4.7L cranks, won't start
Hi! Hope the forum can help out here.
First things first, forum etiquette being what it is, I did do a search in this forum for this specific problem, and didn't have any luck.
My friend has a 2001 Dodge Dakota with the 4.7L engine.
The truck ran absolutely fine up until one day. Vehicle driven, parked, then wouldn't start.
The "problem" indications are that none of the gauges work (fuel, temp, etc.), the overhead console display comes on, but everything is zeroed out (battery has been disconnected...reason for this?). The compass MIGHT work. The gauge display says "no bus". The fuel pump does not prime when key turned to run. The engine turns over, but obviously doesn't start. Fuel pump does not run as the engine cranks. I checked the fuel rail pressure test port, and after a week or more of sitting, and intermittent attempts to start it, the fuel rail STILL had pressure (no pressure tester, just pushed in the valve and fuel came out under pressure), leading me to believe that the injectors are not being commanded to fire when the engine is turning over (probably same issue not causing fuel pump to run?). The PCM connectors have not been removed/cleaned/inspected yet.
The fuel pump relay has been swapped with the AC one (which works) and that didn't fix it. Key on/off/on/off/on threw codes "999", "920" and "921" if I remember correctly.
The owner had already pulled the bed off and purchased a fuel pump, so we swapped that, of course it wasn't the problem. But it gave me a good chance to do a rudimentary check of the wiring harness, and what I could see looked good. All the loom is intact, all the loom is still attached well to the body, all grounds I could see are tight and clean (to include up at the PCM). The truck has never exhibited any "random" problems before that lead me to believe it might be wiring or something else that wore through, or a ground that failed for whatever reason, etc. No recent work done on it.
The truck has lived in the NW for most of it's life, so there is no rust/corrosion to speak of, and based on the undercarriage and owners testimony, the truck has not been abused.
The owner has a copy of the service manual, but it's in PDF and a bit difficult to reference, not being hard copy. I don't know how to check for spark with this setup since it doesn't have plug wires. I expect no spark if the pump isn't being commanded to run...?
Appreciate any advice you might be able to give!