E91 Key Fob not working

wayne1234 · 05-20-2022, 05:08 AM

Morning All,

Sorry if this is the wrong location for this post.

My BMW Key Fob isn't working to unlock / Open the vehicle. Starts perfectly through.

I have to use the master (Mechanical Key to open the car - which sets off the alarm).

Now, I have done a lot of investigation work, which now has me scratching my head :-(

Things I have done.

> All fuses related to the door access are OK.

> Key Fob Battery is reading just over 3v.

Antenna Diversity Unit.

>Pin 1 = 12v

>Pin 2 = 4.5v

> Pin 3 = 4.5v

> Pin 4 = 12v (When Door activated).

These voltages were measured at the antenna - Cover off.

No fault codes relating to the Door Access.

Is there anything I am missing here? I do have full access to ISTA+.

Cheers

P14kle · 05-20-2022, 02:21 PM

Broken wires in loom. Guessing you have a an E91 (Touring)

If so, it will be broken wires in the right hand side rubber gaitor that can be seen when boot hatch is open.

The only remedy is to slice open the rubber boot, and repair the snapped wires and re seal the best you can.

The Saloons E90 can suffer from broken wiring too, but im not sure where the wiring is on those having never owned one.

Do a Search on Google or here for more help. Its a common problem.

Arch Stanton · 05-21-2022, 04:43 PM

could also be the diversity module in the rear spoiler, water gets in there and corrodes them even though look ok. they ar easy enough to get at and they open up easy enough to check for corrosion

michaelalex17 · 05-22-2022, 04:23 PM

Quote:

Originally Posted by P14kle

Broken wires in loom. Guessing you have a an E91 (Touring)

If so, it will be broken wires in the right hand side rubber gaitor that can be seen when boot hatch is open.

The only remedy is to slice open the rubber boot, and repair the snapped wires and re seal the best you can.

The Saloons E90 can suffer from broken wiring too, but im not sure where the wiring is on those having never owned one.

Do a Search on Google or here for more help. Its a common problem.

This was my exact problem as well

Runnin'Rich · 05-23-2022, 12:40 AM

Don't slice open the rubber!

Simple pull it away from the body side and slide it down the wires to expose the damaged section. Repair the damaged section and slide it back

Runnin'Rich · 05-23-2022, 01:06 AM

Does the lock/unlock button work on the dashboard?

You're voltages are in-line with a good working unit, but maybe your module is still bad?

Definitely worth checking the wires

DCD_F80M3 · 06-07-2022, 05:40 PM

Wiring harness is a good place to start.
If you have access to ISTA, you should be able to check to see if a valid lock/unlock signal is being received.

05-20-2022, 05:08 AM	#1
wayne1234 New Member 2 Rep 12 Posts Drives: E91 Join Date: Oct 2019 Location: Wales iTrader: (0)	E91 Key Fob not working - Tried Everything HELP!! Morning All, Sorry if this is the wrong location for this post. My BMW Key Fob isn't working to unlock / Open the vehicle. Starts perfectly through. I have to use the master (Mechanical Key to open the car - which sets off the alarm). Now, I have done a lot of investigation work, which now has me scratching my head :-( Things I have done. > All fuses related to the door access are OK. > Key Fob Battery is reading just over 3v. Antenna Diversity Unit. >Pin 1 = 12v >Pin 2 = 4.5v > Pin 3 = 4.5v > Pin 4 = 12v (When Door activated). These voltages were measured at the antenna - Cover off. No fault codes relating to the Door Access. Is there anything I am missing here? I do have full access to ISTA+. Cheers
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05-20-2022, 02:21 PM	#2
P14kle Second Lieutenant 215 Rep 299 Posts Drives: E91 Join Date: Dec 2015 Location: South West UK iTrader: (0)	Broken wires in loom. Guessing you have a an E91 (Touring) If so, it will be broken wires in the right hand side rubber gaitor that can be seen when boot hatch is open. The only remedy is to slice open the rubber boot, and repair the snapped wires and re seal the best you can. The Saloons E90 can suffer from broken wiring too, but im not sure where the wiring is on those having never owned one. Do a Search on Google or here for more help. Its a common problem.
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05-21-2022, 04:43 PM	#3
Arch Stanton Second Lieutenant 49 Rep 256 Posts Drives: BMW 335i touring Join Date: Aug 2009 Location: the smelly bit of the north iTrader: (0)	could also be the diversity module in the rear spoiler, water gets in there and corrodes them even though look ok. they ar easy enough to get at and they open up easy enough to check for corrosion
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05-23-2022, 12:40 AM	#5
Runnin'Rich Second Lieutenant 139 Rep 208 Posts Drives: 2009MY E91 328Xi 6MT Join Date: Sep 2020 Location: British Columbia Canada iTrader: (0)	Don't slice open the rubber! Simple pull it away from the body side and slide it down the wires to expose the damaged section. Repair the damaged section and slide it back
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05-23-2022, 01:06 AM	#6
Runnin'Rich Second Lieutenant 139 Rep 208 Posts Drives: 2009MY E91 328Xi 6MT Join Date: Sep 2020 Location: British Columbia Canada iTrader: (0)	Does the lock/unlock button work on the dashboard? You're voltages are in-line with a good working unit, but maybe your module is still bad? Definitely worth checking the wires
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06-07-2022, 05:40 PM	#7
DCD_F80M3 Registered 3 Rep 4 Posts Drives: BMW M3 Join Date: May 2022 Location: UK iTrader: (0)	Wiring harness is a good place to start. If you have access to ISTA, you should be able to check to see if a valid lock/unlock signal is being received.
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