2004 Dodge Ram 5.9 diesel no start bad wirings
Me and my buddy were working on this diesel engine over the weekend because it would not start. Battery is good and using the engine ecm diagram you recommended; we checked the power and ground supplies and were ok. By accident, it started after we wiggled the wires in the wiring harness and this is why we suspect, it is a wiring problem. The harness is located on top of engine near the tps sensor. Not sure though?
This could be a wiring issue, check the 5 volt supply on the ecm terminal since this wire controls the crank and throttle accelerator pedal sensor (APS) which you need for starting. Any of this 5 volt supply wire is shorted or open can also can also cause the no start. To do a quick check at ecm, check for the 5 volt supply at pin 27 and pin 42 terminals. The pin 27 supplies 5 volt at crank sensor (dark blue wire) and pin 42 supplies 5 volt at pin 5 at APS violet pink wire. Do these at KOEO. If you don't have 5 volts at pin 28 and 42 at the ecm, then ecm is suspect. Try disconnecting these 2 ecm wires one at a time incase their respective wiring at the crank/APS sensor is no good.
Sometimes, if 5 volt supply is present only on one terminal pin, you can bypass the 2nd one by running a jumper wire from the available 5 volt source just to check if that circuit is OK. However, before doing this, run a quick check for continuity to the sensors in case the wires are shorted or it will kill the ecm.
If you suspect the problem is ground circuit, run a jumper wire from battery negative to the ecm pin 49 and pin 50 ground terminals and see if it starts. This engine is known to have loose terminal pin connectors and bad ground wires which should be tested thoroughly.
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