Fixing and finding backup light wires 78k10

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squaredeal91

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Hey all, im getting ready to fix the backup (reverse) lights on my daily 78K10. I have to leave for work when its dark and cant see to turn around safely. I ordered the correct reverse switch for my transmission but have no idea what color wires to look for and Its never had backup lights since ive had it . Originally had a th350 transmission but now has the sm465. I have a pigtail with the correct plug hanging in the area but im pretty sure its for the 4x4 light on my dash and I really want to fix that too because I miss seeing that come on when putting it in 4 wheel because it looks cool lol.
Ive looked at diagrams but im still not sure what color it should be at the back of the truck.
My first main question is what color wires should I look for.
 

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Ricko1966

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Hey all, im getting ready to fix the backup (reverse) lights on my daily 78K10. I have to leave for work when its dark and cant see to turn around safely. I ordered the correct reverse switch for my transmission but have no idea what color wires to look for and Its never had backup lights since ive had it . Originally had a th350 transmission but now has the sm465. I have a pigtail with the correct plug hanging in the area but im pretty sure its for the 4x4 light on my dash and I really want to fix that too because I miss seeing that come on when putting it in 4 wheel because it looks cool lol.
Ive looked at diagrams but im still not sure what color it should be at the back of the truck.
My first main question is what color wires should I look for.
When you go to backup put your automatic shift column in reverse and see if your back up lights come on. The backup light switch on an automatic was at the base of the column. If they didnt change columns the wires should be down there. Look for light green and pink. The pink is probably already in use for the starter.
 
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squaredeal91

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When you go to backup put your automatic shift column in reverse and see if your back up lights come on. The backup light switch on an automatic was at the base of the column. If they changed columns the wires should be down there. Look for light green and pink. The pink is probably already in use for the starter.
Thank you, I didn't even think about the column. My starter wire is purple. I forgot to add that my truck was originally a step side but came with a flatbed on it and I have wired in peterbuilt trailer style taillights. So im looking for a light green wire at the back of my truck? Ill start by putting the column in reverse and testing for power at the back.
 

CalSgt

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IIRC anything pink under the dash should be hot (+12v) when the ignition is on, anything orange should be hot all the time.

Can’t remember back up light wire color off top of my head but I went the other way with transmissions, started SM465 and now have an automatic. I’ll look when I get home tonight if needed
 

squaredeal91

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I don't have the column shifter in so when I turned it i felt no resistance and don't think it was doing anything. Ill have to put the shifter back in and try again. I would have done that yesterday but I was busy pulling out an engine in a subaru.
 

Matt69olds

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At the base of the column look for a 2 wire connector body. One wire will be blue (hot with the ignition on, powered by the turn signal fuse) the other will be light green.

Turn the key on, use a fused jumper wire to jumper those 2 wires, the backup lights should come on.
 

squaredeal91

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Thank you for all the help guys, ill try this next chance I get. My backup light switch for the transmission has arrived and ive got some replacement backup lights to go in as well now.
 

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