GP688 firmware upgrade

[Causilgey]

I need to firmware upgrade a number of GP688 and my RLN4008 Rib and RKN4074B lead don't appear to work for this operation. Please can someone suggest a way to do this?
Thanks

[Causilgey]

From what I can see, the only difference btween my lead and one used by a main dealer is that pin 3 is missing on the radio connector. Looking at your pin outs that should make no difference.

[Andreas]

1.)Never use a RIBLESS cable to make a firmware update.
2.)Always save the tuning data and write down the temperature compensation data of each radio,before you make the update.

Andreas