Hey this is my first post but I've gotten a lot of help from reading the forms on here. I have done a complete cab swap on my late 99 rebuilt the motor completely heads whole 9 took my entire harness out of my 99 and placed it in a 04 cab. I can't get the thing to start. I have good cps signal tested the idm and pcm both are good "will make my 01 550 run" but even with the pcm and idm out of my other truck I can't get any voltage at the center pin on either valve cover gasket. I've check power and ground at my idm and pcm both are good. So my question is what will not make the idm power up completely. Will do a buzz test fine and I have no idm codes.

 

If it completes a buzz test, the IDM is most likely powering the injectors properly. Whether it's actually being commanded to fire the injectors while cranking may be another story. Set up your scan tool to monitor ICP, IPR DC, RPM, vehicle voltage and injector pulse width with cranking. For the PCM to send a fuel delivery command signal to the IDM, it needs to see minimum 100 RPM, 500 PSI ICP, and 7.5 volts. (The IDM itself may require as much as 10.5 volts to operate properly, though.)

 

My first thought, fuel bowl heater shorted out!

 

PCM won't wake up to do a Buzz if the fuel bowl heater is shorted.

This has a CPS smell to it. Do as Pikachu suggests, you'll find your answer. This is all documented in the last link in my signature as well.

 

After two weeks of chasing wiring and not thinking it would be something simple I pulled the valve covers to double check my injector o-ring. Turns out that my scanner was lying to me because when I rebuilt the motor I missed the rear hpo rail drain screw. So I rushed and it bit me. I rebuilt the motor because of cracked piston cylinder 2 and it had 400k original miles. But she lives. Thank you guys so much for responding I just hope someone learns from my mistake and doesn't trust a snap on scan tool to read icp and not to rush motor work.

 

Ah... I would check your ICP connection. If the ICP is disconnected, the ICP reading on the PCM will go to default values. I'm sure your Snap-On tool is OK.

 

My pig tail was shorted replaced and now it's reading proper 500-700 idle at 42 Deg getting cold up here

 

I'm kind of surprised it didn't set a code and ignore the sensor reading. That's what's supposed to happen in a situation like that.