'85 Dodge Ram truck Reverse lights

CraigE

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I have a 85 Pick Up with inoperable reverse lights. I believe the switch is in the Neutral Safety Switch. I changed this since it was only $10 but I still have no lights. Using my Ohmmeter I was not able to conclude how the switch was working? I know one lead on the three lead Switch plug has 12 V with the key on. Anyone familiar with the schematic? Does the switch ground a lead or send 12V out another wire? Thanks CRAIG
 

JackC

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Without looking it up, I assume at only $10 it is the old fashioned switch under the dash on the str col instead of the new ones on the trans, under the hood??

Regardless of which it is, they are both adjustable, with slots so they can be moved one way or the other to get the back up lights to be operable. That may be your problem??
 

The old man

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The way I see the back up switch that is on the transmission, is that 12 volts is coming in at the Red/Blk wire and when switched to reverse, 12 volts from that wire is sent down the Blk wire to one side of the backup bulb, and the other side of the bulb is grounded by the white wire. If these are the colors of your wires, this is what I got on it.
 

LynnM

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The switch in the trans has three terminals Center ground other side one is for neutral other is for back up lights... The switch is grounded depending on position I don't remember it having 12 on it....
 

bp042665

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the old man is right on the wires as i looked it up too what the switch does is it has 3 pins on the out side and 1 on the button side which is touching on the rooster comb on the in side ot tranny so when it goes to reverse it pushes the contacked in side to give power to lights and will ground in gear so you cant start it
 

Mobile Dan

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My definition of how that switch works...

Center terminal grounded in Park or Neutral. This enables starter relay.
Outer two terminals become connected when in Reverse. This connects battery power to reverse lamps.
 

The old man

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Danica: You say more in two senetnces that I can say in a whole paragraph. Spot on ole chap!! LOL
 

CraigE

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It is a transmission switch, and when I bought the new one I checked for continuity on the pins and did not have any. I guess that is why the lights still do not work. I will try another new switch. Anyone else tired of buying junk? I knew I had 12 volts on the one outside wire, just was not sure of the switch operation since I did not see a continuity change with my meter when I pressed the plunger. Thanks for the input CRAIG
 

The old man

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Before you condemn the switch, my diagram shows 12 volts (red/blk) coming into the center connection and that there should be continuity between the center and outer connection when the reverse buttom is pushed. The other end connection has ground connection coming to it. This is an old schematic (1985), but that is absolutely the way this switch is. The Dark green/white wire on this schematic is the ground wire coming to the switch connection on the other end. To test the circuit just connect the red/blk wire to the black wire and see if the backup light comes on when the ignition is on. They should. If not you may have a ground issure on the bulb (white wire), broken wires etc.
 

The old man

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Just be careful and don't connect the 12v wire to the Darkgreen/white wire, which is the ground wire to the stater solonoid when in park, or you will blow a fuse. The ground goes away when you are in reverse or drive and the starter solonoid with not energize. You still have 12v to the switch with the key on don't you? If not you may have blown a fuse.
 

Mobile Dan

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I think I see a discrepancy between the old man and I about which pin does what. I would recommend you listen to him; seems that he has done more research. On the other hand, if you install a jumper into the connector between socket "A" and "C", and the reverse lights come on when you turn on the key,(not Crank) that would leave the center post "B" as the starter relay ground source.
 

The old man

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Danica: That is why I included the colors of the wire. The diagram I have shows different than yours but maybe my diagram is wrong. I just relay what I see in my diagram. Not trying to confuse the situation or second guess anybody.. Just trying to help out. I suggest that Craig try both ways to try and find out which pins are which so as not to condemn the switch if it is in fact good. The switch may change from year to year for all I know.
 

Mobile Dan

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A link to schematic, may be from a newer Dodge.

http://ww2.justanswer.com/uploads/amedee/2010-06-29_175431_1.gif

There are two switches shown here...one for automatic, one for manual.
 

The old man

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I look up other years just for my curiousity to see if any of the years were different in the eighties. I went from 1984 to 1989. 1984 and 1985 were basically the same with the wire colors I noted . But from 1986 to 1989 the wire colors changed from year to year. The 12v hot wire was even white in those years after 1986. 1990 look like a new ball game.

When I changed out a deck lid on my 2003 chrysler town and country from a 2000 salvage deck, I could not even use my old wiring harness from the 2000. I had to use the one from the 2003 because the automatic lock worked backwards. Go figure.
 
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