Hello all

2002 LS430 in the UK.

Last Friday, I actually had a message on the dash saying:

REPLACE SMART KEY BATTERY

To my lasting regret, I did not appreciate just how low the battery actually was, because it was completely dead yesterday...anyway, i had a spare CR2032 battery in the house, so swapped it out...

GOOD NEWS - keyless entry works. I can touch the door handle, and the car unlocks. It starts and drives like normal.

BAD NEWS - none of the buttons on the fob (lock / unlock / trunk) work? If you press them the red LED flashes once, so the battery is okay - well - the car unlocks and starts so it must be - but no buttons? Huh?

Any ideas and advice from the floor much appreciated.

Thanks
Greg

 

Hey, just noticed - nearly 3 years without a post! Top lurking.

 

I don't think I've ever pressed the buttons on my fob to know if they work or not.

Two (possibly dumb) suggestions:

- Make sure you installed the battery polarity correctly.

- Install a fresh battery rather than one you had sitting around the house. (Batteries I have laying around often have an unknown history / age.)

 

The polarity must be correct since his smart function works.

That's a good point, maybe his new battery is still too weak.

I just replaced a 100% dead battery in my spare key fob too, everything 100% works, so there is nothing you have to do special.

 

Are you sure the battery isn't in backwards? Before you insert the button/battery unit back into the black case, press on the buttons to see if they work. IIRC, the "+" side of the battery faces up. I've also used a different battery. I think it was a CR2025 (same diameter but slightly thinner than the CR2032, but I had a bunch on hand and it worked).

 

Thanks for the replies so far..

Okay, so I just tried reversing the polarity of the battery - that didn't work at all. LED does not come on.

Tried a new battery - exactly the same.

I think it is limited to just this key, as my missus' key works just fine.

Stumped...any other ideas?

 

If the other key fob works fine you can likely rule out a defect in the car itself. And since the problem fob worked fine before the battery switch then something about the battery switch may have affected the problem fob.

If you have switched batteries between working fob and problem fob with no difference in operation, then it most likely is defect with the problem fob and not with a bad or incorrectly mounted battery.

I'd take both fobs out of their shells and try working the buttons with controllers out of the shell, checking the fob function after you remove the internal controller from the outside shell.

Then take batteries out of both fobs and examine the fobs side by side looking for some mechanical break or misalignment in the problem fob.
Look at the internal buttons - do the internal buttons depress easily and look OK. Look at electrical contacts in the battery mount point. Look for bits of dirt and dust that may be blocking the buttons in the shell or disrupting electrical contact where the battery is inserted. Are the battery contacts intact and not bent. missing or damaged and do they look exactly like the contacts in working fob?

These things collect a lot of dirt and dust.

If everything looks OK on the fob mechanically, as an alternative you may need to research if there is any learning or registering process for a key fob, if it has somehow become unregistered from the car - I am not sure about this part so I will defer to other posters that will likely know way more about this. This seems unlikely because the fob still opens and starts the car. Points more to a mechanical break specifically concerning the buttons but who knows. Its a complicated car. I would try that after I had verified that the fob looked OK internally and before I bought a new fob

 

+1 on trying the buttons with the inner assembly removed.

Could the assembly itself be reversed in the shell? I can't recall from the last time I swapped my battery, but I think it's possible to put the whole assembly in backwards so the button contacts face the wrong way.

 

Hi thinkin and others, I should have mentioned..when I tried earlier with a brand new battery, this was indeed with the key disassembled, so was just the transponder itself.

No joy, sadly.

 

You guys caused me to wonder about my keys. I have an 04, so don't know if the keys are same as 2002.

I have two master keys and a sub key. I had never even tried to use the sub key since I bought the car 4 years ago. Needless to say, it didn't work. Installed a new battery (the old one was upside down) and it worked. I then realized that the sub key is essentially a valet key. It has manual button to open the doors and while the car can be driven, it will not operate the glove box or trunk with the mechanical slide-out key.

Then I found that the master key, which I basically never even take out of my pocket, will allow the windowns and roof to be opened if you push the button and hold down for 3 seconds. A function I didn't remember or even use.

My lesson learned. I should change the batteries in the keys every three years or so and not wait for them to run down.

 

Sorry, I'm out of ideas. I popped mine apart again to check ('04, but I think it's the same unit) and I can't see how the circuitry for the buttons could be easily damaged just by replacing the battery. It's fairly robust.

It may be just a bizarre coincidence that the button portion failed at the same time, or perhaps some component in the circuitry was failing and borderline and the voltage from the fresh battery sent it over the edge. Good luck with it!

 

Thanks guys. Might be worth giving my dealer a bell and see if it might be something that's resolvable.

 

Last thing you could try is to use a pencil eraser and rub it on the electrical contacts that contact the battery, then reinsert the battery.

 

Sounds like the fob itself...

USA guys, remember that you got smart access after it was released in some other countries like UK/South Africa...
I have smart access in my 2001 LS430...

The fob is not a big expense and you can get it from eBay and reprogram it (you can get the one from USA for '04/'05/'06 LS...)...you would also have to cut the blade on it...

 

do not order one off of ebay.the smart key cannot be reprogramed,you have to order a new smart key.been there and done it.