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I'm trying to diagnose an 04 Ram 1500 Hemi that all of a sudden would not crank. Friend had it towed home where I notice when turning the key to start, no sound(no solenoid click). Using wiring diagram, I had power up to the starter relay, but no ground. If I provide the ground and turn the key to start, it will crank. In looking at many wiring diagrams, I'm thinking the ground goes through the Transmission Range selector (45RFE trans) with switch inside the trans on valve body, but not sure since I don't have that wiring diagram, just Chiltons.

Other things I noticed (that the friend said happened at the same time):
1. Speedo and Tach sweep to full clockwise and stay there while key is on.
2. If I move gear shifter while stepping on brake with key on, there is no gear range indicator. Shows the P-R-N-D etc but no idication which position it's in. I verfied that the transmission lever is physically moving at the trans side.
3.When I hook up two code scanners to the OBD2 port, both come back after trying to negotiate the protocol that there is no communication with the vehicle. Verified there is gnd on pin 5 and +12 at pin 16 of the DLC.
4. I can hear the fuel pump and ASD relays cycling on-off-on-off as long as the key is turned on. Tried swapping relays(starter relay earlier, ASD and Fuel pump) with identical ones, same result. I see voltage fluctuate when the relays pick while they are cycling on and off.
5. Undid all the fuse box and PCM connectors to look for corrosion and loosened an re-tightened all the grounds that I could see in the engine compartment. Pulled each fuse out to visually inspect.
I'm tired and lost...any ideas?
thanks guys.

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Has there been a tuner installed ever on the truck and has it been recently changed or tampered with? I'm leaning towards to computer has freaked out seeing you have checked most of the common issues.

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Computer problem.

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+1 on computer.

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Thanks for the responses. I checked things based on things I've read from this forum. Kudos to all of you guys. As for any mods, no, this truck is bone stock. Not even an aftermarket alarm system. Get this, I also noticed that if you leave the key in the on position for at least 20 seconds, the odometer increments 1 mile. I'm guessing because the speedo is registering 120mph! I'd like to be able to diagnose the PCM before swapping out, but I guess this is so weird that I might have to easter egg this one. Thanks again for your thoughts. Any other ideas?

What in the world??? lol that is crazy!! I have never heard of that happening, it's gotta be the PCM I would think..?

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Might need it reflashed. For some reason I recall there being a PCM problem on certain part numbers. Check with your local dealer to see what they charge to reflash the computer.

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Thanks, will look into that or buying a refurbished and guaranteed PCM to see which is more feasible. I was hoping it's some sort of bad power or ground to the PCM, but not real anxious to go through that exercise unless I have great instructions and diagrams for locations.

Thanks all for your input. I will post back if/when I get the fix. (might end up sending the friend to a dealership).

Well, I was able to get a PCM from an identical truck for testing. It started immediately without any of the symptoms I noted before. I guess a choice would be to have the dealership reflash the "new" PCM with the VIN and mileage or get one online someplace. I just wanted to feedback that the PCM was the problem in my case. Whew!

Thank you all for you input and comments. You guys nailed it.

Good deal man, stick around and have some fun.

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