crank/no start, no comm with scan tool.

ShaferDiesel

ShaferDiesel

Way To Small!
Joined
Nov 3, 2012
Messages
159
Background...
early 03 6.0. Truck died and got towed in to me. it was obvious HGs were blown, 1 qt black coolant left and water spots all around the resivoir. I put scan tool on and found FICM voltage was very slow to build, se we did HG, studs, egr delete, oil coooler, and I rebuilt the ficm. Truck fired right up and ran great, except for a very intermittant cut out twice. I drove it for a day and decided it would be fine. Owner came and truck would not start.

so now to the current part of the story...
I connected my laptop to check ICP and FICM voltage, and it would not connect. I have a cheap handheld that I tried as well without luck. I checked PCM fuses, relay, pulled connector at ecm and checked for grounds and power, all checks out good.

Next I ohmed the can lines at the DLC, I have 120 ohms, so I disconnected the PCM body connector and I have infinite ohms, so instrument cluster is not connected, and also I have no odo display. I pulled it an swapped another 03 cluster in, and now my scantool works, so I don't bother checking ohms again.

No codes were present, but I'm not gettting any RPM reported by the scantool or the tach, so I checked resistance at the PCM connector for the CKP and have an open circuit, but the CKP itself ohms out okay. I replace the engine wire harness and now we have a crank signal and CMP/CKP sync reported on the scantool and the tach but still no start.

Now when I crank the signals go dead on the scantool and come back after not cranking for a few seconds, so I cant see rpm, ICP, etc except for the first 1/2 second of cranking. I disconnect my scantool and reconnect and cannot get it to reconnect again. DLC still ohms at 121 ohms, so new instrument cluster still is not online.

Now this may sound like batteries but they are new, I have a a charger on it full time, and cranking voltage is 11.2. I rechecked PCM power and grounds and they are good even while cranking.

So next I sweeped PCM to a known good one off another 03 and still have the same results, even with the engine wire harness disconnected to eliminate a short it any of the 5v vref sensor of ficm. WTH now???

I need help, I need to get payed for this soon!
 
I know I may get blasted for this. But have you verified all the grounds are hooked up and clean. Almost sounds like a loose connection.
 
Bad moose, that's kinda what I'm thinking. I have cleaned all connectors on the driver wheel well. Now i'm under the dash. I've been looking for a diagram of the grounds on this truck, I thought I had one somewhere but I guess not.

Matty, they are all good, and it does buzz the injectors at key-on, and the fuel pump runs. It takes 20 seconds for the odo to light up and the tach to start responding, and I don't think that is normal, I just got two more 6.0s in this morning so I'll do some comparing, I had another one here yesterday but as soon as it got it's batteries hooked back up it had to leave so I didn't get to play with it at all. I think we're on HG/stud/oil cooler job 3 already this week lol.
 
Pull the ficm and look CLOSELY at the pins. Make sure none of the ficm wires in the harness are pulled back from the plug. Push every wire in the harness into the ficm plug. I have seen this before and it was a ***** to figure out. Turn the key on and all kinds of weird **** would happen. 3 years later the truck runs fine just from pushing ficm wires into harness.
 
Check for a ground at the right rear facing the truck. I want to say on the intake or in that area. I almost forget to hook up mine. While hooking it up found the wires breaking at the crimp.
 
I am fighting the same issue but I cant even get it to crank over. December build '03. The guy I had looking at it swears up and down it's a ground issue and even went as far as replacing the entire fuse block in the cab. It didn't change a thing, so off she goes to the dealership. FML. If you figure it out I'd love to hear what it is.
 
matty169 said:
Pull the ficm and look CLOSELY at the pins. Make sure none of the ficm wires in the harness are pulled back from the plug. Push every wire in the harness into the ficm plug. I have seen this before and it was a ***** to figure out. Turn the key on and all kinds of weird **** would happen. 3 years later the truck runs fine just from pushing ficm wires into harness.
Click to expand...

What Matty said. I had one run me in circles.
 
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