Rocker switch hooked up but LED will not light up. ?? (1 Viewer)

[BullElk]

I have hooked up a three prong rocker switch with LED. The switch turns the back up light on as desired but the red LED on switch does not light up.

I have the brass to a proper ground (that does work with a test light). The middle prong to battery and the other promg to positive back up wire.

Any ideas?

I also get the p1780 code suggesting something wrong with AT gear selector.

 

[BullElk]

I am now driving and noticed when I flip the switch the transmission gears down just like pressing O/D off.

 

[Ayune]

You have a connection diagram for the rocker switch? Like how it’s supposed to be wired?

Also, where did you tap into the reverse light circuit?

 

[nukegoat]

Sounds miswired

 

[BullElk]

Looking at videos wiring the exact same switch. I’m wiring it up exactly the same way. The one brass prong is ground. The other two are positive and to the desired light. I’ve switched those two around and exact same thing happens. Back up lights on but LED not on.

I tapped into the positive wire right before the back up bulb.

 

[Ayune]

I see a diode in your future.

The wire that powers the Backup Lights (red-with-black-stripe) also goes into the Engine Control Module, telling it you've physically moved the shifter to "R".

So by manually injecting +12V into that wire the ECM thinks you've shifted into reverse and changes shift patterns, but gets confused and throws a code because, oh snap, the shifter is also in another gear.

You'll need to cut the Backup Light wire between the ECM and backup bulbs, insert a diode, then inject your switched +12V on the bulbs side of the diode. The diode prevents the +12V from back-feeding into the ECM.

And I'm not sure why the LED in the switch isn't lighting up. LEDs have polarity so perhaps it's being powered backwards.

 

[nukegoat]

I see a diode in your future.

The wire that powers the Backup Lights (red-with-black-stripe) also goes into the Engine Control Module, telling it you've physically moved the shifter to "R".

So by manually injecting +12V into that wire the ECM thinks you've shifted into reverse and changes shift patterns, but gets confused and throws a code because, oh snap, the shifter is also in another gear.

You'll need to cut the Backup Light wire between the ECM and backup bulbs, insert a diode, then inject your switched +12V on the bulbs side of the diode. The diode prevents the +12V from back-feeding into the ECM.

And I'm not sure why the LED in the switch isn't lighting up. LEDs have polarity so perhaps it's being powered backwards.

Could it be that he's got it wired backward altogether? LED isn't lighting up because the angry pixies are flowing the wrong way

 

[BullElk]

I have only one wire routed to the rear of vehicle because it was originally setup for trailer brakes by PO. I spliced that wire into the positive back up wire because I already have two additional LED bar lights spliced with each side of back up lights.

Due to only having one wire comimg from the battery, I cant wire it into each LED bar light.

 

[gatormark91]

Use a 5-pole Bosch-style relay. Wire it into the reverse light wire. When it sees the backup wire power, it will flip the relay and power your light circuit. That way it doesn't change the action of the original backup circuit. Cheap, couple of dollars at the auto parts store.

 

[Ayune]

I have only one wire routed to the rear of vehicle because it was originally setup for trailer brakes by PO. I spliced that wire into the positive back up wire because I already have two additional LED bar lights spliced with each side of back up lights.

Due to only having one wire comimg from the battery, I cant wire it into each LED bar light.

The other lights you have hanging off the Backup Light circuit aren't causing your tranny or switch LED issues. You are manually applying +12V to the Backup Light wire which confuses the ECM.

The only way to manually illuminate the Backup Lights without confusing the ECM is to separate the ECM from the bulbs with either a diode or relay.

Use a 5-pole Bosch-style relay. Wire it into the reverse light wire. When it sees the backup wire power, it will flip the relay and power your light circuit. That way it doesn't change the action of the original backup circuit. Cheap, couple of dollars at the auto parts store.

Anytime the bulbs get power (from a relay or otherwise) the ECM will also see power and get confused. The same wire physically connects the bulbs and ECM. You must separate the two with a diode, which can be thought of as a one-way valve for electricity.

 

[BullElk]

I decided to not connect switch wire into back up positive wire. Instead, I connected the switch wire to the positive of one of my LED bars then connected both LED bars together via positive wires. Now LED bars only come on with switch, not when reverse is selected. However, the little red light on switch still doesn't come on and it is the second switch I have tried.

I can now use switch when in reverse...as well as when locking a gate behind me at night or shining a tailgater on the interstate, among other things. Which is fine with me and very simple.

 

[BullElk]

Thanks for all of the information provided that I obviously knew nothing about.