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When I put the truck into reverse, my reverse lights don't illuminate. The truck's computer knows it's in reverse because my backup sensor works fine. Could this be the reverse switch on the transmission? What else should I check?
I suspect the PCM gets its reading from the switch on the transmission.
Have you confirmed the bulbs are good?
The lights were intermittent working / not working for about a week before they stopped all together. That tells me it's probably not the bulbs but Ill check them anyway.
If the pcm and the tranny switch work together, could it be wiring behind the bumper? It would be odd for both lights to go out at the same time; although not impossible
Power to the backup lamps goes through the digital transmission range sensor (DTR) on an automatic transmission. Yours is probably bad. Here is the wiring diagram. https://charm.li/Ford/2002/F%20250%2...Backup%20Lamp/
The lights were intermittent working / not working for about a week before they stopped all together. That tells me it's probably not the bulbs but Ill check them anyway.
In this case I’d suspect a break/short in the wiring.
I understand what Don is saying, but at this point I can’t grasp why the backup sensors would work (PCM sees reverse) if the switch is bad. Unless the light goes through a different pin than the PCM signal.
I’d like to see how the signal goes from the switch to the PCM and rear of truck. I still feel the switch is likely ok since your PCM is seeing Reverse signal but I’m just speculating since I don’t know the circuitry.
But the switch would be a simple check once google tells you what pins to confirm. You’d just be looking for continuity between pins of the switch itself.
Here's the DTR wiring. There are separate switches inside the unit to send signals to different places. The diagram shows the pin number and wire color to test.
Here's the DTR wiring. There are separate switches inside the unit to send signals to different places. The diagram shows the pin number and wire color to test.
Here's the DTR wiring. There are separate switches inside the unit to send signals to different places. The diagram shows the pin number and wire color to test.
Thank you for the diagram!
So the consensus is the reverse switch on the transmission tells the PCM the truck is in reverse and actuates the reverse sensors. And the Digital Transmission Range Selector actuates the reverse lights which is where I need to start my investigation.
Thank you for the diagram!
So the consensus is the reverse switch on the transmission tells the PCM the truck is in reverse and actuates the reverse sensors. And the Digital Transmission Range Selector actuates the reverse lights which is where I need to start my investigation.
An automatic has the DTR sensor only, and a manual has the switch.
