I hooked up accesory back up lights by tapping into the back up wire under the drivers seat. I have them switched to come on with the backup lights and to come on by themselves. They worked for a month or two then a couple weeks ago i was home and noticed that when i put it in reverse none of my back up lights came on. but I can still switch the new lights on by themselves so there is a problem with my stock backup light circuit. i checked the fuse in the cab which i believe is #27 and it was fine and i checked the fuses under the hood for all of the lights and they are all still good. So what else should i check? Im not really sure where to go from here to solve this problem.

 

Ground? Or you could have burned out the power wire for those.

 

Do you have your extra lights and stock lights running off same power wire when in reverse and another power wire strictly for when you switch them on manually?

 

Burnt out the stock wiring? The ground hasnt changed for the stock back up lights so i dont see how that would be the problem.

 

No they arent running on the same wire when they are both on. i tapped into the stock wireing in the cab and that goes to the switch with a 3amp fuse on it and then the switch goes to a relay under the hood that runs the new lights. The only thing i can think might have happened is my switches were in a jumbled mess and they could have touched each other.

 

Yeah if you have too much running through the stock wiring it could fry that wiring. Only way to find out if its yes or no would be to track the whole wire. But I would just check around the connection where you tapped in. Maybe it could be as simple as a loose connection.

 

If i fried the whole wire and have to replace im going to be pissed! shouldnt the fuse blow before the wire burns out? but i was thinking of checking the connectionand see if i cut the wire with the tap connector. But i cant do anything till friday when i get back home, just trying to get ideas to check when i get home.

 

I would think that the fuse or relay would blow first yes but I have heard of the power wires burning out so thats why I threw it out there. Could just be a bad connection.

 

ok, well thats what im going to hope for. My brother and his friends used my truck between the time when it was working and when it wasnt so maybe he stepped on the connector or did something to it on accident. He is an electrician so i will make him help me with it.

 

Ok i got home and started working on it. found out that the reverse switch is still good and power is still going through the fuse too. the owners manual says its fuse 27 and that it is supposed to be a 15 amp fuse but there is a 30 amp in the slot should i change it?

So now to narrow the problem down does the power come from the distrobution box under the hood to the transmission then back up an to the fuse box in the cab and then from there down through the floor and to the back up lights?

if so we have power to the fuse box but we dont have power to the wire before it goes through the floor in the cab. if this is how the circuit works out how do you get to the wire harness that goes from the fuse box down to the floor?

Here is a pic of where we dont have power too, which is where i hooked my new lights up to get power to turn on with the stock lighting.

 

30 amp in a 15s place. Could melt wire for sure.

I wouldn't imagine it's much load to kick the relay though.

 

Think we found the problem. I remembered that i have the ford shop manuals for my truck so i looked up the back up light diagnosis section. It said to check the backup lamp switch to ground resistance and if <5 ohms then replace, it turns out it is 4.6 omhs so i will be going to town tonight to pick up a new for 13 bucks and hopefully it fixes the problem. I will let you guys know.

 

That red splice connector I see with the black wire and shrink tubing on it, is that the power to the auxillary lights? It is possible that it may have cut the factory wiring because of the design. If that is the case, I would just repair it. I hope you find the problem and let us know what it was.

 

yes it is the power to switch the auxillary lights on with the factory backup lights. I thought that might be the problem but i took that connector off and the wire is still in one piece but i think i will be replacing it. probably try to pick up a 3 way connector will im in town tonight.

 

Yeah, I have had those connectors cut the wiring in the past so I don't use them. I will be watching all this info since in the future I want to do this as well. (Good pics by the way!). Right now I am in the process of replacing my fuel pump which I will get tomorrow. Got the bed off (glad I don't have to drop the tank!)

 

First and foremost ensure you have a good fuse in socket 27 of the fuse block and yes put the factory rated fuse in place of the 30 you found. Next If your truck has a manual transmission the switch on the tranny should have a two wire connector. One wire may be a Violet with Orange stripe and the other a Black with Pink stripe. The Violet with Orange stripe provides power via Fuse 27 with the ignition on.

When you place the transmission in reveres the switch closes allowing power to flow back through the Black with Pink stripe wire through the cab via connection 110 on the firewall to where you spliced into it and then back out of the cab to the back-up lamps.

If you disconnect the tranny switch, with the key on, there should be power on the Violet with Orange stripe wire. If not, you'll need to back trace that wire to fuse 27. If you have power, use a jumper wire between the two terminals and see if your back-up lights now come on. If so, the switch is probably bad. If not, then check for power where you spliced in. If you don't have power there, then there's a break in the wire between the tranny switch and the point where you spliced in. Follow the harness from the transmission through the engine compartment to the firewall looking for any signs of damage. If none, follow the Black with Pink stripe wire back to the firewall looking for any signs of damage. Be sure to check all connectors under the floor mattes that these wire run through for signs of corrosion or melting.

Hope this helps,

Rev

 

Thanks for the info! would have been tons of help the other day but the backup light switch on the tranny was bad. I replaced it and they work now. Thanks everyone for the help

 

I didn’t read all of the posts, how did this work out for you ?

Just a couple of things:

1) The OEM wiring for the bakup lights should only be used to activate a relay, that in turn turns on the new aft mkt lights. Ford and its better ideas used wire gauges just big enough to work the OEM component.

2) ALWAYS use a relay under the hood and a fused power wire for any add-on lighting.

 

Yep did both of those. and the post above yours i said that the switch on the transmission was bad. So its all working fine now!

 

As said didn't read all of above.

Good to use relays and fuses.

Good that you got it fixed.

Ltr

 

just giving you a hard time man. thanks for the advice!