Sounds to me like the SKIM system. (Sentry Key Immobilizer) There is an RF chip in your key and an RF module in your steering column. The module can tell when your key is present. The skim module operates independently from the PCM. When your mech changed the PCM did he also change the SKIM module? The two modules need to be synced...and then you need a new key synced to match the new SKIM module.
I detached my SKIM module (under the steering wheel cover, by your knees) by accident one time not knowing what it would do. I ended up with a new SKIM module and a new Key...just under 500 bucks later and it started right up.
Side note, if you unplug your SKIM module with your truck running it will become obsolete and you will not need a chipped key to start your truck anymore...But, if you disconnect your battery while the module is unplugged you will again need the SKIM key to start the truck.
Hope this helps

 

Thank you so much for the reply! I am not sure if he replaced the skim. All that he has told me is that he has replaced 2 other pcm's. I would not have replaced the second pcm, without replacing something else, in the name of progressive troubleshooting. I went by today to talk with him, and he was not there. He did have the steering column torn apart. He said the new pcm should be in soon and she will try something else. I would assume that he is replacing the skim too. If the skim was bad, would that cause the pcm's to go bad?

also, i had this taken to a locksmith who had a tool to reprogram keys for cars. would he have been able to reset the skim, or is it a physical part that needs to be replaced? was it $500 for the skim mod? he quoted me $728 for the original repair, but i am sure it will be more than that, as he is also pulling his hair out at this point.

 

I don't think the PCMs are getting fried. I think they're "locked" because a specific order of operations is not being followed for CAB (ABS) module replacement. I don't have a factory service manual handy but it should delineate the correct procedure.

 

In my '04 service manual it say that if you are replacing the ABS Controller (CAB) with a new unit it has to be programmed with a DRB III scan tool. Most repair shops do not have this tool because of the expense, but I would think all dealers would. I don't see how the PCM's could be frying because of this replacement. Like Kolak said, they may just be locked because the new unit was not programmed with a DRB III scan tool.

How is the mechanic determining that the PCM's are fried?

When you say it would not start after putting the original CAB back in, do you mean it would not turn over, or did it start then die.

Have you tried to pull any codes using the key on/off trick. Without starting the Jeep, turn key on/off/on/off/on, and if there are any codes stored they should show up in the odometer area.

 

Thanks for the reply! He just said that putting an programmed CAB would fry them. I was doubtful that they have actually fired, as i did not smell anything "frying". Fried electronics of any type have a very distinct smell! After the swap the car would turn over, but since the anti-theft system was activated it would not start, there was no fuel going to the lines, and the dash gauges would not work. The only thing that was working on the dash was the anti-theft light. I was unable to get any codes. Another question, If my pcm is locked, what needs to be done to unlock it?

 

When I replaced my CAB, the amber ABS warning light came on in the dash. I drove it to the dealer, who reprogrammed the 'brain' (two microprocessors in the CAB unit, itself). (There was no issue with the vehicle starting or running.) The only data that needed to be 'inputted' was the tire size, so as to count the correct number of wheel revolutions. Once done, the warning light turned off.

Not sure where you are getting your info as to the CAB being VIN specific. For both my 99 and 04 WJs, there is only one CAB available for each model year. Nothing to do with VINs. The FSM states that the CAB operates the ABS system 'Independent from all other vehicle electronics'. So, according to that, whoever says that your PCMs were fried and subsequently replaced them, is putting money in their pocket. The only step in the R&R of note, is to disconnect the battery prior to proceeding. When I replaced my CAB, I don't even recall disconnecting the battery. Power to the CAB is a function of the ignition switch 'RUN' position.

 

I was told by the lock smith who was reprogramming the keys that that information was stored in the CAB, and communicates with the PCM. How were you able to drive yours after the swap, lol. My jeep activated the antitheft system. I also tried the key fob reset trick with no luck.

 

The ONLY info the CAB stores is tire size and pinion factor. Nothing else not even the VIN. Worst case this would make your speedo read too fast or too slow.

Keys are stored in the SKIM.

This issue to me seems like another 4.0L engine with a crapped out crankshaft position sensor.

 

The ONLY info the CAB stores is tire size and pinion factor. Nothing else not even the VIN. Worst case this would make your speedo read too fast or too slow.

Keys are stored in the SKIM.

This issue to me seems like another 4.0L engine with a crapped out crankshaft position sensor.

If it were the crankshaft position sensor were bad i should still get fuel to the line correct, or at least pop some codes? And the last component swapped out was the CAB, then the anti-theft system was triggered. does anyone know where is can get a free FSM?

 

Just for the heck of it, can you remove the large multi pin connector (on the back of the CAB) that plugs onto the anti lock system? If so, check to make sure that no pins were bent out of position, or shorted to adjacent pins. The ABS is connected to the PCI communications buss. I'm not sure what a 'short' would cause the entire buss, but it's free and takes 5 minutes to perform.

 

any update?