02 4.7 Died, At Wits End

[MrBman2000]

So I have a 2002 1500 with the 4.7, 4x4, around 240K miles on it. It belonged to my younger brother before I got it, he wasn't the best to it, I got it mostly to stop my dad from junking it. It's been a good truck up until around three weeks ago.

Three weeks ago it cut off driving down the road like it ran out of gas. Got it towed home, only code has been a P0340.

Replaced cam sensor twice, no dice. Replaced crank sensor, no dice. Tried another PCM, no dice. Wiring harness has been repaired so double checked the repairs, all were good except the harness being made of aluminum was different to me.

Then came the fun, I've swapped the relays around and fuses, still nothing, just cranks and cranks. Cleaned every connection I could find, cleaned the battery cable ends, tried a different battery, felt most of the harness down for bare spots, most of what any normal diagnostic should be.

Only things I've noticed is the OBD reader shows ZERO engine RPMS cranking it over, and it cranks normally, not too fast or anything. I'm about to try an engine harness in it. I've also heard about the ASD in the fusebox? I'm not a big Dodge guy but I really like this truck, it'll go anywhere and pull anything short of a house around.

 

[Fishstickz]

While standing outside your truck, turn the key to ON but don’t start it. Do you hear the fuel pump priming? It’d be a humming noise coming from around the drivers’ rear tire for about 5 seconds. If you dont hear anything from back there then the fuel pump is probably bad

Not saying this is for sure your issue, but these pumps work great up until they die without warning (although mine at least had the decency to let me drive all the way home before it quit lol)


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[tron67j]

Well, you could have a bad PCM that is not working right on that circuit and is causing the code. I would go changing that yet, you could also have a bad wire harness. You might want to check continuity to see if there is a broken or loose wire. I kept having a a code for a bad O2 sensor even after replacing it. Finally found the plug was bad even though I had tested it once. Good luck.

 

[Dodge 1500 4X4]

Check the Timing, They have been known for broken timing chain idlers, there's a guy on here that tore one down I'll see if I can find it.

Read This

https://www.ramforum.com/threads/4-7-rebuild-questions.167515/

 

[MrBman2000]

I do have a fuel pump running, and good pressure at the rail. The truck has no spark, I've tried two PCMs, one came out of a running and driving rust bucket of a truck, both have the same code, with no spark, and no engine RPMs when cranking.

I've debated the engine bay harness just being bad somewhere in it, since there's a few wires that have been ran over again from the plugs to the PCM connectors with aftermarket wires, so at some point it's given somebody a headache before.

I'll check the timing but I'm near positive it's in time still, last motor I had slip timing cranked really fast.

 

[Fishstickz]

I do have a fuel pump running, and good pressure at the rail. The truck has no spark, I've tried two PCMs, one came out of a running and driving rust bucket of a truck, both have the same code, with no spark, and no engine RPMs when cranking.

I've debated the engine bay harness just being bad somewhere in it, since there's a few wires that have been ran over again from the plugs to the PCM connectors with aftermarket wires, so at some point it's given somebody a headache before.

I'll check the timing but I'm near positive it's in time still, last motor I had slip timing cranked really fast.

This is quite a mystery then. I would say definitely check the wiring then, whoever ran the wiring may have done a not-so-great job running it lol. Hopefully its something simple like a broke wire or unseated connector


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[MrBman2000]

So I got a new engine harness, really clean one to put in. It’s off a truck built the same month so should be a direct swap. I have a question though.

all of the junkyards around here, the fuse boxes are gone. Why is that? People trying to diagnose a bad PCM or do they die often?

 

[Fishstickz]

So I got a new engine harness, really clean one to put in. It’s off a truck built the same month so should be a direct swap. I have a question though.

all of the junkyards around here, the fuse boxes are gone. Why is that? People trying to diagnose a bad PCM or do they die often?

There’s quite a few issues that can come from the fuse box. The fuse box is actually a whole computer called the TIPM (Totally Integrated Power Module). It’s the most important computer in the truck since literally EVERYTHING is powered by it, and it does have its share of problems. A lot of those problems are internal and can’t be fixed by yourself or the dealer, so you’re stuck buying a replacement. Anymore the junkyard is one of the few places to get one. Heck I’ve heard of times when the dealer uses junkyard TIPMs

Also, those things are worth a lot of money, wouldn’t be surprising if that junkyard pulled them theirselves to make some extra profit by selling them online


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[MrBman2000]

So pull the two good ones I know where are basically? Are they interchangeable from 02-05 trucks? I’d think so even among drivetrain options.

 

[Fast69Mopar]

So I have a 2002 1500 with the 4.7, 4x4, around 240K miles on it. It belonged to my younger brother before I got it, he wasn't the best to it, I got it mostly to stop my dad from junking it. It's been a good truck up until around three weeks ago.

Three weeks ago it cut off driving down the road like it ran out of gas. Got it towed home, only code has been a P0340.

Replaced cam sensor twice, no dice. Replaced crank sensor, no dice. Tried another PCM, no dice. Wiring harness has been repaired so double checked the repairs, all were good except the harness being made of aluminum was different to me.

Then came the fun, I've swapped the relays around and fuses, still nothing, just cranks and cranks. Cleaned every connection I could find, cleaned the battery cable ends, tried a different battery, felt most of the harness down for bare spots, most of what any normal diagnostic should be.

Only things I've noticed is the OBD reader shows ZERO engine RPMS cranking it over, and it cranks normally, not too fast or anything. I'm about to try an engine harness in it. I've also heard about the ASD in the fusebox? I'm not a big Dodge guy but I really like this truck, it'll go anywhere and pull anything short of a house around.

There are a couple of things I would do before replacing the engine wiring harness. First, I would download the 2002 Factory Service Manual from the 3rd Gen DIY Forum and look at the wiring diagram for the crank sensor. Check for continuity on the crank sensor signal circuit between the crank sensor connector and the PCM connector. Next, verify that you have a 5 volt supply at the cam and crank sensors. There are several other engine sensors on the 5 volt supply circuit. Any shorted sensor that is supplied 5 volts by the PCM can bring the circuit down. Ask me how I know. When the 2002 model year trucks were still on the dealership lots, I had one with a bad A/C low pressure switch that pulled the 5 volt supply down to 2.7 volts and the truck was a no-start right off of the transport truck. I was so mad for not checking it.

Also, the ASD relay circuit provides the B+ battery power to the coils. The ASD relay also aprovides B+ battery power to the fuel pump. If you hear the fuel pump running when you turn the ignition key to the run position then your ASD relay is being commanded on by the PCM.

Like one of the other posters said earlier, the timing system of the 4.7 can be an issue but it's not going to cause your scan tool to see zero cranking rpm because the crank sensor reads directly from the tone wheel that is fastened to the crankshaft. If you don't have any cranking rpm it can only be caused by a few things really.

 

[MrBman2000]

So update to this. The disaster of an engine harness is now replaced, it's off a nice clean truck and doesn't have 11 splices in it. With that said, still no go, but we've gotten somewhere.

With both PCMs, I have power at the camshaft sensor, but NO POWER at the crankshaft sensor, and by none I mean NONE. Obviously no power equals no engine RPMS. At least now I can do some diagnosis because all the wires aren't black and held together with various types of wiring crimps.

What I don't get, is why there's 5v at the camshaft sensor and nothing at the crankshaft sensor? They're supposedly the same supply of 5v.

I went to download the 3rd gen service manual just now, since I've been working a lot the past couple of days.

The only oddity I've noticed overall is the truck periodically will switch the fuel pump on by itself? Like if you leave it switched on just sitting there a little while, the fuel pump will go through the initial prime again. That's not normal.

 

[MrBman2000]

So I've got the wiring diagram found and apparently they share the 5v signal off literally the same wire. So the harness off a truck with a visibly dropped valve seat has a problem?

Meaning they drove the junked one with a bad valve? I'm still mid reading and such.

I'm still looking at the diagrams and all that, these FSMs aren't a joke, they even list the OEM tire brands and models lol.

 

[MrBman2000]

So best I can tell I've got it figured out. The 5v source wire comes from the PCM for both the cam and crank sensors, and goes through the sensors coming out of different pins. The wiring harnesses (both) have no continuity from the pin to the connection. The original up in the harness a short ways had been repaired, presumably because of this before. I haven't checked the grounding pins yet on the crankshaft connection to see if they're a complete connection from the PCM to the sensor.

Being as though both trucks were quad cab, built 9-2001, and had identical part numbers on the PCM, it stands to reason they were extremely close in sequence. The only differences were the color of the truck and the tire size when they were new. I think what I've done by sheer luck is discovered a flaw in extremely early 2002 Dodge 4.7 wiring harnesses. Both died the exact same way seemingly, and I haven't ever heard of this out of 4.7 Dodges at all.

 

[Fishstickz]

So best I can tell I've got it figured out. The 5v source wire comes from the PCM for both the cam and crank sensors, and goes through the sensors coming out of different pins. The wiring harnesses (both) have no continuity from the pin to the connection. The original up in the harness a short ways had been repaired, presumably because of this before. I haven't checked the grounding pins yet on the crankshaft connection to see if they're a complete connection from the PCM to the sensor.

Being as though both trucks were quad cab, built 9-2001, and had identical part numbers on the PCM, it stands to reason they were extremely close in sequence. The only differences were the color of the truck and the tire size when they were new. I think what I've done by sheer luck is discovered a flaw in extremely early 2002 Dodge 4.7 wiring harnesses. Both died the exact same way seemingly, and I haven't ever heard of this out of 4.7 Dodges at all.

I haven’t heard of anything either, but very strange you found two harnesses with the same issue. Blind luck I guess lol

Hopefully you can get that fixed and get back on the road


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[MrBman2000]

So update, got the service manual and away I went. We have 3v on the 5v circuits, and I've done a lot of testing, been at it since 9 this morning.

All the sensors are unplugged the manual shows on the 5v circuits, both primary and secondary, and there's been absolutely no change in that no matter what was done. I've checked every PCM ground from the connectors to various points and they're all good and check out just fine. I've tried a different battery, fuses, relays, and even checking voltage at different connectors on the 5v circuit.

It's at 3v out of 5v and refuses to do anything improvement related. Tried the other PCM I have and it too shows 3v, and retested all the tests I've done with it. It's got 3v, only 3v and it's adamant in that fact. I've checked the supply pins of 12v to the PCM and best I can tell I have 12v everywhere I'm supposed to coming into the PCM. The ASD also passes all the testing I've done.

I'm to the point I question both PCMs, the one I got from my friend's parts truck, the truck supposedly was an engine donor, makes me wonder if the reason it was junked wasn't because it was rusty but more of it did exactly what my truck did and they junked it over the truck's condition rather than hunt it down.

 

[Fishstickz]

So update, got the service manual and away I went. We have 3v on the 5v circuits, and I've done a lot of testing, been at it since 9 this morning.

All the sensors are unplugged the manual shows on the 5v circuits, both primary and secondary, and there's been absolutely no change in that no matter what was done. I've checked every PCM ground from the connectors to various points and they're all good and check out just fine. I've tried a different battery, fuses, relays, and even checking voltage at different connectors on the 5v circuit.

It's at 3v out of 5v and refuses to do anything improvement related. Tried the other PCM I have and it too shows 3v, and retested all the tests I've done with it. It's got 3v, only 3v and it's adamant in that fact. I've checked the supply pins of 12v to the PCM and best I can tell I have 12v everywhere I'm supposed to coming into the PCM. The ASD also passes all the testing I've done.

I'm to the point I question both PCMs, the one I got from my friend's parts truck, the truck supposedly was an engine donor, makes me wonder if the reason it was junked wasn't because it was rusty but more of it did exactly what my truck did and they junked it over the truck's condition rather than hunt it down.

There’s some possibility to that, but this is the first I’ve ever heard of a problem like this. I would imagine this is a rare occurrence, so you coming upon 2 PCMs with the same unheard-of issue AFTER coming upon 2 wire harness with the same unheard-of issue is (in my math) statistically impossible. Of course its technically possible, but if both PCMs have been bad it looks like you’ve got some bad luck with this truck lol

How many black cats have crossed the road in front of you recently lol


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[MrBman2000]

Well the original harness wasn't CONFIRMED to be a wiring issue, it had been half rewired with all one color wire though and had various crimps on it and was a visible disaster. The second harness I thought didn't have any power at the crankshaft sensor, but it does, the 3v of power I have everywhere else that 5v is supposed to be present.

In theory, and for my current assumption and well tested and resistance checked purposes, both harnesses are fine, albeit the one that was original to the truck in very poor shape. That means both PCMs are bad, from the same problem. The guy swore the donor for the junkyard PCM ran, but I'm doubtful. It's missing the engine though so who knows. I didn't give him but $20 for the PCM and I figure it's a good core if nothing else.

With that said, my luck isn't the greatest lately. I collect 2nd gen Explorers with the 5.0 V8, have three of em. I've hit 3 deer in 5 weeks in the one I use for a work car...

 

[Oliver Closehauf]

Sooo, you may want to make sure the battery in your multimeter is good. I've had issues where a low battery causes the voltage to read low.