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Discussion Starter · #1 · (Edited)
E36 & E34 Alarm Identification & Faults Guide - GR40, 2T, 3T, 3G EWS

BMW E32, E34 & E36 Immobiliser and Alarm Identification & Faults Guide - GR40, 2T, 3T, 3G EWS (Sigma, Gemel, Serpi Star) EWS I, EWS II

My aim is to post all the confirmed knowledge about the immobiliser and alarm systems listed above. Many thanks to all those that have given me updates.

NOTE: There is a lot of info here so please take the time to read it carefully. If you have read the guide and still can't work out what to do then post a question in the auto electrical part of the forum mentioning that you have read the guide. Please don't add questions to the end of the guide or PM me as our private message won't help others.

If you don’t have a BMW “branded” alarm but need help then your best bet is to try a dedicated alarm forum.

Do I Have an Immobiliser? - All E34s and E36s after Sept 1993 came with a factory fitted immobiliser system. There were three types, Drive Away Protection, EWS I and EWS II. Check the sticker on the front suspension turret under the bonnet to find your manufacture date.

Drive Away Protection: 9/93 to 12/93 - The Injection/Ignition systems are disabled if the car is "Double Locked"

EWS is BMW's "Electronische Wegfahrsperre" or Electronic Immobiliser". There were two versions of EWS used on the E34 and E36...

EWS I: 1/94 to 1/95 - Improved on the Drive Away Protection by adding a starter immobilisation circuit.

EWS II: 1/95 to end of production - Improved on EWS I by adding the Key Chip and Transponder to the immobiliser circuit. New ignition keys can be bought from the dealer pre-cut and pre-programmed for £30 plus, depending on the type. You'll need to take the V5 in your name plus some ID. Expect to wait around a week.

You can also use the CODE button of the 18 button On-Board Computer (OBC) if fitted, as additional protection with any of these systems.

The EWS Technical guide can be downloaded here...

If you are experiencing starting problems and it seems like the immobiliser is activated there are a few things you can check, however if the car turns over it is not the immobiliser as the starter system is disabled when EWS I and II are activated...

1) Early E36s have a starter immobilisation relay and this can wear out
2) Also on early E36s there is an issue with poor scuttle drainage which leads to flooding of the DME (ECU) compartment, see here...

3) All the immobiliser systems above work on a double lock/unlock signal from the driver or passenger door or a signal that mimics this from the alarm. It's always worth trying to lock & unlock the car from the passenger side (less wear on the lock) to see if it allows the car to start.
4) EWS II keys can get damaged and the chip is not be recognised by the EWS system. Try another key to see if this cures the issue. Even the grey valet key and small emergency key have chips in them.
5) Also check No.3 in the alarm faults below - bootlid wiring.

What Alarm System Do I Have? - If you don’t have a fob the easy way to identify your alarm is to find the siren or the alarm module. Generally, most BMW E36 & E34 alarms were were dealer retrofit (apart from "National Versions" see below) and were made by Sigma (part of the Gemel group). Because of this the module and siren location can vary from car to car.

In the E36 the alarm module is usually in one of three places
1) Behind glovebox in the top slot of the module carrier (most common location)
2) Under the carpet in the passenger footwell (this is a bad location as it can become damp) See here... (4th post)
3) Under the steering wheel in the module carrier (This is more common when the system has been fitted to a pre 96 car)

In the E34 it can usually be found under the rear seat.

The siren is usually in one of three places
1) Nearside (passenger side) inner wing (most common location)
2) Offside (driver side) inner wing
3) Bulkhead near the fuse box (320/325/323/328 only)

I can't find the siren or the module! - You need to check if there is a red LED button by the gearstick and movement sensors at the top of the windscreen pillars (not on Convertible). If you don't have these either then its likely you never had an alarm fitted.

Radio Remote Control (Central Locking) - Some models had factory fit remote central locking on the key, BMW call this their Radio Remote Control (RRC) system. If you need a replacement key and your car has EWS II you'll need to get one from the dealer as above. You'll still need to re-sync the central locking to the remote yourself here...

"National Version" Alarm Systems - In various countries (except the USA) BMW included the option of an alarm system as a factory fit. This system is linked directly to the RRC system above, the obvious difference being the flush fit LED next to the gear selector. Another way to check is if you have a large chrome topped micro switch on the O/S/F inner wing, just near the washer bottle. This system arms and disarms through the RRC three button key and works in a similar way to the 3G systems, in that it sends a double lock pulse to set the immobiliser and monitors the door / boot / bonnet sensors for intrusion. I have not seen a version of this system with motion sensors but am happy to be corrected. The siren is located inside the O/S/F wing behind the inner wheel arch cover underneath the washer bottle. This system seems to be pretty reliable with the only reported issue being some over-sensitivity to voltage drop with cars that have an old battery.

GR40 (also known as Anti-Theft System 3) - This system was used on both the E34 and E36 from around 1990 to 1992 and uses a static code. The two button fob can be programmed by following the instructions here... The siren is almost identical to the 3G (Mk1). Fobs turn up regularly on eBay for around £10.

2T & 3T - These systems used on the E36 & E34 up to 1996 and have a static code. The 2T is an alarm only but the 3T is also an immobiliser. Both systems use the single button black or grey "Domino" type AC38 type fob that can only be programmed by a BMW Dealer/BMW Independent/Sigma Alarm Agent or you can buy your own programmer. Both siren types are clearly identifiable by a sticker. Fobs turn up regularly on eBay for around £10. A similar system that uses the same fob is fitted to some Subaru & Renault models and can be programmed via a plug-in keypad - This doesn't work with the BMW version as the Sigma programmer works by communicating with the module via the LED.

The 2T and 3T are not very user friendly so many replace them with 3G Mk2 or an aftermarket system. Provided the alarm is unset then it can be removed by simply cutting it out, see here...

User Guide (1995) is here... 1995/

3G Mk1 (sometimes known as 3C) – This system was used on the E34 & E36 up to 1996 and uses a static code The black "missing corner" single button fob is only user programmable with some difficulty. You’ll need a working fob, then you need to solder and de-solder connections on the new fob circuit to match as follows (thanks to

You will need…

A working (or known to have worked) fob to copy
A replacement fob to re-programme
A decent thin tip soldering iron, solder & flux
A de-soldering tool or de-soldering braid

Open the fob and turn it over so you can see the circuit board. There is an array of 3 x 7 solder pads (see red box in the photo).

The upper and lower rows determine the 'code' for the key fob. The pads either have a blob of solder joining them, or no solder at all. You need to replicate this pattern in your replacement fob using the 4 step re-programming example sequence below.

1) The yellow dots show the code pattern for your working fob
2) The orange dots show the code pattern for your new fob pattern
3) De-solder the orange dots in the wrong position, removing all traces of solder
4) Re-solder the missing dots to match the working fob

Re-assemble the fob, replace the battery (right way round) and test. If you have made a good job of your de-soldering and soldering all should be well.

The other option is programming by a BMW Dealer/BMW Independent/Sigma Alarm Agent. Only one siren type was used (see below). Fobs turn up regularly on eBay for around £10.

The alarm module comes in two parts. The module (the large bit) and the remote receiver (the small bit).

Those familiar with the 3G Mk2 below will note that the module is identical except for the absence of the coding switch. It is possible to upgrade the 3G Mk1 to a 3G Mk2 by replacing the entire module or just the remote receiver part but you need to check the wiring is identical.

For both the above systems you may have read articles on the web that state you can program the alarm by opening the boot, closing the door, turning the ignition on 5 times, etc. These instructions are for the USA spec alarm made by Alpine and apart from giving your neighbours a laugh they won’t do anything in UK spec cars regardless of the system you have.

3G Mk2 This Thatcham Cat 1 system came in when the E36 was facelifted in 1996 and uses a rolling code. I've not seen it used on an E34 but I'm happy to be corrected. The two button (grey & red) "missing corner" fobs can be easily user reprogrammed (see below).

Fobs turn up regularly on eBay for around £10 to £15, but be cautious as there are two identical types, one of which is not compatible, see here... Replacement cases can be bought for £10 upwards.

The volume and number of beeps the system makes when setting & unsetting can only be programmed by a dealer or Sigma specialist.

If your fob doesn’t work check the battery first. If the LED on the fob flashes instead of being constant then the battery is on the way out. When you replace the battery clean the contacts as they get coated in a “varnish” of dried sweat and dust. The battery should be inserted positive to left, negative to right. If the battery is good and the fob LED lights up but still does nothing then it probably needs reprogramming by following these instructions (I’ll assume you have located the alarm module already)

1) Prise out the rubber bung from the remote receiver.
2) Insert a thin screwdriver into the hole and flick the coding switch to the right to set the remote receiver into “program” mode.
3) Press the red button once on each remote (max 4 remotes).
4) Flick the coding switch back to the left and replace the rubber bung.Your fobs should now work.

If there still seems to be a problem prise the remote receiver off the control unit to reset it. When you replace it (be careful you don’t bend the pins) the central locking should close & open. Re-code your fob as in steps 1 to 4.

If this doesn't work fully unplug the module, wait a minute, then reconnect it and Re-code your fob as in steps 1 to 4.

Still no joy? Prise the remote receiver off, short pins 1 & 6, then pins 1 & 8, reconnect the receiver, then Re-code your fob as in steps 1 to 4.

Finally, if all else fails prise the remote reciever off, short all the pins in the module, then Re-code your fob as in steps 1 to 4.

If that doesn't work then you need a new receiver.

User Guide (1995) is here... V8 1995/
User Guide (1998) is here... V11 1998/

There also appears to be an early version of this system that has the Mk2 fobs but the remote receiver doesn't have a coding switch. If you dismantle the module you should find an orange wire. Grounding this wire to earth seems to have the same effect as flicking the coding switch, after which you follow the coding instructions as above.

Alarm Faults

If your alarm activates for no reason there are a few common faults you can look for...

1) Bonnet Pin - On older models the bonnet pin was slightly shallower so that when the bonnet was hot the pin no longer made contact due to expansion. A modified longer pin was fitted to later cars.

2) Movement Sensors - Some times these just fail and trigger false alarms. You can test this by unplugging them from the module.

3) Wiring - As the alarm is connected to the central locking system sometimes it appears to malfunction when in fact it is a wiring problem elsewhere. Most common is the wires that run from the body to the boot/tailgate through the rubber tube, see here...!?highlight=318is+coupe+bootlid In addition the central locking system has earths in the passenger side footwell which is prone to damp and water ingress. Make sure you check this area too as corroded earths will give similar symptoms.

4) Siren Faults - If your siren exhibits any of the following symptoms (not 2T)…

  • No "beep" on arm & disarm
  • Indicators flashing for 30 seconds to indicate a fault
  • Random "squeaking" or "crackling" of the siren
  • No sound from the siren (apart from when switched off!)
...then it is likely that the back-up battery is failing or the inside of the siren is damp and corrosion has taken hold. These symptoms usually occur after the car battery has been discharged. If the backup battery is decent it may take a few days to recharge itself and all will be well, if not then you may need to replace it. Unfortunately direct replacements backup batteries don't seem to be available anymore but you can replace it with any rechargeable battery of the correct voltage and dimensions.

5) Low battery voltage - Most of the BMW alarm systems, including the "National Version" systems have a voltage check feature which measures the voltage at set against current voltage. If you have a battery at low charge or your car has a "drain" possibly caused by the boot wiring, then the voltage will drop over time and at some time after "set" the voltage will drop and system will activate. Remedy is to source the battery drain or to replace the failing battery.

GR40 - See 3G Mk1

2T - This is a basic siren without a key-switch. It doesn't have a backup battery.

3T - This is a basic siren without a key-switch. It has a 9.6V backup battery that can be replaced.

3G Mk1 - This is a large siren with a key-switch to override the alarm. It has a 7.2V backup battery that can be replaced.

3G Mk2 - This is a smaller siren and comes without a key-switch (Standard Siren) or with a key-switch (Emergency Current Siren). The difference is that the Emergency Current Siren monitors the electrical system and triggers the alarm if the power drops or is cut. All the components are sealed in resin and it cannot be dismantled. This is a security feature that will allow the siren to continue sounding even if you cut the wires or try to smash it.

Good Luck!



1,824 Posts
Very good guide!

2T – This system was also used on the E34 up to 1996 and uses a static code. It is only user programmable with some difficulty. You’ll need a working fob, then you need to solder and de-solder connections on the new fob circuit to match. The other option is programming by a BMW Dealer/BMW Independent/Sigma Alarm Agent. Only one siren type was used. Fobs turn up regularly on eBay for around £5 to £10.

The alarm module comes in two parts. The control unit (the large bit) and the remote receiver (the small bit).

Those familiar with the 3G system below will note that it is identical except for the absence of the coding switch. In theory it is possible to upgrade the 2T to a 3G by replacing the entire module or just the remote receiver part. If anyone has done this please let us know!

For both the above systems you may have read articles on the web that state you can reprogram the alarm by opening the boot, closing the door, turning the ignition on 5 times, etc. These instructions are for the USA spec alarm made by Alpine and apart from giving your neighbours a laugh they won’t do anything else.
My 94 e36 has this 2T alarm, the only reason I know is becuase the module behind the glovebox is the same as your 2T module picture. I bought the car with no remote fobs however I did find a fob in a breakers yard car, again like the 1 button fob you have pictures.
Is there any way to tell how the pins should be soldered just by the numbers on the module?

Again, VERY helpful guide! It took me forever to figure out what kind of fob my car should have come with but this sums it up perfectly.

5 Posts
I have a Sigma 2T alarm in my 1996 E36. It looks identical to the 3T alarm you've pictured (except it says 2T) and uses an AC38 fob. I know it's a 2T system as it says it on the control module. I also only have one module and not a seperate receiver module.
I was under the impression the 2T was just and alarm and the 3T was also an immobiliser and this unit was phased out with the introduction of EWS in 1995.

222 Posts
A handy tip I don't see mentioned often for the 3G fob is this -

If you've bought a second hand remote, change the battery *before* syncing it to the car. Saves having to remove the glovebox and do it all over again if you do it later, as when you remove the battery, it more often than not loses sync with the car. ;) :lol

(And yes, I learned that one from experience! I can now remove an E36 glovebox in about one minute :rofl )

165 Posts
Hi and well done on a great guide. I have the 3g type with a very loud beep and beep beep when i set it. Well, at 4am it sounds very loud. Do you know if its possible to switch the beeps off? Thanks.

2,493 Posts
Discussion Starter · #11 ·

This forum is really about guides so the only posts here should be to add info.

If you need help please post your questions in the auto-electrical forum and we'll try and help you there.


359 Posts
Very useful guide. How easy would you say it is to remove an alarm system from a scrap car and put it in my own?

1 Posts
Soldering/Programming Fob without alarm

Thanks for the helpful info here! I just got my alarm (single button) working by soldering the fob, without having another fob to refer to. You can work out the code from the module on the receiver. Here's a quick guide:
- There's a module that lifts off the alarm unit in the glovebox, take that out and open it up. There's a board inside.
- On that board you should see a set of pads similar to the ones in the key fob. There are 18 pads total on both (there are 4 more on the remote, above and left in the photo). By pad I mean the pair of half circle shapes, some of which will be bridged with solder.
- Pads on the receiver are in 4 rows, the first two as I look at it have 5 pads, then 4 pads on the next two. I numbered them as follows:
VSS 1   2   3   4   5
    A1  A2  A3  A4  A5
VDD 6   7   8   9   10
VDD     11  12  13  14
        A6  A7  A8  A9
VSS     15  16  17  18
A1 through A9 are pins on the control chips, you can ignore that, the important part is the numbers, which you should see correspond to the position of pads on the board

(For the electronically minded pads set tri-state address lines to the decoder chip, hence the A1-A9. All the Vss/Vdd lines are tied together)

- Pads on the remote are as follows (Upside down compared to the earlier photo):
VSS 1   2   3   4  5  15 16
    A1  A2  A3  A4 A5 A6 A7
VDD 6   7   8   9  10 11 12
VDD                   14 13
                      A9 A8
VSS                   18 17
I've labelled it so that pad numbers correspond between the remote and receiver. All you need to do is match the remote codes to the receiver codes. I altered the remote because I didn't want to risk breaking the alarm module.

Plug the module back onto your alarm and the remote should be working. If not check you haven't got any stray solder bridges on the remote. Hope this works for someone!

30 Posts
My new 1998 318i Touring has a 3G Alarm fitted but was sold without the fob. The siren was turned off and when I removed the glovebox the module was unplugged. I don't know how long it had been like that, I guess the fob was lost sometime in the past 12 years and the alarm has therefore been unused. I bought a brand new fob from BMW Exeter for £40 + VAT (couldn't find any on ebay) and followed the proceedure to re-programme the fob. However when I reconnected the module tha alarm went off indicating it was armed and would not accept the new fob. After looking at various forums I found the answer:

1) After 30 seconds the alarm goes quite, shut the door.
2) Unplug the receiver and short pins 5 & 6 (pin 8 being the outermost pin) this locks the central locking.
3) Short pins 4 & 6 unlocking the central locking and disarming the alarm.
4) Now follow the re-programming proceedure so the receiver accepts the new fob.

I hope this helps anyone who has bought a BMW with a 3G alarm but doesn't have a fob.

24 Posts
318IS Coupe 1996 - I am pretty sure the alarm is a 3T it has a AC38 fob, The siren does not work but the lights flash when the alarm is activated. We only have one falling to pieces FOB, is there any easy way to remove the alarm/imobolizer? I dont seem to be able to get it into valet mode?

It says in the original post that when the alarm is deactivated it can be removed/replaced? is it a simple unplug/switch off or does the whole loom need rewiring? removing all the black wires? I am sure it is a 3T as we have already followed the manual to disable the EWS imobolizer and the car only starts after the alarm has been deactivated?

Any help will be brilliant I dont want to spend £100 on a new fob and someone programming it, and I dont want to spend £100 on someone trying to remove the alarm system, and possibly having our car out of action for days.


6 Posts
3G Alarm module removal problems

Hi all, My 1997 328i coupe which I use for track days only kept draining its battery, so I decided to remove some unnecessary items and make her a bit lighter at the same time.
Like an idiot who doesn't really know what he is doing, I removed the ALARM MODULE, (thinking it was something to do with the bluetooth phone kit), and then my wife then tidied up and threw it away! I believe it was the 3G Version 2.
What I would ideally like to do is remove the alarm system completely. As trying to get it all working again sounds like a nightmare!
Can anyone help and tell me what else I need to remove or bypass?
Any help at all would be great! Cheers!!
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