volts at that plug. If so, then the problem lies between that plug and the backup lights. If you do not have 12 volts at that plug, then the problem lies between the plug and the battery:
- http://www.4crawler.com/4x4/CheapTri...leshootingTips
- http://www.4crawler.com/4x4/CheapTri...leshootingTips
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i can just use my normal voltage tester on the plug side like i did on the ohm tester on the switch side? do i need to have it in reverse to test and see if it has 12 volts?
Last edited by nomiss05; 08-04-2008 at 01:02 PM.
#17
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To measure voltage you use a volt meter voltage tester). To test resistance you use an ohm meter. So to test voltage, set meter to volts and check the pins. Note there is no ground in that connector, so put the black probe on some bare steel of the frame and the red probe on the connector pin. One should be hot (i.e. reads 12 volts with the ignition on) and one is not hot (i.e. has no voltage).
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okay so where does the wire start to trace it from the start to the plug? i figure ill just keep testing it every so often to see if i have 12 v still and ill narrow down my short location
#20
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A Factory Service Manual will have the wiring diagram in it with wire colors, etc. There are PDF versions on-line that you can down load. That power comes from the ENGINE fuse circuit, then runs to the switch and back to the lights. You can follow the wires from the transmission up to the main wiring harness up in the engine.
And unless you have blown fuses, you are probably not looking for a short circuit. Rather it would be an open circuit (i.e. a broken wire or bad connection some place) that is preventing current from flowing.
And unless you have blown fuses, you are probably not looking for a short circuit. Rather it would be an open circuit (i.e. a broken wire or bad connection some place) that is preventing current from flowing.