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[pahaahv]

Hi, totally new user here from Estonia, having the same issue here in 2024 in my Opel Omega 1997 pfl. The remote works for 2-3 times and then the car forgets it so I have to reprogram it again. Does anyone know if the author found a solution back in the day or what it could be? I can see from the leds that the fob is operating. I was wondering if there could be any fuses related to the system. I also have a problem seldom but still that the car is cranking but doesn't start. Fixed with locking the car 1-2 times.

[TheBoy]

Split into new thread, as this is not a transponder issue like original thread

[TheBoy]

So post 1995 cars use an RF fob with a rolling code system.

If it stops working, and has to be resync'd to get it to work, its likely it's losing where it is in it's rolling code.  A few possibilities:

Knackered battery holder, particularly where the battery holder pins go into the PCB. Seems to afflict the integrated horseshoe style keys more than the separate fob type.

The key is a clone, or has been cloned, and the other cloned one is upsetting the rolling code. Some key programmers clone keys, rather than do it properly.

The fob is randomly pressing teh button itself, either through vibration or water ingress etc. Causing the key to go out of range.


Using your spare key will help pin down the problem.


In my experience, it's less likely to by the receiver side - the Central Locking or Alarm (depending on spec) ECU behind the RH kick panel.  Although these sometimes get water ingress, that tends to cause the system to just not work.

[pahaahv]

So post 1995 cars use an RF fob with a rolling code system.

If it stops working, and has to be resync'd to get it to work, its likely it's losing where it is in it's rolling code.  A few possibilities:

Knackered battery holder, particularly where the battery holder pins go into the PCB. Seems to afflict the integrated horseshoe style keys more than the separate fob type.

Yesterday I examined the fob and correct, a massive cold joint of the negative terminal. The battery was also only 2.7V. Fixed it and now a well working fob so far, even though I'd like to change it to something cleaner and sturdier. Many thanks!

[pahaahv]

So, for a while I had the fob working very well. The resoldering and new battery worked wonders and opened the car from about 10 meters away. One day though it stopped working again. No cold solder joints seen this time, the car just does not respond to fob button presses.

Tried to re-teach the car with ignition on - it doesn't respond at all.

The fob battery is rather new, voltage 3,1V, the leds on the fob light up brightly. What and how to check?

[TheBoy]

carefully check the metal pins from the PCB to battery contacts - they often snap.  If that's the case, bodge however you deem fit (I tend to solder a spare piece of leg from a resistor to the batt holder, then solder that to PCB.

Once done, give it some mechanical strength by putting a blob of glue between batt holder and PCB, but only once you're sure it's working.  I personally use hot glue for this.

[pahaahv]

Would the leds still work if the pins are snapped? I measured voltage on the solder blobs of the pins and also got 3.1V. I guess I could fiddle around with it and see if the pins don't give contact when the fob is assembled..

[Doctor Gollum]

Have you tried the remote locking in a different location?

It could be a local interference issue.

[pahaahv]

Have you tried the remote locking in a different location?

It could be a local interference issue.

Yup, everywhere. In car, out of car, near home, 100km from home, left of car, right of car.

[johnnydog]

So post 1995 cars use an RF fob with a rolling code system.

If it stops working, and has to be resync'd to get it to work, its likely it's losing where it is in it's rolling code.  A few possibilities:

Knackered battery holder, particularly where the battery holder pins go into the PCB. Seems to afflict the integrated horseshoe style keys more than the separate fob type.

The key is a clone, or has been cloned, and the other cloned one is upsetting the rolling code. Some key programmers clone keys, rather than do it properly.

The fob is randomly pressing teh button itself, either through vibration or water ingress etc. Causing the key to go out of range.


Using your spare key will help pin down the problem.


In my experience, it's less likely to by the receiver side - the Central Locking or Alarm (depending on spec) ECU behind the RH kick panel.  Although these sometimes get water ingress, that tends to cause the system to just not work.

I had a very similar issue with my 2002 Elite. The key remotes would work randomly - sometimes ok for days / weeks, but then be totally dead - as if they had lost communication with the car. The batteries were changed, with no improvement. I could resync the keys, and it would be fine - sometimes for a few minutes or even several days, but would then fail to lock or unlock the car at random. I'd had few other issues with the interior light staying on, and the headlight warning buzzer, but that was as a result of previous water ingress via the sunroof which was eventually cured.
I had the keys reprogrammed but it still happened quite randomly.
I ended up changing the central locking ECU in the RH kickpanel with one from an identical car (the ident no. needs to be the same), and swapped the fob part of the keys from the donor car into the original blades / horseshoes, and it has worked perfectly ever since. I believe the water ingress from the sunroof may had actually damaged the ECU.
So whilst it may be rare that the ECU fails, it can happen and therefore may be an option worth exploring.

[Doctor Gollum]

Have you tried the remote locking in a different location?

It could be a local interference issue.

Yup, everywhere. In car, out of car, near home, 100km from home, left of car, right of car.

Lol, ok

At least it rules that out

[TheBoy]

I had a very similar issue with my 2002 Elite. The key remotes would work randomly - sometimes ok for days / weeks, but then be totally dead - as if they had lost communication with the car. The batteries were changed, with no improvement. I could resync the keys, and it would be fine - sometimes for a few minutes or even several days, but would then fail to lock or unlock the car at random. I'd had few other issues with the interior light staying on, and the headlight warning buzzer, but that was as a result of previous water ingress via the sunroof which was eventually cured.
I had the keys reprogrammed but it still happened quite randomly.
I ended up changing the central locking ECU in the RH kickpanel with one from an identical car (the ident no. needs to be the same), and swapped the fob part of the keys from the donor car into the original blades / horseshoes, and it has worked perfectly ever since. I believe the water ingress from the sunroof may had actually damaged the ECU.
So whilst it may be rare that the ECU fails, it can happen and therefore may be an option worth exploring.

In this case, its most likely the battery connector or fob dry joints, causing the battery to occasionally disconnect which resets the rolling code, thus needing resyncs.

[TheBoy]

Would the leds still work if the pins are snapped? I measured voltage on the solder blobs of the pins and also got 3.1V. I guess I could fiddle around with it and see if the pins don't give contact when the fob is assembled..

Its more if the connection breaks at any point, including when pressing a button, or even releasing a button.

If you are sure the fob(s) are OK, that then points to the receiver (Alarm ECU or Central Locking ECU depending on spec), which can be prone to water ingress due to windscreen leaks and scuttle drain leaks (LHD only)