No, not really. The temperature sensors are simply resistors that chance resistance with temperature. Internally the PCM measures voltage drop across another fixed resistor. Depending on the resistance of the temp sensor the current through the fixed resistor changes which in turn changes the voltage drop. The fuel gauge works basically the same way except the resistance changes with the fuel level. That means even if the temp sensor is shorted to ground, it will not kill 5V supply for cam, crank, TPS, MAP. However the PCM would read a very high temperature, that's why I asked what the temps read.

Circling back to the original problem, there's just a lot going on. MoparFanatic: Did the truck have these/similar issues before the fuel pump was changed ? Also, why was the fuel pump changed ? Sounds like a stupid question but I'm curious if it didn't run, or low pressure/hard starts like now.

Can you check one thing: Put a voltmeter between the engine (red/pos lead) and the negative battery post. See if there is any significant voltage drop during cranking.

 

So he bought the truck and it had a problem of dying when put into reverse. You had to hold the pedal to get it to go. Then it had a problem of dying and the odometer said "No bus". Well he didn't want to wait for me to look at it on the weekend and took it to a mechanic. He threw a fuel pump in, trans harness, and fixed some wiring running to the PCM. (Did a ****ty job just twisted them together with no insulation. NONE.) It ran good for a while and this happened. I told him to unplug the O2 sensors a while back it ran fine he plugged them back in town fine for a few months and here we are. I only know the truck has two issues according to the check engine light. A moderate evap leak and you can't fill the fuel tank up because it leaks (I think it's the filter neck).

I went to look at the truck tonight and he dropped it off at the same mechanic. I will update with what the mechanic found. I had a strategy in my head but it sucks as a lot of my high end tools are out getting repaired. My DRBlll and my scope are down. I'm thinking about getting that new wifi tool but don't know if it would work on pre Can Bus vehicles.

 

The plot thickens I'd say whatever the mechanic did did not get to the root cause of the issues. I'd start with the basics, power and grounds especially if the truck is from the rust belt (the test I described above finds grounds that can't carry enough current). Look closely at the PDC and check for corrosion in fuse and relay sockets. Then double check all the wiring repairs and wiring in general. Maybe do a wiggle test with the engine harnesses and see if you can get the cluster to go in and out. If trans harness refers to the inside wiring, disconnect the trans in case it wasn't done right. If that all checks out the scan tool might come in handy. If WiFi means the micropod II clones with the DRBIII emulator it's supposed to work with older vehicles (the factory ones do) but all you can find on the web are people using it with early can-bus vehicles. Many of the clones don't work correctly so I stayed away from them so far.

 

The mechanic is super to fix it but when he first had no bus happen (in the summer) I wiggled the plug in the fuse box and it cause it. Don't know what trans harness he replaced.

The tool I was going to buy an actual Wi Tech scan tool. I will keep this thread updated! Like I said I had a plan in my head but it helps to get help from someone not cursing at the truck.

 

It's still on the 5v regulated ref circuit just not the same external circuit/wire. It's internal to the PCM. Pretty sure.

How's your battery connection? I had the same issue of having to hold down the accelerator in the past and cleaning battery connections always fixed it.