wiring a relay

[Mitch.E]

I understand that to switch on a back up camera the wiring from the reverse light has to be changed from minus to plus through a relay. Hoping someone could explain exactly how to do it. The relay pole numbers confuse me. Mitch E

[carntz]

I understand that to switch on a back up camera the wiring from the reverse light has to be changed from minus to plus through a relay. Hoping someone could explain exactly how to do it. The relay pole numbers confuse me. Mitch E

When I had mine done all that was needed was a inline diode, which the stereo shop forgot to install and with the help of of Steelblue we got it solved.

[Frank Dreano]

I don't think this is a diode issue; unlike many cars the retro TBird has constant voltage to the backup light bulb with the key on and sends a ground to the light when the gearshift is in reverse, via the REM (Rear Electronic Module), to complete the circuit and turn the bulb on (e.g. a negative "trigger"), many radios (e.g. Kenwood and others) expect a positive "trigger" to activate the backup camera on the screen.

Therefore a relay wired to reverse the TBird's "trigger" to the radio is required. All that is needed is two wire connections to the backup light and a short jumper wire.

This should be how you wire it up. Since you are only supplying a small trigger 12V output to the radio the backup light 12V socket wire can supply both the relay power and trigger voltage via a jumper at the relay (green wire in diagram) - this also has the additional advantage of only powering the relay when the key is on.

This 12V signal will be sent to the radio (pin 87) when the OTHER wire at the backup light socket (pin 85) goes to 0V when the gearshift is in reverse and switches the relay.


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The orange/black driver's side backup light wire should go to the jumpered 86/30 relay connections and the black/green wire to pin 85 on the relay but YOU SHOULD CONFIRM THIS.
Backup_Lights.PNG

You can confirm which wire is +12V and which goes negative at the backup light socket...that can be determined by putting the car in reverse with the key on and engine OFF (parking brake on) and finding the 12V wire at the backup light socket - the other wire should not read 12V and is the "trigger".

You will have to splice into the the two backup light socket wires to do this; peel back about 2" of the electrical tape wrap and strip the two wires (WITH THE KEY OFF) and solder the connections or use wire taps (which I don't really care much for).

I mounted the relay on sticky Velcro tape to the inside of the driver's side fender behind the trunk liner panel...

[steelblue5505]

Frank, nice write up.

[Mitch.E]

Thank you Frank. Just what I was looking for. Mitch

[Tbear]

If you have a Pioneer, then there is likely a setting change you can make in the radio setup. One of the reasons I bought a Pioneer just because the it was easy to make this change.