I've read through other forums here didn't see the same problem I am having.

2004 6.0 f550 flat bed
Reverse lights and back up alarm out.

Fuses are good triple checked every fuse.
Relay is good checked and bought a new one.
Truck will not start in any gear but P or N
No reverse beeper or lights as I change through gears.
When I stick a wire in to the relay on post 3 and 5 effectively opening the relay I get reverse lights and beeper.

Pulled both wiring clusters off transmission no corrosion. I assume my range sensor is good since it will not start in D 123.
Assume grounds are good since when I wire open relay lights work. Grounds visually look good.

What should I check next

 

Put 12v to the relay at 86 and see if they come on

 

What do you mean at 86?
I jumped the relay and they do come on

 

The reversing lamps relay is activated by the PCM when it detects that the TorqShift has been placed in reverse as reported by the TRS.

You need to verify 1) that the PCM is getting the proper signal from the TRS (use a scan tool) and thn, it that is correct, 2) see if the PCM is properly commanding the relay to energize.

That would be called "assuming to be a fact something that is not in evidence" (yet). The TRS is not a simple switch, it's a sensor that sends a PWM signal to the PCM that has a variable pulse width output based on the position of the shift lever input. In the same maner, the sensor does report all other positions to the PCM which then controls whatever needs it.

Before digging into the PCM, I would first verify that you have switched battery power on pin 1 of the relay when the key is switched to RUN. When the relay is supposed to energize, the PCM is supposed to connect pin 2 to ground via a driver in the PCM you can check for that also, but you must do it with the load of the relay's coil in circuit between pins 1 & 2 of the socket.



This is not a common 5-pin relay with those terminal numbers. See schematic. The troubleshooting idea is valid as a quick check of part of the total circuit, it just needs to be adjusted for the different component and its pin labeling.

 

the fun and joy of computer controlled vehicles..

 

Yeah, and the system in this thread was designed 15 years ago...

But wait, it gets better! Look at the new stuff coming out. They're <bleeping> computer networks on wheels. WTF comes next, cloud-based control of the vehicle that will manage all the autonomous vehicles on the road simultaneously?

 

between computer SYSTEMS and no space for hands/arms

the reason I retired from the dealership.... ( Not Ford )
wait,,,, till they bring out the 36 volt systems... and micro wiring.. its coming

 

So?

Not seeing a problem here. Some people are going to have to learn how to troubleshoot, but that troubleshooting can be made much easier with the amount of data available.

It's all still the same process.

 

It all comes down to one word (obsolescence) the car manufacturers are treating their vehicles like computers, you buy a PC it has a 1 year warranty, unless you buy an extended warranty for another 2 years. Once the warranties are up, they don't want to deal with you anymore, unless you buy another new vehicle from them.

It's easy, right? Ford has the extended warranty for 100,000 miles average person now days put 20,000 - 25,000 mile on the vehicle a year so in 4 years, you should be ready to trade in on a $40,000 - $60,000 truck (Every 4 years) So other than regular maintenance and uncovered repairs, the vehicle is only costing you $10,000 - $15,000 a year to drive. Not a bad deal for a computer on wheels, right?

 

and there is the reason I purchase "XL"......

and I can work on the car computer stuff.