3rd gen voltage problem

Jedrattle

Active member
Joined
Jan 28, 2022
Member Number
4751
Messages
30
The 5.9 blew up last year and I found a take out to replace with. I finally got around to putting it in over the weekend. I tried to start it up but no go. I had no gauges at first. Found some disconnected grounds and that fixed the guages. Still no fire. Figured out I’m not getting fuel past the cp3. The dash has the engine check light on. The codes are for high battery temp, high intake temp, map sensor and low pedal voltage. I discovered my volt meter is going to 14 and then dropping to zero like 3 seconds after the key is on. This seems like what is causing it not to start. I’m at a complete loss on this one. My internet search is showing a running truck problem. My batteries were fully charged and clean connections.

Edit
The voltage is at 12.8-13ish not 14
 
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It shouldn’t read 14v unless you have a charger hooked up. Does the volt drops at battery too when key turned to ON with DMM?

Did you mistakenly hooked up heater grid cables to ground instead of heater grid’s studs?
 
TrailTamer said:
It shouldn’t read 14v unless you have a charger hooked up. Does the volt drops at battery too when key turned to ON with DMM?

Did you mistakenly hooked up heater grid cables to ground instead of heater grid’s studs?
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You’re right. 12.8-13ish on voltage.
No I did not. The grid heater is hooked up correctly.

I went through and doubled check the wiring connections. I got a code reader and cleared all the codes. Took the battery cables and cleaned them and made sure they’re tight. Batteries are at 12.5 volts. The batteries drop .02 volts with the key on. Now the voltage isn’t dropping. Still no start and all the codes came back.
 
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The ECM is extremely sensitive to voltage. I'm betting a fault there.

There's a few reputable companies that 'rebuild' them. I'd send it off and have it tested.
 
TRINDU said:
The ECM is extremely sensitive to voltage. I'm betting a fault there.

There's a few reputable companies that 'rebuild' them. I'd send it off and have it tested.
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I hope like hell that’s not the problem. The prices for the computer is almost as much as my mortgage and work has been really slow for a long time. 🤦🏼
Whose “reputable”?
 
Don't the third gen have problems with the fuse box itself? Instead of having a simple circuit with a fuse, the 3rd gen have a circuit board with fuses. TIPEM I think it is called.
 
JDNobodi said:
Don't the third gen have problems with the fuse box itself? Instead of having a simple circuit with a fuse, the 3rd gen have a circuit board with fuses. TIPEM I think it is called.
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That’s first I’ve heard of that. I won’t rule it out
 
TRINDU said:
TIPM, totally integrated power module.

You should be able to test the fuse ports for power though.
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Yeah I just did a search. I remember watching a video where somebody was moving the TIPM and it was affecting how the truck ran or it shut off. It has been awhile.
 
The ECM is the cummins computer on the block , the PCM is the mopar computer on the firewall. I am assuming that long as the ECM has power, grounds, and sensor inputs that it will run with or without the PCM. The PCM basically just runs the 48re, cluster, and grid heater. That is how the vp44 trucks are, and I am pretty sure the 5.9 commonrail is the same deal.

So you need to check that your ECM on the block is getting the power and grounds it needs to power up. Then check to make sure you have no open circuits between the sensors and the ECM.

If your ECM is fragged, which doesnt seem likely I would send it out to be repaired. I have been watching Keyworks ECU's videos on the youtube , went down a ECM repair video rabbit hole, anyhow the quality of work from a repair shop is going to be leaps and bounds above an unknown "reman" unit.

Link to keyworks shop if the one posted above doesn't work out. Keyworks Mail-in Key and ECU Repair Services
 
Had to take a break from this for a little bit..

Thanks guys. This has been a ridiculous amount of work and frustration. I need to double check the ground that goes to the ecm mounting pad on the side of the block. A friend of mine thinks that something isn’t communicating with something. He thinks there’s a 5 volt feed connection not making contact which is causing the codes. A guy at work found a video, where a guy was having similar problems. In the video, the 3rd shop finally found the problem. Two of the female pins in one of the big connections had backed out. Of course then, those wires weren’t making connection and therefore throwing codes, etc..
 
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