2thousand5.4

Hey guys. My mom's 04 expy is throwing a B1681 code (pats error) and I can't figure out the fix. I'm decent with electrical stuff and can't find any shorts. The truck will crank fine but obviously won't start. It used to just be an intermentant issue but now it won't go away. The first time it happened I disconnected the Xpress box to disable the remote start I put in a while back and it fixed the issue for a while. Then it would do it every now and then but always "fix" it's self within 10 minutes. Well it has been 2 days now and it's still not working. I went ahead and took out the whole Xpress wiring harness and it didn't help. Do yall have any other suggestions? I had mpt turn my PATs system off a while back on my 2000 F150 (needed a new key and it was cheaper to have them update my tune to bypass PATs then program a new key, plus it made the remote start a simpler install). But, to tune a second vehicle I have to send my programmer to Sct to have it unlocked then buy another tune from Mpt so it will end up being like $200. Always an option to do that but I would rather fix the issue.

BadFish523

Have you tried multiple keys? Maybe the chip in the key is bad?

2thousand5.4

Yep tried both keys as well as keeping the battery disconnected over night.

2thousand5.4

It's wierd because the anti theft light isn't flashing any codes. I'm just pulling that one code by hooking my 3015 up to it. I don't see any problems with the wiring harness so maybe the ignition immobilizer/key transponder is bad? I hate to just throw parts at something but that's only $10 so maybe its worth a shot. Originally I thought it was the fuel pump relay (r303) inside the fuse box so I took that hole thing out and the relay wasn't burnt up so I know that's not the issue either. I'm not a 100% sure but the 4.6 doesn't have the FPDM right? I know more about tenth gens.

BadFish523

I might be wrong but I think all 11th gens have a fpdm. They do cause weird issues and there's always the good old "doesn't cost anything to visually check it out"

2thousand5.4

I'll check it out tommorow after work. Ended up finding a key immobilizer for $7 so I decided to grab that to see if it helps.

2thousand5.4

I'm tired of ****ing with this thing I'm ready to load it with tannerite and blow it to hell. I have tried everything, new transceiver, new connections, traced all the wiring, still nothing. Any last tips before we dump 250 into getting this hell of system tuned out

BadFish523

It could just be an error in the computer and getting it flashed at a dealer might be the only way to fix it.

BadFish523

Did the expy have a FPDM?

2thousand5.4

I wonder if I put a generic sct tune on it if it will help
Nope looks like the 4.6 didnt get it in the 04 model