Never Trust A Good Battery

[steve2006]

Since buying the car my keyless locking hasn't worked and after checking the usual including taking the Battery out of the key fob and checking it on my meter which gave a correct reading of 3 volts I resigned myself to the fact it was gone forever.

I then came across an article for checking the Battery under working conditions and lo and behold when I pressed the button the Battery voltage dropped to 1.6 volts.

Bought a new Battery and........... IT WORKS!!!!!

SOOOOO Happy!

[JellyBean]

This info could prove useful indeed!

[steve2006]

This info could prove useful indeed!

Ok here's the method. You will need a multimeter to measure DC voltage

Open the fob to expose the Battery.

Put the black (negative) lead of the meter on the metal key.

Put the red (positive) lead of the meter on the top ot the Battery ( positive)

Check the voltage ( should be at least 3 volts).

This is the tricky bit.

Whilst the leads are still connected press the button on the fob keeping your eye on the meter reading.

if the voltage remains around 3 volts the Battery is OK. If it drops ( as in my case to around 1.5 volts) this indicates that the Battery is exhausted.

Or if you don't have a meter just buy a new Battery for a couple of quid and try that.

[japimport]

This info could prove useful indeed!

Ok here's the method. You will need a multimeter to measure DC voltage

Open the fob to expose the Battery.

Put the black (negative) lead of the meter on the metal key.

Put the red (positive) lead of the meter on the top ot the Battery ( positive)

Check the voltage ( should be at least 3 volts).

This is the tricky bit.

Whilst the leads are still connected press the button on the fob keeping your eye on the meter reading.

if the voltage remains around 3 volts the Battery is OK. If it drops ( as in my case to around 1.5 volts) this indicates that the Battery is exhausted.

Or if you don't have a meter just buy a new Battery for a couple of quid and try that.

I've got one of the ones with a single button on the side of the fob. I've unscrewed the little screw but can't seem to get the fob apart. How do you do it?

[steve2006]

This info could prove useful indeed!

Ok here's the method. You will need a multimeter to measure DC voltage

Open the fob to expose the Battery.

Put the black (negative) lead of the meter on the metal key.

Put the red (positive) lead of the meter on the top ot the Battery ( positive)

Check the voltage ( should be at least 3 volts).

This is the tricky bit.

Whilst the leads are still connected press the button on the fob keeping your eye on the meter reading.

if the voltage remains around 3 volts the Battery is OK. If it drops ( as in my case to around 1.5 volts) this indicates that the Battery is exhausted.

Or if you don't have a meter just buy a new Battery for a couple of quid and try that.

I've got one of the ones with a single button on the side of the fob. I've unscrewed the little screw but can't seem to get the fob apart. How do you do it?

Hi,

After removing the single philips screw I found the best way was to slide my thumbnail into the fob at the top of the loop where the keyring goes and prise it open or use a blade to assist.

One side should then open and can be removed to access the Battery.

Mine was very tight probably because it had never been opened before.

Good luck I hope it works for you,

Steve

[japimport]

This info could prove useful indeed!

Ok here's the method. You will need a multimeter to measure DC voltage

Open the fob to expose the Battery.

Put the black (negative) lead of the meter on the metal key.

Put the red (positive) lead of the meter on the top ot the Battery ( positive)

Check the voltage ( should be at least 3 volts).

This is the tricky bit.

Whilst the leads are still connected press the button on the fob keeping your eye on the meter reading.

if the voltage remains around 3 volts the Battery is OK. If it drops ( as in my case to around 1.5 volts) this indicates that the Battery is exhausted.

Or if you don't have a meter just buy a new Battery for a couple of quid and try that.

I've got one of the ones with a single button on the side of the fob. I've unscrewed the little screw but can't seem to get the fob apart. How do you do it?

Hi,

After removing the single philips screw I found the best way was to slide my thumbnail into the fob at the top of the loop where the keyring goes and prise it open or use a blade to assist.

One side should then open and can be removed to access the Battery.

Mine was very tight probably because it had never been opened before.

Good luck I hope it works for you,

Steve

Cheers Steve

just before I give it a go, I'll compare with you how mine works just to make sure it's normal and that a fresh Battery is actually required. I need to be probably less than a metre from the door and need to hold the button for a full second or 2 before the doors lock or unlock. So it works, I guess. Does this sound normal?

thanks again

Dave

[steve2006]

This info could prove useful indeed!

Ok here's the method. You will need a multimeter to measure DC voltage

Open the fob to expose the Battery.

Put the black (negative) lead of the meter on the metal key.

Put the red (positive) lead of the meter on the top ot the Battery ( positive)

Check the voltage ( should be at least 3 volts).

This is the tricky bit.

Whilst the leads are still connected press the button on the fob keeping your eye on the meter reading.

if the voltage remains around 3 volts the Battery is OK. If it drops ( as in my case to around 1.5 volts) this indicates that the Battery is exhausted.

Or if you don't have a meter just buy a new Battery for a couple of quid and try that.

I've got one of the ones with a single button on the side of the fob. I've unscrewed the little screw but can't seem to get the fob apart. How do you do it?

Hi,

After removing the single philips screw I found the best way was to slide my thumbnail into the fob at the top of the loop where the keyring goes and prise it open or use a blade to assist.

One side should then open and can be removed to access the Battery.

Mine was very tight probably because it had never been opened before.

Good luck I hope it works for you,

Steve

Cheers Steve

just before I give it a go, I'll compare with you how mine works just to make sure it's normal and that a fresh Battery is actually required. I need to be probably less than a metre from the door and need to hold the button for a full second or 2 before the doors lock or unlock. So it works, I guess. Does this sound normal?

thanks again

Dave

Hi Dave,

Yes they are a bit insensitive and the range is somewhat limited so yours seems to be working normally.

The actual "aerial" that picks up the keyfob signal is the heated rear window circuit, by some clever Lexus magic. So approaching the car from the rear seems to improve the response time.

Cheers,

Steve

[Chez]

This info could prove useful indeed!

Ok here's the method. You will need a multimeter to measure DC voltage

Open the fob to expose the Battery.

Put the black (negative) lead of the meter on the metal key.

Put the red (positive) lead of the meter on the top ot the Battery ( positive)

Check the voltage ( should be at least 3 volts).

This is the tricky bit.

Whilst the leads are still connected press the button on the fob keeping your eye on the meter reading.

if the voltage remains around 3 volts the Battery is OK. If it drops ( as in my case to around 1.5 volts) this indicates that the Battery is exhausted.

Or if you don't have a meter just buy a new Battery for a couple of quid and try that.

I've got one of the ones with a single button on the side of the fob. I've unscrewed the little screw but can't seem to get the fob apart. How do you do it?

Hi,

After removing the single philips screw I found the best way was to slide my thumbnail into the fob at the top of the loop where the keyring goes and prise it open or use a blade to assist.

One side should then open and can be removed to access the Battery.

Mine was very tight probably because it had never been opened before.

Good luck I hope it works for you,

Steve

Cheers Steve

just before I give it a go, I'll compare with you how mine works just to make sure it's normal and that a fresh Battery is actually required. I need to be probably less than a metre from the door and need to hold the button for a full second or 2 before the doors lock or unlock. So it works, I guess. Does this sound normal?

thanks again

Dave

Hi Dave,

Yes they are a bit insensitive and the range is somewhat limited so yours seems to be working normally.

The actual "aerial" that picks up the keyfob signal is the heated rear window circuit, by some clever Lexus magic. So approaching the car from the rear seems to improve the response time.

Cheers,

Steve

Hi,

I have just bought a 96 LS400 with two keyfobs that did not work properly, despite assurance from garage that they had new batteries in. I read the top post and checked the batteries. One was 0 volts and the other was 3 volts unloaded 2.7 volts when the buttons were pressed.

2 new batteries from Asda for £3 and they both work fine. The range is much better than yours at about 50 yards.

Cheers

Chez

[Nitmoi]

It works better from behind true but easily at 50 yards. Rear trunk less willing.

Put the fob against your forehead and try, it will extend the range. I saw this on top gear and it really works.