04 RAM 5.7 REBUILD

[Devin A Mccollum]

Hi everyone! My name is Devin and I have a 2004 ram 5.7. While I was riding down the road last October my main bearings went out and the crank seized on me. Completely shredded two piston heads, rods, everything, (got pictures if anyone wants to see)
So I took the engine out, had the block bored out .030 and replaced cylinder heads and did an entire rebuild. I replaced both cam and crank sensors, all mechanical components and got it all back together. Now when I go to start the truck it turns but won’t fire, I’ve tried resetting computer using battery cables, checked voltage at sensors. I have pressure in my fuel rail. I checked for voltage at the coil packs and I have voltage at the pack during crank(12v) however when I ground the connector to itself I lose voltage. I see voltage when I ground to battery off connector. I was told the crank sensor acts as the ground for the coil packs however all is testing good. Any idea as to why my truck isn’t letting voltage go through the packs?

 

[madtrucker2016]

crank position sensor might be bad check with meter

 

[Fast69Mopar]

Just out of curiosity, did you re-use the original crankshaft or did you install a different crankshaft?

My reason for asking is because I have seen too many people install a damn crankshaft without the crank sensor tone wheel bolted to the new crank.

 

[Devin A Mccollum]

I have checked the crank sensor and it checks good, I also installed a new crank. I did remember the reluctor ring!

 

[Fast69Mopar]

Okay, good for you man. I have seen way too many forget.

Next step...when you turn the ignition key on (not attempting to start the engine) verify that the ASD Relay is being energized for a few seconds. Take the cover off of the ASD Relay and watch the relay.

Next, Do you have a scan tool or access to a scan tool? You need to be able to look at the data stream and see the cam and crank sensors and see of they are counting.

If you do not have a scan tool, you can back-probe the crank sensor connector and watch the voltage with your DVOM and see if the crank sensor is recognizing the tone wheel.

 

[Devin A Mccollum]

I’ve tried checking the reference voltage off of the crank sensor and I’m getting about 2V or so while my buddy tries to crank. My ASD relay is being energized, I swear my truck tried to start when I was checking the voltage but my buddy turned it off when it was about to fire.

 

[Fast69Mopar]

Okay. Have you removed an ignition coil from the head, plugged in the connector to the coil, stick a spark plug in the coil and ground the tip of the spark plug to see if the coil is firing while cranking? Do we know that we are missing ignition spark in this equation? I think that is the first thing we need to verify. If we find that the coils are not being energized to light off the spark plugs then we can decide which way to go with the diagnostics.

 

[Devin A Mccollum]

Yes I’ve tried that exact method and I’ve stuck my test light in the coil and tried to crank. Both yield no spark, connector is getting voltage. It’s as if the computer isn’t getting a good ground signal

 

[Devin A Mccollum]

Even bought a brand new coil to test. Same outcome as the old, couldn’t imagine all 8 going out at once.

 

[Fast69Mopar]

Yeah I highly doubt all 8 ignition coils failed at once. Does your ASD Relay stay energized while cranking? When you have the key on and disconnect the crank sensor, do you have your 5 volt supply on one pin and ground on one of the other pins? I read your other post that said you saw 2 volts. Was that voltage being measured while your friend was cranking the motor? Was the voltage fluctuating like it was reading the square wave of the tone wheel? If you dont have 5 volts with the crank sensor connector unplugged then we need to find out where the voltage drop is coming from. The 5 volt supply coming from the PCM can be very picky. If you have another sensor on the engine that is shorted internally or has failed all together then it can pull the 5 volt supply down and keep the engine from starting. If for some reason you do not have 5 volts at the crank sensor while the connector is unplugged, start disconnecting the other 5 volt sensors to see if the voltage returns to the crank sensor. There are several engine sensors that run off of the 5 volt supply from the PCM. The one that I always remember off hand that kept a customers truck from starting was the A/C Low Pressure Switch. The switch had failed and was pulling down the 5 volt supply and keeping the engine from starting. The Throttle Position Sensor, MAP Sensor, Intake Air Temp Sensor and Oil Pressure Sending Unit are all on the 5 volt supply. Disconnect each one and see if your 5 volts comes back to the crank sensor.

 

[LoneWolf3574]

Dumb question, are all your engine grounds connected? There's one that goes to the firewall from the RH head that is easy to miss, I found mine broken and my ghost electrical issues went away (random misfires, momentary oil pressure drops, etc).

 

[Devin A Mccollum]

I will check the ASD relay again tonight, I am getting 5V at my crank sensor now! Id also like to check my other connectors so I will. And I agree, as soon as I checked a couple coils, I was like “ no way all these are bad” I’ve never seen that. It’s gotta be something stupid I’m missing. Hoping it’s not the computer

 

[Devin A Mccollum]

Yes, all my engine grounds are good. I have the right well ground going to to heads over the bell housing. I have straps off the front of the heads that are damaged however they were like that before. I’ve also got good battery to block to frame grounds.

 

[buddy guy]

you sound like your pretty busy at the moment, but....hell yeah we want pictures!!! the motorcycle forum I frequent, members and mods put up a "this thread is useless without pictures" emoji string frequently

 

[Devin A Mccollum]

Hahaha I will upload some photos of before the rebuild and where we are at currently.

I checked my ASD relay using this step by step

https://www.ifixit.com/Answers/View/252231/What+and+where+is+the+ASD+relay

And my resistance reading is a little high. It says I should be around 70-80 and I’m reading about 92 ohms across a set of terminals. The relay energizes properly, iM curious of the high resistance will keep it from working properly.

 

[Fast69Mopar]

If the relay that is currently in the ASD slot is staying energized while cranking then I would suspect it is still working.

My next suggestion would be to pull out another relay from the TIPM and take the same measurements and see how close they are. If you have a large difference then take the relay with the least amount of resistance and plug it in the ASD Relay slot and retest for spark while cranking.

Also, if you can get your hands on a decent scan tool I would recommend it. We need to see the cam crank sync and verify that the PCM is seeing the crank sensor is counting teeth on the tone wheel. That would definitely help us with which direction to go next.

 

[Devin A Mccollum]

Alright, so I just rechecked my crank sensor connector while disconnected and with the key on (no crank) and I’m not getting a 5V I’m not getting anything. I do when I crank however. So I’m going to check all my sensors right now.

 

[Devin A Mccollum]

I’m definitely gonna try and grab a scanner.scratch that I actually have 6V under those conditions. I had a bad ground (shrug)

 

[Devin A Mccollum]

Does anybody have any experience with junkyard PCMs, I’ve got a local shop that has one for my truck for $99 as opposed to ordering one for much much more. Thinking I’ll give it a shot for fun and hope it works.

 

[HemiLonestar]

Does anybody have any experience with junkyard PCMs, I’ve got a local shop that has one for my truck for $99 as opposed to ordering one for much much more. Thinking I’ll give it a shot for fun and hope it works.

Is it the same part number?