Battery re-set-how long do you disconnect for?

[Ingwe]

Followed the thread about getting remote fob working again by disconnecting negative lead on vehicle battery for a while then reconnecting it. Can anyone let me know how long one should leave the negative lead disconnected? I tried this tip earlier and left the negative lead disconnected for 5 minutes. However, when I connected it up again, everything on the van worked but not the fob.
I was thinking that maybe there is a minimum period of time to leave it unconnected before reconnecting?

 

[pappajohn]

Flat fob battery?

 

[Ingwe]

Flat fob battery?

No. Checked with multi-meter but also took the precaution of replacing with a new CR2032.

 

[Raul]

Put the key in ignition, turn it on, but not cranking. Press both buttons on the fob at once. It will reset.

 

[Ingwe]

Raul-thanks but this didn't work. Put key in ignition, put it to on, lights etc came on, pressed the lock and unlock buttons simultaneously for 5 seconds then turned off ignition, withdrew key then tried the remote fob. Nothing.

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[Raul]

When you changed the battery, have you observed the polarity? If the chip is energised ( both buttons pressed briefly) and ignition is on, it resets the chip. The transponder is near ignition so it should work. Maybe defective or bad contacts on the fob.

 

[Ingwe]

Yes, I observed the polarity when changing the batttery. In fact, the battery only fits into the battery holder in the fob, if the polarity is correct. The fob ceasing to work was quite sudden, not being dropped or anything like that. Is there a way of testing the fob to see that the transponder is giving out a signal?

 

[Gromett]

Dodgy switch in fob is a possible candidate. I got a new case for mine and it came with replacement switches. This indicates to me that switch failure in fobs is quite common.