reverse lights

[Tekemp]

I need some opinions i have some LED lights im going to use for reverse lights and i was originally going to wire them just to the upfitter switch and turn them on and off manually. My question is if i wire them like that and then tap a wire to the signal wire going to the relay from the factory reverse lights would i need to install two diodes, one on each side to prevent backfeeding. That way they would come on with the factory reverse lights and by the switch if i wanted.

Thanks, Tommy

 

[HOOV3R]

That"ll work fine. Exactly what I plan on doing with my duallies.

 

[Tekemp]

That"ll work fine. Exactly what I plan on doing with my duallies.

you mean using one diode on either side?

 

[HOOV3R]

Two diodes. Unless you want your upfitter light to come on everytime your reverse lights come on or reverse lights come on with the upfitter.

 

[Tekemp]

ok i understand thanks! Is there any special diode or can i just get some from radio shack?

 

[HOOV3R]

No problem. Yep, just a regular diode from radioshack.

 

[TERRCO]

I have no experience with the up fitter switches. What exactly comes on them other than what they run? If there just switches I see no reason to run a diode. If anything if the upfitter has a light indicator than it will illuminate when truck is in reverse. If that bothers you then yes put one diode between the switch and the reverse light. Also on your vehicle do the reverse lights have a constant ground signal or positive signal when off?

 

[Snake]

Upfitter switches are powered. Without a diode, you'll backfeed current. It may not be enough to cause a problem, or maybe it is. A diode is very cheap insurance.

 

[TERRCO]

Ok so what is the upfitter switch rated to handle? I usually never run anything off a switch. I only use a switch to run a relay. I still don't see a problem back feeding. Your trying to power lights off a switch on one circuit. If your not confident that that circuit can handle the amperage draw without blowing a fuse then why do it? If your confident that it will handle then how will back feeding cause a problem in the circuit? Only reason for a diode IMO if you don't want the reverse lights on when you turn the upfitter switch on. If that's the case then just one diode.

 

[Snake]

What about the upfitter backfeeding the reverse light circuit? It's been a long time since I did this mod and can't remember what relays, fuses, and other electrical components are on the schematic. But I do know you want power going to the lights and not in other directions. Easiest way to do that is with diodes. Why let power go in a direction you don't want it to?

 

[TERRCO]

"Scratching my head here" . Lets see if I can explain this. Positive is always seeking a ground. Ok? When something is using power it is in a sense making a loop between the positive and negative. Now depending how much power the device needs is how much current it will try and draw through a wire. Circuits have fuses to keep from too much current being drawn through the particular wire size and causing a fire. If the reverse light circuit was not strong enough to carry the load of the extra lights along with the reverse lights then you would pop a fuse which you said you have done this mod. You see you are running power in different directions at different times with no problems. The fact that the diode is there does not do anything other than keeping the reverse lights from coming on when you hit the switch. Power has run in both directions. Make sense?

 

[Snake]

It makes sense, and I understood what you were saying before. I haven't blown a fuse yet, but I also installed two diodes when I did this mod several years ago. The point of installing diodes in this instance is to prevent what might happen. Cheap insurance. I don't know what other electrical components might be impacted because I don't have a wiring schematic in front of me. You won't hurt anything by installing the diodes, but it may be possible to damage something by not installing them.

FWIW, I didn't tie the extra lights directly into my reverse light wire. I used the reverse light wire to trigger a relay. The upfitter switch also triggers the same relay using the same trigger wire. In other words, a relay whose trigger wire is shared by the upfitter switch and the reverse light wire. Hopefully that made sense.

 

[HOOV3R]

I would rather be safe and spend the extra $4 on diodes. Back feeding a circuit can cause some major issues, especially if you back feed the pcm.

 

[TERRCO]

To the OP. There is no regular diode from Radio Shack. You need to buy one with a zener rating of at least 17 since it sounds like you might be on the what if side. A diode is not cheap insurance. A fusible link is cheap insurance. Since you will be going to Radio Shack I would buy part number nte5077a. This has a zener of 18. Tolerance rated at 5 so this is pretty safe. You could go with nte5076a which has a Zener of 17. If what if happens this Diode will be useless. A bad regulator on an alternator will render the diodes useles unless the Zener is very high. The only problem back feeding a PCM would might remotely be the possible chance that you are going down the road and hit the switch and the PCM thinks the trans is in reverse. There are hundreds of diodes at Radio Shack. If you think that it is not possible for voltage to travel in both ways through a diode your wrong. I know this sounds kinda like I'm being a dik but I hate for you to buy the wrong part just going by what you heard. If I'm wrong someone tell me. I'll gladly shut up.

 

[HOOV3R]

To the OP. There is no regular diode from Radio Shack. You need to buy one with a zener rating of at least 17 since it sounds like you might be on the what if side. A diode is not cheap insurance. A fusible link is cheap insurance. Since you will be going to Radio Shack I would buy part number nte5077a. This has a zener of 18. Tolerance rated at 5 so this is pretty safe. You could go with nte5076a which has a Zener of 17. If what if happens this Diode will be useless. A bad regulator on an alternator will render the diodes useles unless the Zener is very high. The only problem back feeding a PCM would might remotely be the possible chance that you are going down the road and hit the switch and the PCM thinks the trans is in reverse. There are hundreds of diodes at Radio Shack. If you think that it is not possible for voltage to travel in both ways through a diode your wrong. I know this sounds kinda like I'm being a dik but I hate for you to buy the wrong part just going by what you heard. If I'm wrong someone tell me. I'll gladly shut up.

You're not being a dick, I should have been more clear in what I said. I should have went into zener ratings a tolerances in my reply, but I just made a very quick reply. Sorry for the confusion on the type of diodes, was referring to zener diodes as the commonly used standard diode. My bad if I confused anybody.

 

[Ron's Power Stroke]

I did mine like this..there should not be any back feed through the upfitter if it is in the off position..