Technical The definitive remote locking thread

[renaultvation]

I have seen hijacked threads on this subject and other threads which have petered out without any conclusion, so I thought I would start a thread about remote locking and hopefully we may find a few answers.


My 94 Cabrio has non-functioning remote locking. It didn't fail overnight, but gradually got worse over a period of time until it ceased working altogether. The central locking still works fine. I assumed it was just a failing battery, so replaced them both, but it made no difference. The little light flashes on the side of the fob, but that doesn't mean that the infrared is working as that is invisible to the eye. However, I was able to check it is working by looking at it through a digital camera, which does show infrared (try it, it really works).


Having given the key a clean bill of health I tried to reprogram the sensor in accordance with the handbook. The led next to the sensor flashed as it should and I pointed and operated the key as per the instructions, but it had no effect. I removed the sensor and checked it for broken connections, but didn't identify any, so put back together. So I am now in the position of knowing that the key works and the led next to the sensor works, but the remote locking does not.


Has anyone ever resolved this problem and can we see if we can beat the record of 5 responses to a remote locking thread?

 

[Didge3]

Well as you know, my '94 has non functioning remote locking too
I believe later cars use a different system using RF rather than IR that our earlier models use. I'm just putting this here for future reference really.

I also confirmed my key is working, the red light flashes upon pressing the button and pointing my phones camera at the IR sensor you can see it 'flashing' purple(ish) but no response from car. Also tried reprogramming with no luck.
If I get round to it tomorrow I will check the voltages behind the in sensor in the car to see if its getting power but I don't know where to go from there...

 

[simon_16vpunto]

According to one of the fiat techs at work, there should be a code card with a 4 digit code. This is then programmed in a sequence or summin.

I'm not so sure, my car has every single bit of history/ books/ ISR pish etc since new but no code card so I'm not sure it come with one.

When I'm back in Monday I'm gonna see if I can get a code card from parts

 

[Didge3]

I have a code card that came with my car but I assumed it was for the radio... I don't know how you'd use said code with the key or the cars system

This is said card, on the other side it has a code and some other numbers but all the words are in Italian so I don't know what the other numbers are referring to,

 

[Didge3]

Forgot to add, checked the voltages behind the sensor thingy in the car. With the ignition off I'm getting 12v to the sensor so its not that...

 

[renaultvation]

Sounds like you have exactly the same issue as me. Our cars are similar in so many ways!

 

[Didge3]

A miracle has happened and I have working remote locking

Fortunately it was a fairly simple fix. After I confirmed power was going to the in car sensor and the central locking works fine I figured it MUST be the key??

So I full disassembled the key, lightly sanded the battery contact points and cleaned them up with rubbing alcohol which didn't work. My key's LED flashes and looking through my phones camera the IR hole on the front flashes purple ish when the button is pressed

But after having many a flat car battery (car hasn't been ran for more than half an hour for months so the battery never gets charged properly) I thought, even though a multimeter will say your car battery is holding 12v, when you put a load on said battery for example your starter motor the voltage can drop to 5v if the battery isn't charged, the same applies to all batteries so I decided to test the batteries in my key.
Stacked up as they are in the key, each battery being 3v showed a reading of just over 6v, I then nabbed a random 2W LED out of my electronics collection and attached that to the batteries, it lit up but the multimeter reported the batteries dropping to just 1.8v.

So I ordered some new CR2016 batteries from Amazon, Panasonic branded with an expiry of 2021 for £1.20 so not much of an investment and put them in the key, however this time the keys LED didn't even light! I checked the batteries weren't in the wrong polarity first but I then noticed the way they were sat in the key the negative terminal must barely make contact with the circuit board, so I put a small piece of folded up tin foil on the negative battery terminal like this,



Ensure it doesn't extend past the battery (I actually folded it more after that picture so it sits in the centre of the battery) so it doesn't bridge any connections on the circuit board when you close your key up.



The big round connector is the negative side and the small rectangle is the positive connection, so to make a better connection you should also bend the little metal tab that runs under the battery up to press against that more like so,



After all this I put my key back together (carefully so the tin foil didn't slide off the battery) and now the red LED flashes MUCH brighter than before.

Went out to the car and voila, unlocks at the press (and hold) of the button :slayer:

The remote locking is crap if I'm honest but it does function

So first thing I'd check if yours isn't working is that the battery is making good connection, bend the metal strip that runs under the battery up so it press against the circuit board better and put a small piece of folded tin foil on the battery, if this works great, if not test your battery if you have a multimeter and something that will put an electrical load on it, if you can't do that I'd just buy some new batteries, they're cheap online (although I'd buy branded ones over ones you've never heard of).

It seems to me that the plastic casing over time looses its clamping force that presses the battery into the circuit board.