Spontaneous de-programming of keyless entry remote?

anthrax323 · Feb 18, 2011

Hey guys, I've got a 2001 XJ with keyless entry (but not SentryKey... just the key fob) and last week it spontaneously stopped working. Checked the passenger side fuse panel and found that fuse #9 (IIRC), which was responsible for the overhead console and a couple other things, was in good shape. Everything else on the vehicle works, including the power locks.

I took my remote by an Advance Auto Parts and used their little display unit of some sort to confirm that it is still putting out an RF signal. Given the lag/latency in responses from the keyless entry system in the past, I thought it might just be on the fritz, so I disconnected my battery for ~10 minutes and reconnected it... Still no dice.

The events that transpired leading up to its failure were as follow:

Keyless entry stopped working, so I replaced my remote battery and all was well.
Less than a week later, it stopped working again. Replaced battery again and still no dice.
After about a week now of it not working, I reset the ECU (disconnected the battery) last night as a last-ditch effort. Still no dice.

Before I go pay $50+ to have someone reprogram it (seeing as you apparently need some special scanner to do it), are there any other basic diagnostics I can perform on the receiver in the dome light assembly, or is it safe to assume that the key fob just "lost" its programming? The dealership suggested this is a possibility, but barring some kind of accidental reset of the key fob on my part, I think it's a stupid idea.

Any thoughts?

robsjeepxj · Feb 18, 2011

Maybe the fob is just going bad it is ten years old right? I know they come with 2 from the factory, do you have the other one still? Maybe you could try that one instead? Also I thought maybe the battery might just have been put in backwards but I'm not sure if it would work at all then. Good luck with it.

anthrax323 · Feb 18, 2011

Good point. Somehow it eluded me that it's now 2011, and I think this thing has had a rough life.

Unfortunately, I bought it used and was only given one... Given that it is putting out an RF signal of some sort, I guess I'll just go to the stealership and ask if they'll reprogram it under the condition that I only pay if it actually ends up locking/unlocking my car. Not sure I want to shell out $50+ for absolutely nothing.

And yeah, the battery is in correctly. Thanks for checking

casm · Feb 18, 2011

anthrax323 said:
After about a week now of it not working, I reset the ECU (disconnected the battery) last night as a last-ditch effort. Still no dice.

Did you just disconnect the battery, or also go through the rest of the PCM reset steps?

Disconnect both battery terminals and touch them together for 30 seconds
Reconnect the Battery Cables
Turn Ignition Switch to the "On" position but DO NOT start the engine
Turn Headlight On"
Turn Headlights "Off"
Turn Ignition Key "Off"

To be honest, I don't believe that that's likely to affect anything as (IIRC) the programming that matches the fob is held in the keyless entry module, not the PCM. May be worth a shot, though.

Before I go pay $50+ to have someone reprogram it (seeing as you apparently need some special scanner to do it), are there any other basic diagnostics I can perform on the receiver in the dome light assembly, or is it safe to assume that the key fob just "lost" its programming? The dealership suggested this is a possibility, but barring some kind of accidental reset of the key fob on my part, I think it's a stupid idea.

Give this a shot: clean the battery-to-PCB contact in the key fob. Open up the fob and set aside the half of the shell that contains the batteries. Look at the PCB in the other half; pretty much dead centre on it will be a very obvious gold square. Get a Q-Tip and some rubbing alcohol and gently clean any accumulated crud off of it; if there's any sign of battery leakage or corrosion, white vinegar (be sure to clean up with alcohol afterwards) will take care of it. Next, do the same for the contact coming off of the batteries in the other part of the shell, and ensure (as best you can) that the battery contact actually is in touch with the gold square on the PCB.

Went through this a few times with the keyless on the last XJ, and doing both of the above helped to keep the problems with it to a minimum.

anthrax323 · Feb 18, 2011

casm said:
Did you just disconnect the battery, or also go through the rest of the PCM reset steps?

Disconnect both battery terminals and touch them together for 30 seconds
Reconnect the Battery Cables
Turn Ignition Switch to the "On" position but DO NOT start the engine
Turn Headlight On"
Turn Headlights "Off"
Turn Ignition Key "Off"

To be honest, I don't believe that that's likely to affect anything as (IIRC) the programming that matches the fob is held in the keyless entry module, not the PCM. May be worth a shot, though.

Give this a shot: clean the battery-to-PCB contact in the key fob. Open up the fob and set aside the half of the shell that contains the batteries. Look at the PCB in the other half; pretty much dead centre on it will be a very obvious gold square. Get a Q-Tip and some rubbing alcohol and gently clean any accumulated crud off of it; if there's any sign of battery leakage or corrosion, white vinegar (be sure to clean up with alcohol afterwards) will take care of it. Next, do the same for the contact coming off of the batteries in the other part of the shell, and ensure (as best you can) that the battery contact actually is in touch with the gold square on the PCB.

Went through this a few times with the keyless on the last XJ, and doing both of the above helped to keep the problems with it to a minimum.

Thanks for the tips - as always, it is much appreciated.

I think you're right about the PCM/ECU not being involved in the equation... I spoke to the dealership about diagnostic costs, which led to me inquiring about the keyless entry module in the dome light assembly. Turns out that it is indeed responsible for "knowing" the code, as it must be programmed upon installation/replacement (no codes are pulled from the PCM).

With regard to cleaning - the inside of the fob is absolutely spotless. No leakage, no deposits on the little gold square (just a scratch from the contact on the back half of the fob shell... I bent it up a bit more thinking it wasn't making contact, which it apparently was).

Weird thing is that the fob itself does seem to be working... It is emitting an RF signal, but unfortunately I cannot vouch for the correctness of said signal.

Just a side thought - given that people re-sell these things, there must be a way to "de-program" the fob/remote itself. Is there a button push sequence that wipes the codes from it? If so, I get the feeling that could have very easily happened while it was in my pocket while working in the shop on the day it stopped working.

casm · Feb 18, 2011

anthrax323 said:
Just a side thought - given that people re-sell these things, there must be a way to "de-program" the fob/remote itself. Is there a button push sequence that wipes the codes from it? If so, I get the feeling that could have very easily happened while it was in my pocket while working in the shop on the day it stopped working.

Nothing in the FSM indicates that; all that it mentions is that the fob has to be programmed via a DRB tool. About the only thing you can really do from the keypad of the fob is turn the doorlock horn chirp on and off.

JrTxJ · Feb 18, 2011

You can usually find new & used units on ebay for about $20. I had mine programmed at a local smaller dealer (that lost their franchise but still worked on Jeeps and have all their equipment) for $20 cash.

It's nice having a spare in case your other one dies or is lost.

anthrax323 · Feb 18, 2011

Once again, thanks for all the input guys... I agree on the 2nd fob note - I really need to get a second one.

But, alas, good news! I fixed it via a method that technically should not be applicable to the 2001 XJ with the 3-button remote.

http://www.ehow.com/how_5019251_program-keyless-entry-jeep.html

For grins, I tried the above procedure and it actually worked - my keyfob is once again operational! To summarize:

Get in the car, close the door, and put the key in the ignition (but don't turn it).
Open the driver-side door, and manually lock it. Keep it open.
Turn the key to the ON position, but don't start the car.
Press and hold the lock button on the fob for 5 seconds. In my case, holding it for a little over 1 second did the trick.

Figured I'd put the info in here in case anyone else with a late-model XJ runs into this issue in the future.

Now I'll be ordering another key fob online (~$35) and will take a stab at programming it this way... I'll report the results once I have them.

casm · Feb 18, 2011

anthrax323 said:
Once again, thanks for all the input guys... I agree on the 2nd fob note - I really need to get a second one.

But, alas, good news! I fixed it via a method that technically should not be applicable to the 2001 XJ with the 3-button remote.

http://www.ehow.com/how_5019251_program-keyless-entry-jeep.html

For grins, I tried the above procedure and it actually worked - my keyfob is once again operational! To summarize:

Get in the car, close the door, and put the key in the ignition (but don't turn it).

Open the driver-side door, and manually lock it. Keep it open.

Turn the key to the ON position, but don't start the car.

Press and hold the lock button on the fob for 5 seconds. In my case, holding it for a little over 1 second did the trick.

Figured I'd put the info in here in case anyone else with a late-model XJ runs into this issue in the future.

That's... Interesting

Never saw that before, and it doesn't appear to be in the FSM either. Wonder what the source on that was, but glad it worked for you.

Now I'll be ordering another key fob online (~$35) and will take a stab at programming it this way... I'll report the results once I have them.

Please do. My current fob is pretty beaten-up and I need a second one anyway, so I'd be interested to see how this works out for you.

anthrax323 · Feb 18, 2011

casm said:
That's... Interesting Never saw that before, and it doesn't appear to be in the FSM either. Wonder what the source on that was, but glad it worked for you.

Please do. My current fob is pretty beaten-up and I need a second one anyway, so I'd be interested to see how this works out for you.

Believe me, I'm baffled as well. My impatience means I'll likely go ahead and use the money I saved on re-programming to just buy a new fob locally (mark-up and all) this afternoon. I've been needing to get my spare key ring back in proper order anyway.

I can say, without a doubt, that the above process is indeed what fixed the issue in my case.

anthrax323 · Feb 18, 2011

Well, on my lunch break I stopped by the stealership and picked up another remote... Unfortunately, the above process did not program the new fob.

Must have been a fluke... Seems like the receiver may have been in a weird state that the above process somehow fixed. Guess I'll go ahead and return the new fob ($92 after tax), order one online, and wait patiently for it to arrive... Then have it programmed for less over at Key Harbor or something.

Spontaneous de-programming of keyless entry remote?

anthrax323

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