One SKIM key works, the other one doesn’t

[TJ Jim]

So I changed out the tumbler, actuator pin and the ignition switch. Now my old key sometimes works, and the second key always works. This has popped up several days after the tumbler and parts were changed. Changed out the parts because the accessory position was flaky. That fixed the flaky problem.
Why would the old key stop working and the second key work every time?

So far anyway.

 

[GATORB8]

Skim working or the key? The old key could be worn down just enough that the pins aren't clearing?

 

[TJ Jim]

I thought the gray part of the key held “nfc” to tell the skim it’s ok to start? So the pins in the tumbler are part of the skim workings?

 

[macleanflood]

I'd chalk it up to you touching something within 500 yards of a skim module that would cause it to spontaneously stop working.

Curious if you can monitor the behavior with a code reader or DRB and see what it sees.

-Mac

 

[GATORB8]

I thought the gray part of the key held “nfc” to tell the skim it’s ok to start? So the pins in the tumbler are part of the skim workings?

No, I was confirming it was a skim issue, not a tumbler issue (like the key wasn't rotating the cylinder).

 

[TJ Jim]

No, I was confirming it was a skim issue, not a tumbler issue (like the key wasn't rotating the cylinder).

No the key turns fine. It starts, the key slash circle on the dash flashes and the engine dies. My wife’s key starts it normally. It’s been barely used, still has the shiny on it not worn down to the brass like my old key.

 

[TJ Jim]

I'd chalk it up to you touching something within 500 yards of a skim module that would cause it to spontaneously stop working.

Curious if you can monitor the behavior with a code reader or DRB and see what it sees.

-Mac

You lost me. I left home and stopped at the liquor store ten miles away. It wouldn’t start at the liquor store. Used the wife’s key and she started right up. Drove to the feed store and tried my key again. No start. Put the wife’s key in and it worked fine again.
I’ll have to dig through my reader and see if it tells anything.

 

[TJ Jim]

Just went out there and held the wife’s key next to the ignition and used my key to turn it over. She started right up.
Either the skim module is going bad or my key is going bad. I was just understanding the key was nothing but a coil that when excited by the skim it would signal back and say it’s okay to start.

I gotta relook at my assembly job and see if I disturbed the ring that reads the key. Hoping there’s an “nfc” expert on here.

 

[macleanflood]

You could take it to a hardware store that "duplicates" keys and see if their reader will read it enough to copy the code.

Wonder if there's a smart phone app that would read it...

-Mac

 

[CharlesHS]

My key was exhibiting the exact same problem approximately a year ago.
There were times the engine would start and run; after several minutes it would die.
Other times the engine would start and run fine.
After testing numerous electrical connections and reading voltages and resistance on relays; I noticed the amber SKIM key symbol was flashing when the engine died.
To test a theory I brought a spare key with me during a drive when the engine died, tried cranking the engine on and off for several minutes and it wouldn't start. Swapped to the spare key and the engine started immediately and ran fine; switched the engine off and tried the original key and the engine would start.
Since resolving that problem I have labeled the problem key "Bad Chip" kept since the key cuts are in very good condition.

NOTE: There was a series of SKIM keys that were produced with bad chips; I believe it was the C series.
A friend of mine worked at the Jeep dealerships for many years found this out the hard way while programming keys for my Jeep.
The dealership returned ALL keys of that series when he brought it to their attention that the keys were produced with faulty chips.

 

[TJ Jim]

My key was exhibiting the exact same problem approximately a year ago.
There were times the engine would start and run; after several minutes it would die.
Other times the engine would start and run fine.
After testing numerous electrical connections and reading voltages and resistance on relays; I noticed the amber SKIM key symbol was flashing when the engine died.
To test a theory I brought a spare key with me during a drive when the engine died, tried cranking the engine on and off for several minutes and it wouldn't start. Swapped to the spare key and the engine started immediately and ran fine; switched the engine off and tried the original key and the engine would start.
Since resolving that problem I have labeled the problem key "Bad Chip" kept since the key cuts are in very good condition.

NOTE: There was a series of SKIM keys that were produced with bad chips; I believe it was the C series.
A friend of mine worked at the Jeep dealerships for many years found this out the hard way while programming keys for my Jeep.
The dealership returned ALL keys of that series when he brought it to their attention that the keys were produced with faulty chips.

That’s really interesting and good to know! I put my bad key in the ignition, and pressed the wife’s good key against the side close by. It started right up, and continued starting even with the good key away. Gonna try it again this morning and see if my bad key works today.
After googling a bit it looks like it’s not an “nfc” setup, but like you say it has a chip in it.

Bottom line is maybe the key chip went bad in the non working key. Gonna try to get a key made I think and see what happens. Was planning to send the computer to @Wranglerfix and having skim deleted but I’ll try the key first.

What bugs me is all the new key parts I put in and then the problem came up?

 

[Wranglerfix]

If you have one good key you can take the chip out and tape it near the skim module. You can then start with a metal key. It will make the jeep easier to steal but so will removing skim. The downside to skim removal is the security light will always be on but not cause any drivability issues.

 

[TJ Jim]

If you have one good key you can take the chip out and tape it near the skim module. You can then start with a metal key. It will make the jeep easier to steal but so will removing skim. The downside to skim removal is the security light will always be on but not cause any drivability issues.

Calling around now trying to find someone that can program a key. Only one locksmith in the area and having trouble catching him. Called the local Jeep dealer and they are just so confused.
I think the winter storm warning is driving folks nuts around here.

 

[CharlesHS]

When I first had the SKIM module installed and the ECU programmed by my Jeep dealership friend; the bad chipped SKIM keys were all that was available.
We went to Ace TrueValue and had them clone another key so that I would have two working keys until the C series SKIM keys became readily available.

 

[TJ Jim]

Well, I just got a new key programmed and cut for $100. The new key works. The key guy said they work on “RFID” so I’m gonna study how that works. He said NO WAY is the key bad that’s it’s probably the skim or the computer. Being hard headed as I am how can one key work and the other key be intermittent?

For now even the old key is working just fine

 

[TJ Jim]

Tag=key
Reader=skim
Antenna=ring around the key tumbler

RFID, or Radio Frequency Identification, works by using electromagnetic fields to automatically identify and track tags attached to objects. An RFID system consists of a tag, a reader, and an antenna; when the tag is activated by the reader's radio waves, it transmits data back to the reader, allowing for identification and tracking of the item.
https://duckduckgo.com/?q=how+does+rfid+work&t=iphone&ia=web&assist=true