Hey guys, I just purchased a 2000 Ram 2500 5.9L 4x4. I love the truck but when I bought it the fuel gauge did not work, I just assumed it was a sending unit. Well I replaced the fuel pump, gas gauge still does not work. I have verified that there is 12v at the fuel pump connector on the Blue/white wire, which is supposed to be the fuel gauge signal from the PCM. I went to the yard and grabbed a cluster and swapped it out. Same issue. I have ran the cluster test, the orignial cluster passes, so does the replacement. I have since switched back to the original. Turning the key on and off 3 times gave me a P0463, which is an open circuit for the fuel level signal circuit. But I have 12v, and ground at the connector. I am out of options on this one, do you guys have any suggestions?

Also, here are 2 other symptoms that are happening, when the cruise control is turned on, and throttle is applied, the fuel gauge reads full. When throttle is released, gauge will read empty. But only after the cruise control has been turned on. Also the coolant temperature gauge will not show a temp any higher than about a 1/3 of the way ~150 degrees even though the heat is strong.

What do you guys think?

 

How are you with wiring diagrams? You can download the factory service manual from here. Wiring diagrams are in section 8W.

I suspect the cruise circuit is backfeeding into the PCM somewhere..... Check the connectors at the PCM first.

 

Pretty good, that FSM was the first thing I grabbed when I purchased the truck. Going through the wiring diagrams the cruise, TPS, and fuel gauge circuit all share the same ground. I am starting to suspect the PCM is shot. But I always get suspicious about computers because they are expensive and typically not the problem. How are the computers on these trucks? are they a frequent issue?

 

No more so than anything else.... I would have a long, hard, look at that ground though.

 

After going through the 3 grounds in the joint connector in the PDB, they all show 2.7k ohms to ground, these grounds go to the PCM so I am thinking thats the reason they are not 0 ohms to ground. But when I measured the resistance to ground at the fuel pump connector for the wire that is supposed to go to the PCM ground, it was a dead short. So I am going to have to spend some time tracing the wire from the pump connector back to the PDB and see if it is shorted to ground. I will update my findings. If anyone has any other suggestions or input let me know.