PCM Not Detected...Status Unknown

[Turbo Performance]

So basically I'm to the point in my swap that I'm wanting to fire the LLY engine. I had to build a harness to go between the engine and ECM. Everything is pinned out, powered, and grounded correctly to the best of my knowledge/ability. Hook up EFILive, click upload from PCM just to see what's on the ECM. It says PCM not detected, goes through 10 attempts before saying status unknown.

First thought is double check grounds but do any of the experts have any other places I should look? I bought the ECM used off here so I suppose there is a chance the ECM is bricked. I just wanted to make sure I checked all the easy stuff before sending it off to be checked. TIA.

 

[IdahoRob]

OBDII port not connected correctly or powered up will cause this. If in a standard truck, check the fuse for the power to the OBDII

 

[Turbo Performance]

OBDII port not connected correctly or powered up will cause this. If in a standard truck, check the fuse for the power to the OBDII

Thanks Rob. I know the OBDII is powering up as the V2 powers up on plug-in. I'll double check the data pin at the ECM. Anyone have any other suggestions?

 

[Turbo Performance]

Got it figured out. Blew a fuse somehow.

 

[JD Dave]

So will your V2 screen still light up with a blown fuse. I'm having a problem of not recognizing my PCM with the new LBZ ECM. My screen lights up so I thought it was fine.

 

[03spoolindmax]

I can't say this goes for our trucks but I've done some swaps on other cars and had communication issue.

I've seen where the data wire on the ALDL connector in the car is in a different spot. Swapped old wire to new pin on ALDL connector and it worked.

Can't same it's the same on our trucks though. Just thinking out loud

 

[Turbo Performance]

So will your V2 screen still light up with a blown fuse. I'm having a problem of not recognizing my PCM with the new LBZ ECM. My screen lights up so I thought it was fine.

Yes, at least in my case it did. Everything was normal except when it checked for PCM status. It would try I think 10 times before saying PCM undetected/Status unknown and ask you to turn off ignition. I believe the V2 draws power from the OBDII so the screen lighting up or not wouldn't necessarily be indicative of PCM state.

 

[JD Dave]

Yes, at least in my case it did. Everything was normal except when it checked for PCM status. It would try I think 10 times before saying PCM undetected/Status unknown and ask you to turn off ignition. I believe the V2 draws power from the OBDII so the screen lighting up or not wouldn't necessarily be indicative of PCM state.

Ok that's good to know. Thanks. The whole truck was rewired so it could be something more then that but I'm keeping my fingers crossed.