I replaced the tailgate of my 306 with a second hand unit ( i donot have a key), it worked on the central locking, this has now stopped working, i have replaced the batterys in the key but still the central locking does not work, i cannot open the tailgate, any ideas how i may solve this. thanks Richi

If recently I would take it back. I don't know what they did to fix your door. I do know that if some one just made it work, it could, and usually does, create other problems. Only way to tell is to remove the panel and see what the did. If they added wire or sliced to make it work. This has to repaired first, then replace the part that really is broken. I see it all the time.

Locking/Unlocking the doors from the outside
This is done using the RENAULT Card; see the "RENAULT Card" information in Section 1.
In certain cases, the RENAULT card may not work:
- if the RENAULT card battery is weak, flat, etc.
- if equipment operating on the same frequency as the card (mobile phones, etc.) is used;
- vehicle located in a high electromagnetic radiation zone.
It is then possible:
- to use the key integrated into the card to unlock the front left-hand door;
- to lock each of the doors manually;
- to use the interior door locking/unlocking control (refer to the following pages).
Using the key integrated in the RENAULT card
Insert key 1 into the lock in the driver's door and lock or unlock. Locking the doors manually
Turn screw 2 with the door open (using the end of the key) and close the door.
This means that the doors are then locked from the outside.
The doors may then only be opened from the inside or by using the key in the front left-hand door. Interior locking/unlocking door control
Switch 3 controls the doors, boot and, depending on the vehicle, the fuel filler flap simultaneously.
If a door or the tailgate is open or not closed properly, the doors and tailgate lock/unlock quickly.
If you need to transport objects with the boot open, the other opening elements can still be locked: with the engine stopped, press switch 3 for more than five seconds to lock the other opening elements.
Locking the doors without the RENAULT card
For example, in the event of a discharged battery or the RENAULT card temporarily not working, etc.
With the engine switched off and an opening element (door or boot) open, press and hold switch 3 for more than five seconds.
When the door is closed, all the doors and the tailgate will be locked.
Unlocking the vehicle from the outside is only possible with the RENAULT card in the vehicle's access zone or using the key integrated in the RENAULT card.
Door and tailgate status indicator
With the ignition on, the warning light integrated in switch 3 informs you of the locking status of the opening elements:
- indicator light on, the doors and tailgate are locked,
- indicator light off, the doors and tailgate are unlocked.
When you lock the doors, the indicator light remains lit and then goes out.

https://manuals.co/workshop/opel/corsa/opel-corsa-1997-2000-workshop-manual-haynes/5530701/3

You might have just blown the fuse, otherwise it could be the control module wiring has been damaged.
Check tthe wiring in the manual above.

Open trunk problem

Inspect very closely, there will be a cover over the manual key lock. The cover will pry off, be careful not to damage the paint. This will enable you to open the door, The actual fault is probably the central locking solenoid which is part of the catch assembaly. Buy the unit new as a second hand one will just have the same weakness.

Try a graphite lock lubricant. It works better than wd40

Telephone: Fax: VAT Registration No.:
Infrared remote control
NOTE: Infrared emitter can be seen at front edge of key.
System operation
Switch ignition ON. Ensure clock LED illuminates for 3-5 seconds. Pressing key lock button once activates central locking and alarm. Pressing key lock button twice within 3 seconds activates double locking system.
Programming
When
Key batteries completely discharged. Key batteries not replaced within 15 seconds. Key added or replaced. System malfunction.
How
Obtain all keys fitted with remote control. Turn ignition switch to position I. Wait approximately 10 seconds. Ensure clock LED illuminates.
NOTE: LED illuminates for approximately 5 seconds.
Switch ignition OFF and remove key, while LED illuminated. Programming mode activated for approximately 20 seconds (LED illuminated). Proceed as follows: Point key at receiver (located near interior lamp). Press and hold unlock button Fig. 1 [1]. After approximately 1 second key LED will flash once [3]. Press lock button 3 times Fig. 1 [2]. Release unlock button Fig. 1 [1]. Continue to point key at receiver until LEDs in clock and key have flashed 5 times. Ensure LED remains illuminated. Repeat above procedure within 20 seconds to program remaining keys. To exit programming mode and extinguish clock LED: Switch ignition ON and OFF. Wait approximately 20 seconds.
NOTE: A maximum of 4 keys can be programmed. Fig. 1
Radio frequency remote control
System operation
Switch ignition ON. Ensure clock LED illuminates for 3-5 seconds.


Pressing tailgate release button twice within 3 seconds unlocks the tailgate - if fitted. Pressing key lock button once activates central locking and alarm. Pressing key lock button twice within 3 seconds activates double locking system. Interior lamp illuminates when disarming system.
Programming
When
Key added or replaced. System malfunction.
How
Obtain all keys fitted with remote control. Fasten seat belts and close all doors. From position I, turn ignition switch as follows: To position II. To position I. To position II. To position I. To position II. To position I. Programming mode activated for approximately 20 seconds. LED or fog lamps ON warning lamp illuminates (some models) or the system will emit an acoustic signal to indicate start of programming mode. Proceed as follows: Type 1: Press and hold unlock button Fig. 1 [1]. Type 2: Press unlock button Fig. 2 [2]. Ensure clock LED or fog lamps ON warning lamp flashes (some models) or wait for acoustic signal (indicates correct programming). Wait 2 seconds. Repeat above procedure within 20 seconds to program remaining keys. To exit programming mode: Switch ignition ON. Wait 20 seconds.
NOTE: A maximum of 4 keys can be programmed.

the gas flap is operated with the central locking,stand at rear of car with tailgate open,just inside to the right,under the floormat you will find the central locking pump.but first renew the batteries in the remotes then unlock the car with the key and hold the key over for 30 secs, the windows may go down,
then lock the car with the key and hold over for 30 secs,the windows may go up and the sunroof,if fitted will close,then unlock with remote button held down for 30 secs,this will reset alarm/central locking.
if you need to get to gas flap, pull carpet away in boot behind flap area and pull wire to unlock....

central locking on my 93 corsa with standard key, not electronic type as used on later models, all doors are locked and refuse to open, ive checked fuse and thats ok, doors refuse to open from inside the vehicle and from outside, only the tailgate will open from the key, any ideas ,,, thanks dave

Unfortunately, This is a very common problem with Ford Explorers! Ford replaces the locks when it encounters this issue. I managed to unseize my passanger door and tailgate lock, but the drivers door lock is broken beyond repair. You can purchase new remotes for your explorer and program them very easily. Just google ford key fobs...