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hello, im unsure how to proceed. 17 ram 3500 6.4 hemi is intermittently loosing reference voltage #2. when it does, it sets a p1628 and p0344. there were no physical signs of damage to any wire loom for any of the sensors that the circuit serves. so i overlaid a complete new circuit for the voltage wire. now it seems that it does it more. it gets worse when warm, but as soon as the voltage drops out, i loose TB control and its in limp mode. ive traced it down to wires going to either of the pcm connectors. i pulled the wire loom away to see if i can see any signs of broken wire, as this suggests, but i cant see anything. i feel like the break is somewhere in that area but i have a hard time pulling the trigger on a new engine harness. anyone have any other suggestions on how i might be able to track down my break? its hard to verify even pulling on individual wires because they end up barely moving others. plus, only mostly doing it while hot and after the initial fault has me perplexed as well.
What’s all on the 5 volt reference line your losing? You could do what hardtop said. Or you can backprobe the pcm at 5 volt ref 2 and a sensor on 5 volt ref 2 if you keep it at the pcm and lose it at the sensor the issue is the wiring. You’d need a 2 channel scope minimum though. If you lose it at both cut the wire at the pcm to eliminate a sensor or short to ground.
I took the time to overlay the entire circuit. The problem isn’t the 5 volt reference circuit. I can only unplug the egr and trans line pressure sensor that’s on that circuit. Map unplugged won’t run, cam unplugged and of course, TB unplugged won’t run.
bandrauto wrote: I can only unplug the egr and trans line pressure sensor that’s on that circuit. Map unplugged won’t run, cam unplugged and of course, TB unplugged won’t run.
Have you taken a voltage measurement to verify the 5v supply or are you just going by the trouble code?
Given the p0344, I'd probably start my checks at the cam sensor and work my way back to the PCM.
If Your are losing the 5v ref you can monitor the voltage at the PCM key on engine off to see if it returns when you disconnect those items.
