2006 C180 sport locking from distance with fob but not unlocking using RF of IR

[doctorgonz0]

Hi folks. I bought an 06 C180 sport in the summer and over the last week have had problems when using the keyfob to lock/unlock car. Now the car wont unlock at all, even with the key pushed right against the IR sensor. I have to use the emergency key which obviously sets the alarm off when the door is opened which is less than ideal given the time I leave for work in the morning. I've checked all the fuses that are linked to the central locking and I've checked the key is emitting IR using my phones camera. I'm assuming the RF receiver is fine due to the car locking from a good distance away. Any help or ideas would be greatly appreciated with this.

 

[Benzowner]

Have you checked the batteries in the key? Although transmitting, it may be a weak signal and not sure, but lock is the default position for security and maybe does not require such a strong signal.

 

[doctorgonz0]

Have you checked the batteries in the key? Although transmitting, it may be a weak signal and not sure, but lock is the default position for security and maybe does not require such a strong signal.

Yeah, I forgot to mention that. Batteries were changed yesterday to no avail

 

[markjay]

Welcome.

The fob has for separate functions.

1. Immobiliser transponder - that's a tiny chip that does not require battery power, and talks to the Electronic Ignition Switch (EIS) and allows the engine to be started when the fob is inserted into the ignition switch.

2. Emergency key - that's a mechanical key blade that can be used to unlock the driver's door or the boot/tailgate. It does not disable the alarm though, nor can it be used to start the engine. It is recommended to keep the locks lubricated, and use the key on both the driver's door and tailgate from time to time to ensure that the lock's mechanism does not seize.

3. Radio Frequency (RF) lock/unlock - these are the buttons on the fob. They should work from a reasonable distance - a hundred feet or so. If it does not work, try replacing the batteries, try the spare keyfob, or try at a different location (i.e. in case of RF interference in the area). Also, the functionality of the unlock button can be selected as either 'open all doors on first press', or 'open driver door only on first press, open all other doors on second press' (anti car-jacking).

4. Infra Red (IR) convenience closing / summer opening - if you place the small IR LED at the edge of the fob against the rectangular IR receiver of the driver's door handle, then press and hold either the lock button or the unlock button, then all the windows will open or close respectively. This feature is poorly implemented, it only works when the IR LED is in very close proximity to the receiver, and it doesn't work in bright sunlight (unless you shield it with your hand). In addition, the soldering inside the door handle have been known to fail, and then this feature won't work at all (check on YouTube how to re-solder the contacts in the IR receiver). But the first things to try is replacing the batteries, checking with the spare keyfob, and cleaning the IR LED and IR Receiver.

 

[markjay]

Your issue could be as simple as the unlock button on the fob not working. Do you have a spare keyfob you can try?

 

[markjay]

Oh, and seeing as you have the M271 engine, remember to have the camshaft sprocket wheels' teeth checked (if not done so already). Nothing to do with the unlocking issue, obviously.

 

[doctorgonz0]

The fob has for separate functions.

1. Immobiliser transponder - that's a tiny chip that does not require battery power, and talks to the Electronic Ignition Switch (EIS) and allows the engine to be started when the fob is inserted into the ignition switch.

2. Emergency key - that's a mechanical key blade that can be used to unlock the driver's door or the boot/tailgate. It does not disable the alarm though, nor can it be used to start the engine. It is recommended to keep the locks lubricated, and use the key on both the driver's door and tailgate from time to time to ensure that the lock's mechanism does not seize.

3. Radio Frequency (RF) lock/unlock - these are the buttons on the fob. They should work from a reasonable distance - a hundred feet or so. If it does not work, try replacing the batteries, try the spare keyfob, or try at a different location (i.e. in case of RF interference in the area). Also, the functionality of the unlock button can be selected as either 'open all doors on first press', or 'open driver door only on first press, open all other doors on second press' (anti car-jacking).

4. Infra Red (IR) convenience closing / summer opening - if you place the small IR LED at the edge of the fob against the rectangular IR receiver of the driver's door handle, then press and hold either the lock button or the unlock button, then all the windows will open or close respectively. This feature is poorly implemented, it only works when the IR LED is in very close proximity to the receiver, and it doesn't work in bright sunlight (unless you shield it with your hand). In addition, the soldering inside the door handle have been known to fail, and then this feature won't work at all (check on YouTube how to re-solder the contacts in the IR receiver). But the first things to try is replacing the batteries, checking with the spare keyfob, and cleaning the IR LED and IR Receiver.

thanks for the reply. The batteries were replaced and didn't make any difference unfortunately.
As for RF interferance, I'm guessing that's not the issue as i can still lock my car from inside my flat and I've never had any problems locking/unlocking the car up until a week ago give or take.
I've checked to see if the IR window function was working and that's not working either but having never tried it before, I can't say whether this is a new problem. Unfortunately my spare key has a missing microswitch for the unlock button so is of little use to me in this situation. As i said, thanks for your advice and I really appreciate the help with this

 

[doctorgonz0]

Your issue could be as simple as the unlock button on the fob not working. Do you have a spare keyfob you can try?

thanks for the reply. the microswitch is missing on the spare key so no help there unfortunately. The unlock has worked maybe twice since yesterday but that was standing right next to the car and repeatedly pushing the button but that doesnt seem to do anything at all now either.

 

[markjay]

Looks like you'll need to take the car to the garage for diagnosis... either that, ot bite the bullet and order a complete spare key (£200-£250 from a dealer), so that you can eliminate the fob (and the microswitch) as the source of the issue.

 

[doctorgonz0]

Looks like you'll need to take the car to the garage for diagnosis... either that, ot bite the bullet and order a complete spare key (£200-£250 from a dealer), so that you can eliminate the fob (and the microswitch) as the source of the issue.

thanks again. I can get access to a diagnostic machine as soon as i can get in touch with my pal so as far as I know it should flag up any problems with the AAM. If there was a problem with the AAM, I'm guessing i would lose all function from the fob rather than just unlock and boot opening. I've found a company in London that will refurbish the key for about £40 (checking circuitry and replacing microswitches). Would that be an alternative to replacing the key completely?

 

[190]

One of my keys started playing up recently which was no surprise as the battery hadn't been changed in over 5 years. What did surprise me is the old battery was only 0.2 volts down on the new one which suggests that the fobs are quite sensitive to battery voltage. I would measure the new one just to make sure it's up to scratch. Assuming it's the same CR2025 I measured a new Panasonic battery at 3.2 volts.

 

[doctorgonz0]

One of my keys started playing up recently which was no surprise as the battery hadn't been changed in over 5 years. What did surprise me is the old battery was only 0.2 volts down on the new one which suggests that the fobs are quite sensitive to battery voltage. I would measure the new one just to make sure it's up to scratch. Assuming it's the same CR2025 I measured a new Panasonic battery at 3.2 volts.

looking at the new batteries that were installed yesterday (which were supplied by a local parts dealer) they are CR2032 and marked 3v. Ive just swapped over the battery assembly from the spare key which has the panasonic 2025's in it and presto, car unlocks from inside my flat. I cannot thank you and the other contributors enough for this. you guys are the heros we need, not the ones we deserve lol. Thanks again guys.

 

[markjay]

thanks again. I can get access to a diagnostic machine as soon as i can get in touch with my pal so as far as I know it should flag up any problems with the AAM. If there was a problem with the AAM, I'm guessing i would lose all function from the fob rather than just unlock and boot opening. I've found a company in London that will refurbish the key for about £40 (checking circuitry and replacing microswitches). Would that be an alternative to replacing the key completely?

Tricky one... because you can't really test the fob they will send you (i.e. if the refurbished fob still does not unlock the car, then you can't tell if its because they didn't do a good job, or because there's a fault with the AAM). But for £40, I would go with that option first - sending the the spare fob with the missing microswitch.

 

[doctorgonz0]

Tricky one... because you can't really test the fob they will send you (i.e. if the refurbished fob still does not unlock the car, then you can't tell if its because they didn't do a good job, or because there's a fault with the AAM). But for £40, I would go with that option first - sending the the spare fob with the missing microswitch.

thanks again. sorted now though thanks to 190's advice. turns out it was the new batteries. they were replaced with 2032's as thats what was in it before but the spare key had the 2025's in it. As 190 said, the fobs seem to be very particular about the voltage o it msay be the case that the 2032's that were in it before happened to have the correct voltage and these new ones didnt cut it. many thanks for taking the time to reply to my messages though.