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Discussion Starter · #1 ·
Hello to all,
Last Thursday night I took my '98 528i for a spin and after returning home I accidentally dropped my cell phone between the seat and the the shift area. I turned on the reading light on the drivers side and retrieved the phone. Unfortunately I forgot to cut the reading light back off and went to get in the car the next day and my keyless entry wouldn't unlock the car. I put the key in the door and unlocked it that way, which tripped and deactivated the alarm. The car did start as usual but that is when I had noticed that I had left the light on over night. Since this has happened I have only been able to lock and unlock the car by putting my key in the door. I replaced the battery in the keyless entry to no avail. Like I said the alarm is working and functioning as normal. I know the key operates on an RF bandwidth so thought it could perhaps be the RF transmitter in the unit itself or possibly the RF receiver in the car has gone bad. But keeping in mind the fact the battery was powering the reading lamp all night long I am wondering if something like keyless entry would fail if the battery was not producing the proper amount of voltage for the car. My next step is going to be to have the battery tested and we'll see where that goes. Has anybody experienced this or have any insight as to what it might be? :thumbup:

Thanks!!
 

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The reading light should have turned off after 16 min. If it did not, you have other problems.
 

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Discussion Starter · #5 ·
Fuse is good. Battery is good at 12.3 VDC. Keyless entry is transmitting an RF signal. My next step is going to be to take a look at the RF receiver within the car itself, I would assume it is somewhere in the area of the rearview mirrow/ sunroof control area but I may be wrong. Does anyone know the exact location of the receiver?
 

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TIPS:
1. make sure that your car's battery is FULLY recharged since it was discharged to the point of not being able to start the car after the light incident. A battery not fully charged can create situations where some electrical functions won't work as expected.

2. lock you car manually with the key...then walk around to the fuel filler door and see if it is locked. Report back. If the fuel filler door isn't locked...then you need to check the fuse in the trunk (central locking system) and the operation of the fuel filler door actuator. If it is NOT working, it can affect the functioning of the entire central locking system.​

The 315 MHz receiver (frequency used in North America) for the keyless entry (FZV) is located in the C-pillar (passenger side) and the antenna is in the rear windshield (for both style keys):




 

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Discussion Starter · #7 ·
I took the car to Autozone (Not best place for Bimmer, I know) and had them test the battery. Like I said it checked out well at 12.29 VDC and was fully charged. The fuel filler door is locking when I lock the car through the key. I did fail to mention that I had the car checked out a few weeks ago by my mechanic and he ran all codes against the engine.
It came back with a laundry list of electrical squawks, essentially pointing to the battery as the culprit. My mechanic went in to detail and mentioned that if certain systems aren't receiving the 12.3 volts it will start to shut down non-essential items in the car to conserve power and then note them to the on board computer. He asked if I was having electrical issues, I told him I wasn't but asked if I should have the battery replaced he said he wouldn't replace it.
My other theory is the transmitter in the key is not emitting a strong enough signal to trip the central locking system. A replacement is available through my local BMW dealer for $181. I'm really at a loss at this point. I may end up having to take it to my mechanic. As aircraft avionics technician by trade and in school for my electrical engineering degree it's frustrating the hell out of me! Thanks again for all the help, any other advice you have is welcomed and appreciated!
 

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A battery at 12.3 V is only about 1/2 charged. A fully-charged battery will measure 12.6+.

I beileve you have the large all-black key. If so, it has a replaceable Lithium cell inside. Instructions are in your owner's manual.
 

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I'm actually having the same issue, but I did not leave anything on. My keyfob is the diamond one like in the picture, followed the DIY on here and its still not working.
 

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You may need to reinitialize it.
 

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Seek to understand,^Value
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Time to send out the Bat Signal:
Holy bobdmac! Amazingly clever perception!

Note: This is one rare time where I will include the original picture in the quote as it's rather apropos.
 

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Here's a link to a write-up by Jim Cash regarding reinitializing keys for his 97 model, the OP has a 98, so I believe the info should be relevant.

Link: Programming Keys - By Jim Cash

Hope this helps.
 

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Not taking anything away from Jim Cash (he's da man!)...but the procedures to reinitialize all 3 types of keys used during the e39 production has been posted many times...but here they are again. Please follow EVERY instruction to the "T"...don't skip, fudge, combine, or ignore ANY of the steps. :D


2 Button Remote or IR (infrared) Remote:


3 Button (rubber head) Remote:


3 Button (diamond shaped) Remote:

 

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Discussion Starter · #16 ·
Got it! Reprogramming the key worked it's back to it's old self! Thanks again to everyone for all the help/ advice!:thumbup::rofl:
 
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