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Let's look at what we're really translating here.
Comprenons bien ce qu'on est en train de traduire.
Dans l'informatique, pour faire communiquer deux les appareils Bluetooth, on doit d'abord effectuer un jumelage, ou un couplage. Perso, je préfère et utilise "jumelage". Donc le "password"ici n'est rien d'autre que le code de jumelage par défaut, en effet souvent "0000". Si on veut parler de façon compréhensible aux francophones, tout en étant en phase avec le monde de l'informatique et ses termes devenus "stardardisés", il convient de dire "code de jumelage (ou couplage) par défaut".

Please note that the EN in this source text is flawed, and this doesn't in fact seem to be a 'password' at all, but as typical on these devices, a PIN number or 'code'. On this assumption, the whole thing can be made a lot more concise!

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Note added at 1 heure (2016-12-10 18:19:52 GMT)
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Note that they are usually called 'code PIN', but in order to avoid the anglicism, I think in the particular context here it would be acceptable to omit the 'PIN'

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Note added at 2 heures (2016-12-10 19:10:38 GMT)
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Even though as Daryo points out, strictu sensu this sort of thing is not a code at all (which is a system of cyphers), the word 'code' is, however, in universal use in real-life everyday language in this sort of sense; usually, a short, easy-to-remember 'secret' code with strictly limited security, which is used for things like bank cards (please enter your code / PIN) and mobile phone unlocking.
In this very specific context, I have never seen 'password' used on either an EN or a FR phone; it is almost always something along the lines of « saisir votre code PIN / code SIM » etc.

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Note added at 1 jour3 heures (2016-12-11 20:11:15 GMT)
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I find it astonishing that anyone could have the slightest doubt about he dangers of straying from a literal rendering of the source term, even when that is clearly in error.
My only intention here was to suggest what would be a correct translation of the PROPER term, IF the source text had been correctly draughted by a native speaker of EN.
Obviously, it is up to Asker to deal with the deontological question of when, if ever, a translator should correct a source-text error or not, and how to deal with this as customer level.
I believe my only role here is, as a native-speaker of the source language, to highlight my perception of the source text meaning, including any possible errors; and then to indicate my suggestions as to ways to convey that in translation, alebit as a non-native speaker of the target language, BUT with no small exposure to it, especially in the specialist fields involved. Obviously if I can bring my specialist knowledge to bear on this question of "bridging the gap", then so much the better!