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'04psthrottlejockey
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Discussion Starter #1
I have an '04 6.0 that shut off going down the road. Since I have had a no PCM communication, no crank with key, no fuel pump with key. I can crank the engine by jumping the solenoid and fuel pump works when jumping over the relay. I have had two different PCM's preprogrammed to my vin and just replaced the engine harness that goes to all sensors, FICM, and PCM. There were lots of bare and fused wires in the old harness. Not to mention my fan clutch harness got into the fan and destroyed it. I'm converting the fan to a '97 7.3 mechanical clutch for that reason. Any insight from anyone else would be immensely appreciated. Oh and I have been through every fuse and relay in the truck with a multimeter and all of them test good.
 

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Did you replace the overhead harness that goes to the starter and headlights? The one that is attached to the firewall and goes over the turbo. Does your pump turn on when the key is turned? That harness is connected through the trans harness to the pcm. If your pump does turn on with the key, there's a good chance that your over head harness is bad. I had a similar case. I have a FASS pump so that is separate. But I took the truck into the shop and was testing for a running issue and then all of a sudden truck wouldn't start, with the key on, I could manually jump it but had no communication. I was good from the pcm to the cjb and to the starter but nothing would go. Swapped pcm's and nothing changed. Jumped it and drove home. I was repeatedly blowing the dlc fuse.

Check for rodent damage on your pcm connector for the overhead harness and check for melted wires at the spot above the turbo in the plastic shield.

Hope this helps

you can text me at 217-766-9101 for more help

Jon
 

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'04psthrottlejockey
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21 Posts
Discussion Starter #3
I will definitely check that next. My Fass pump is relay' and triggered by the factory wiring and does not turn on with the key. When it shutdown though I had hot wired the pump and jumped the solenoid with the key on and no fire.
 

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'04psthrottlejockey
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Discussion Starter #4
Update: I have tested the cam bus wires at the DLC, PCM, and FICM and all have 120 ohms. Digging more into it I have a couple terminals at the PCM plug that are in question weather or not they should be going to ground because they are right now. When I know more I will post it up.
 

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'04psthrottlejockey
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Discussion Starter #5
Problem solved. After changing the engine harness and installing the mechanical fan clutch I failed to check the fuses agin after having everything apart. Changed the pcm power fuse and all is good.
 

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Yep that is the modern equivalent to forgetting to put the rotor back in after a full engine rebuild... Good on you for being persistent.
 

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'04psthrottlejockey
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Discussion Starter #7
Thanks rock doctor. It needed the engine harness since it had a bunch of bare wires and the fan clutch harness was trashed by the fan. But I'll never have to worry about that again thanks to bullet proof diesel and their mechanical clutch adapter.
 

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Did you had access to Powertran CAN at that time ?

2006 6.0: died while driving, now crank no start. No access to PCM to check for DTCs. Have "TBC failure" in the dash display.
 

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"resident smarty pants"
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4,067 Posts
The fan clutch short will blow fuse #22 which eliminates communication over the DLC AND it prevents the PCM from sending the ground signal. You have proven that the ground signal from the PCM is making it to the CJB.

Different situation for you, but I wish you well in your hunt. Maybe there is some experience here with your specific problem.

@jamiesaun is good at this stuff if he has time to read it all (previous troubleshooting from other forums). I have also sent him a PM.
 

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Master BS'er
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Okay, just quickly looked at one of those threads and there were no codes from the pcm, but were codes from other modules. Also the cluster reported a bus fault. The pcm and trans are probably on a separate bus and that bus is down. That's where we need to start. I don't suppose you have an oscilloscope do you?

I can't help ya until I get some schematics. I'll print em up when I get into work. I'll need the year and model.

What are the time zones like? He's probably half a day ahead of us isn't he? If any of that was in the other threads let me know.
 

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"resident smarty pants"
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Central European Standard time I am guessing (20 min from Heidelberg) from what he says on FTE.

I don't think that he has an oscilloscope, it is a 2005 tow truck (not sure the model) .... but he should be on and answer those questions!
 

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Thank you for your helpfulness. I am here in Germany and unfortunately I am many hours away from you.
Unfortunately I don't have an oscilloscope.
It is a 2005 6.0 F550 with an unusual doorsticker

 

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the motor crankes fast, but does not start.
Fuel pump does not run (works when directly powered).
No power on the inertia switch, green/yellow cable ok.
fuel pump relay in CJB does not switch, signal (negativ for spool) from PCM is present.

here you can see mit "no access to PCM"



please excuse my bad english, i have to work a lot with a translation tool.
 

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The instrument cluster display also shows "TBC failure". But the error is already longer. The engine ran with the message. The engine died while driving. The dying occurred twice, but the engine could be started again after a few minutes.

 

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"resident smarty pants"
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Hartwig -

Post the pictures of the engine harness (the one over the turbo that HydroTec asked you to post) here on this forum.

That harness, coupled with the PCM case seal, and the CJB wiring (starter relay), says there has been a lot of "hack" repairs or modifications.

IMO you need to plan on getting a new main engine harness, (and also IMO) it supports trying a known good PCM (which you have in your 2006 truck). The only risk is that you don't know how that truck is wired now and there may be a slim chance that a known good PCM could be damaged if the wiring was bad.
 

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Okay, just quickly looked at one of those threads and there were no codes from the pcm, but were codes from other modules. Also the cluster reported a bus fault. The pcm and trans are probably on a separate bus and that bus is down. That's where we need to start. I don't suppose you have an oscilloscope do you?

I can't help ya until I get some schematics. I'll print em up when I get into work. I'll need the year and model.

What are the time zones like? He's probably half a day ahead of us isn't he? If any of that was in the other threads let me know.
Watch the vid again -- pcm, instrument, abs, tbc, are on the main buss
The Trans controller is in the PCM, so that in general is working
He can communicate with the Trans controller, but the Powertrain controller is offline
Buss fault in the IC, I think is because the TBC is not working
 

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News!
manually controlled, the TBC module works, I'll give you a video later.
with unplugged C1381b i have access to the "Enhanced Powertrain CAN", the pre-glow lamp (CAN failure) disappears, the message "TBC fault" remains in the instrument cluster display

 
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