Trouble Wiring Auxiliary B/U Lights with SPST Switch

Hi all. I have a set of LED lamps I installed for auxiliary backup lamps according to the attached diagram using a SPST switch with an LED on indicator, two diodes, and a four pin relay. My switched power is constant (not acc). With it wired this way, I get (only) the factory back up lamps when in reverse. If I turn on the rear aux lamp switch, the aux lamps come on. If I am also in reverse, the reverse lamps will come on as well.

My understanding of this diagram was my switch should have given me the option of:
1. powering my auxiliary lamps ON by manual switch.
2. With switch off, my auxiliary lamps would come ON automatically with my factory reverse signal lamps.

That's clearly not the case. Any ideas what happened? Disclosure: I can follow simple wiring and discussion but my head gets fuzzy in a hurry with theory or jargon. I appreciate any light you can shed on this (yes, pun intended).

BTW, I would like like to stick with the SPST switch just because I have a mated pair in the dash.

 

are you running the battery power for the relay (pin 87 usually) through the switch?

you need to run the fused batt power directly to the relay (Pin 87) and run a powered wire from the switch to pin 86 on the relay. you will need the diode isolate the wire.

reverse wire also needs to run to pin 86, diode isolate also.

 

The reverse wire runs to pin 86, diode isolated exactly as shown in the diagram. I ran fused battery power to relay pin 30, and pin 87 runs to auxiliary lights. I believe you are suggesting vice versa. Will that make a difference?

 

The power to the lights are just fine the way you have them connected. Those 2 pins can be swapped with no problem.

 

I'm Actually guilty of not looking at the diagram. I just read what you wrote. I would take a look at that diode and confirm which way it is wired. That is a one way "valve".... I think it is either bad or soldered backwards. You can temporary bypass the diode to see if the lights work correctly.

 

So what happens or not now when in reverse or you throw the switch?

 

When in reverse, the factory reverse lights operate. If I turn the SPST switch to on, the auxiliary lights will also operate at the same time, or separately if I'm not in reverse when I throw switch.

 

So what your saying is it works as planned? Then what is the problem?

 

He is having an issue aux light not activating when in reverse.

 

My understanding of that wiring schematic was SPST switch would allow for:
1. powering my auxiliary lamps ON by manual switch. Or,
2. With SPST in off position, my auxiliary lamps should come ON automatically with my factory reverse signal lamps.

But in actual practice, when the SPST is in off position and I put the truck in reverse, only the factory reverse lights come on, not (also) the auxiliary lights. In order to activate auxiliary lights, I need to turn the SPST switch on manually.

So am I misunderstanding what that wiring schematic is capable of doing?

 

I tied into the backup wire at the connector under the driver seat. It is red w/black stripe and tested positive for power when switched into reverse. The diode ties into that reverse wire at the (bear with my technical description) long side of the diode. The little band faces into the splice wire that will go on to the relay #86 pin.

I wired this thing exactly as the schematic shows. How sensitive are these diodes? I mean, I am okay with a soldering iron, but if they are easily damaged by heat maybe that is the failure? If they fail do they fail open? I know nothing about these gismos. The ones I used are IN4004 IIRC.

 

you may have a bad diode.... jumper the wire to check if the aux lights turn on in reverse. make sure you have the switch in the off position.

make sure you have a good connection...with the wires

diodes due fail in the open position

 

a side question.... is the diode for the reverse wire connected to the "switch" wire before the diode for the switch wire or do you have it connected in a "Y" configuration?

 

Yes. Diode for reverse wire is first, not in a "Y".

So today I swapped out both diodes and was still getting nowhere. "It's a mystery Scooby!" I finally gave up and wired the SPST switch to simple power and lights and took the reverse loop, relay, and diodes out of the equation. It just isn't worth anymore time spent on it.

Thank you to all who weighed in on this. I do appreciate your help.