The PATS or anti theft is not able to shut down a running engine, so I doubt that's it. If you key on and the PCM doesn't "boot up", you'll get a flashing anti theft, so I'm with Mark on this one. Check the power supply to PCM as well as PCM relay. PCM relay is easy, just swap it around with one of the other matching relays in the fuse box and see if it persists.

 

Silly Wild A$$ Guess

They may have damaged a wire when swapping engines. Or damaged the EEC power relay. Or it may really be a coincidence.

One way is to connect a scan tool to the OBDII port. If the tool loses connection right when the engine dies it would confirm that the PCM is turning off and shutting off the engine.

That's a big assumption. If the PCM is losing power at times it's going to work fine when the power is present. All you did was confirm that things are working when nothing is wrong. Test it when the engine won't run.

 

Good ideas. I did have my scangauge II hooked up while driving around and didn't notice anything off. I do not recall if it shut down- I don't think so, because all the other things on the truck were on and working.

I'll need to check on this.

I spoke with the shop and they have a dodge that's been doing the same thing. Been there for weeks. Very intermittent. Finally traced it to a bad PCM.
I hope that is not the case with mine... If that is the case, what is the recommended source for a new one- trying not to pay stealership pricing...

 

I'd even go so far as to probe the supply voltage to the PCM on the connector to make sure it's getting constant power even when the engine shuts down. Would hate to replace a PCM then the problem persists.....

 

I've relayed all of the info provided to the shop. They've had it for a week and have yet to be able to reproduce the issue. Must be me... LOL

I'll post up the resolution when it's all done.

 

Unfortunately, that's not you - it's "Murphy"

Hope they figure it out soon.

 

You mean we’re helping out the shop your gonna pay?

 

I always thought that it was
Scientific Wild Ass Guess??

 

It can be, but only when it's a better guess that what mine was.

 

If it gets his vehicle back sooner then think of it as helping the poster, not the shop.

 

Updates:

I only had the truck at the shop because it was still very cold out and I did not have the room to pull an engine and install the other, AND I don't have a lift which, as you know makes it that much harder.

Anyway, the shop has had the truck for a while and decided to pull the cluster as it was apparently showing all of the digital odometers numbers as lines and not numbers. AND the security light was flashing. The truck will not start now at all.

The shop brought in a guy who rebuilds the clusters and he said I need a new one. The shop claims that this may be 80% of the problem, but that as it sits, it will not start at all.

The owner said he could source me a cluster at his cost $595! I am thinking I need to have the truck towed back home so I can fool with it myself.
I'm very frustrated with this whole situation. I'm already pretty deep into this mess with the new engine and the install. Ready to set it on fire and push it down a hill

I am not sure what I should do at this point. I am not sure the cluster is the issue (neither is the shop for that matter). I could buy a used cluster off of ebay or a junk yard but I've NEVER had issues with a cluster. How is this even an issue?

I am hopeful you guys will chime in and help me out here.

 

Ok. So, I picked up the truck last night on a flat bed and it's now home. I did see some new issues...

1. The shop had pulled the dash as the theft light was flashing rapidly and the odometer looked like this (---------) instead of (114567). The shop claimed that as long as the (---) lines were displayed the truck would not even start.

2. They did state, however, that if the (114567) numbers appeared in the odometer screen that then the truck would start. They claim that the instrument cluster should be changed.... REALLY???? I don't think that is the solution.

3. After re-installing the dash they gave it power and attempted to start the truck. The relay under the hood clicked like mad. (I have never seen this happen on this truck. EVER) I think that they even swapped in a new relay to test it. Same issue.

4. I looked at some youtube video's with this similar issue and it appears that the PATS system has come alive and is disabling the truck. Essentially, cutting the fuel pump.

5. As an aside, on the way home from the shop, the car I was driving also had a failure- serpentine belt was destroyed- First time I've had to call AAA twice within 30 minutes for two different tows!!! Not my week!!!

Anyway, at this time, I am still a little baffled. I still only have the one key (the only one I've ever had and used for 11 years with no issues). The dealer claims that the key is $27 and the programming $60 AND that they need the truck there to program the new key. However, after checking the videos, it appears that the key is not always the solution.

Is there a way to simply disable the PATS so that I don't have to fool with it? Or, in the alternative, what are some of my options for a fix... I'm into this truck neck deep and have to fix it. Sooner is better than later...

Thanks to all who have posted thus far. It is appreciated. Maybe this thread will help others with the same or similar issue...

 

First thing I'd check would be if the PCM is getting good power. ----- in the odometer doesn't mean the cluster is gone, it means there's a communication problem. I think if the battery has been disconnected, the PCM and cluster has to communicate for the odometer to display correctly. Blinking anti theft is a strong indication that there's no communication with the PCM, to "seal the deal" you could try to connect a OBD2 scanner and see if it can connect. If there's no communication on the OBD port for a scantool, the PCM is not powered up. The first stop is to check the PCM relay, it's in the relay box under the hood. Swap it with another relay, there's several identical ones in the same box. If it still doesn't work, then you need to measure the 12V supply and GND wires at the PCM connector to ensure it's getting power.

 

No but I bet there are a lot of car thieves that wish there was.

 

Hey guys. I have a 98 Lincoln Navigator 5.4. I am having almost the same issue. I just changed the intake gaskets and almost every sensor on the engine. It does the same thing, where it will run fine for a while and out of nowhere it will stall out while I'm driving or when I am stopped at a light. It normally would start right back up and go. However occasionally after it stalls it will not start unless I cycle the key. Today it stalled and would start and immediately stall. Then it would start and run until I try to put it in gear and drive. I'm wondering if someone would have any input