Reverse fuse? Is there one?

Do any of the fuses in the smart junction box come on when the car is in reverse? Or are there fuses anywhere in the car that come on with the reverse? Thanks!

Not really. The reverse lights are turned on by the PCM detecting reverse, and the SJB sends the voltage to the reverse lights.
The PCM detects when the transmission is in reverse to do that.

There is a fuse for the lights, but it also protects other lights as well.

What problems are you having? If you are having any kind of shifting-into-reverse problems, that's not an electrical issue. Reverse lights would be electrical of course.

TexasBlownV8 said:

Not really. The reverse lights are turned on by the PCM detecting reverse, and the SJB sends the voltage to the reverse lights.
The PCM detects when the transmission is in reverse to do that.

There is a fuse for the lights, but it also protects other lights as well.

What problems are you having? If you are having any kind of shifting-into-reverse problems, that's not an electrical issue. Reverse lights would be electrical of course.

Click to expand...

I am looking for a source for my backup camera activation. Right now I have to click to turn it on but there is a trigger wire that'll turn on the camera when I put the car in reverse. It's wired into the reverse light but not working.

Manual or automatic?

For a manual, it's a little easier to tap into the reverse switch circuit. But tapping into the backup lights is a reasonable option, and is one I'm using for something on one of my cars. Keep in mind that many of the Ford circuits are "activated" by completing the ground on the 'return side' of the circuit, while providing a constant 12v power to the circuit when the key is on. When the circuit is "off", the ground "floats", so measuring both sides of the device (bulb, relay, etc) with a voltmeter would show 12v on both sides, but then when the bulb for example is on, one side will be 0v.

I dont remember if the circuit for the backup lights are like this, where the sjb activates the lights by grounding them and a separate power feed provides the voltage to them, or if the lights are grounded and the sjb feeds power to turn them on.
Once you know what it's doing, you should be able to get your camera wired in properly.

For a link to the wiring, look in the stick section of this and the 4.6L/V8 thread for the online service manual which has wiring diagrams. The lights wiring is the same for GT and V6 models, so you should be able to find the diagram and see what's what.

It's an automatic

Then yes, your best bet is to trigger off of the backup lights. The PCM uses the DTR (Digital Transmission Range) switch on the transmission to detect the current gear, and handle everything else, including telling the SJB to activate the backup lights.

PCM?

ECM, PCM, the main computer module under the coolant tank on passenger side under the hood.