Early Z4 Alarm Siren cross reference

[2003bluez4]

Help needed finding an alarm siren. Working on installing an alarm siren in my 2003 2.5 Z4, mfg date of 7/2003. Problem is it appears like not all bmw sirens work with that year/mfg date. I think it might be that the later sirens included the tilt sensor while the early units did not.

My search shows my z needs alarm horn 65-75-4-115-135. Those are almost impossible to source at a reasonable price. I see lots of alarm horns that use a different bracket but not sure if they will work.

Any help is appreciated. Thanks in advance.

[KevinC]

Yeesh that is expensive for what should be a $10 part. I'd try a wrecker, should be easy to find I'd think?

[Terraphantm]

Maybe E46/E39/E38 siren would work? Part number is different (65758383153), but visually it looks the same.

Otherwise you could probably get the late Z4 part to work with some rewiring

[2003bluez4]

That's what I am looking at as well. Was hoping someone had done this adaptation and could confirm it works.

My research shows that the early z4, mfg between something like 2/2003 and 10/2003 used a siren assembly that did not have a tilt indicator in it where most of them after 10/2003 did. The tilt unit for my 7/2003 car is a separate module. I am not interested in the tilt but rather motion or sound - but I need a siren first

It would seem to me that my car has a four wire plug instead of 6, or at least 4 wires. My thought is that 2 are for power and two are the control lines (like a relay). The later units would then use the extra 2 lines for the tilt sensor mounted in the siren unit. So I think I might be able to make a different work by figuring out the wiring. Sound reasonable??

Thanks, Jim

[Terraphantm]

Pinout for siren alone:
Pin 1 = Ground
Pin 2 = STDWA (Alarm Armed Signal -- this actually comes from the tilt sensor)
Pin 3 = Power (Fuse 30)
Pin 4 = Alarm trigger

Pinout for tilt sensor:
Pin 1 = Tilt signal
Pin 2 = STDWA Out (to interior motion sensor)
Pin 3 = Power (Fuse 30)
Pin 4 = STDWA In (From GM5 module)
Pin 5 = STDWA Out (To Siren Module)

For combined Tilt/Siren:
Pin 1 = STDWA In (From GM5 module)
Pin 2 = Tilt Signal
Pin 3 = STDWA Out (to interior motion sensor)
Pin 4 = Ground
Pin 5 = Siren signal
Pin 6 = Power (Fuse 30)

Electrically what you'd have to do is match up the signals from the tilt sensor to the tilt/siren module, and then add the pin from the siren signal and a ground (on the old tilt sensor, ground is switched via the stdwa pins).

Physically the issue is the tilt sensor on the early E85 is below:



While the siren and combined sensor is in the rear wheel well. So your wiring job would be a bit more extensive.



If it were me, I'd try the E46/E39/E38/E53/E83 siren. Wiring is the same as the Z4 siren. If I had to guess why the part number is different at all, it's probably volume.

[2003bluez4]

Perfect. Thanks so much. I will indeed try the other siren and see if it works as my hunch is the same as yours that it's likely very similar.

Will the siren work by itself without the tilt sensor module (have not sourced it yet) being installed? Could I check it by locking/unlocking the z and hearing the chirp sound? I can turn that option on via coding if it needs it (nod to good old ncs expert ).

Thanks again for the pin outs. Very very useful. Jim

[Terraphantm]

Originally Posted by 2003bluez4

Perfect. Thanks so much. I will indeed try the other siren and see if it works as my hunch is the same as yours that it's likely very similar.

Will the siren work by itself without the tilt sensor module (have not sourced it yet) being installed? Could I check it by locking/unlocking the z and hearing the chirp sound? I can turn that option on via coding if it needs it (nod to good old ncs expert ).

Thanks again for the pin outs. Very very useful. Jim

Never tried. I would probably bridge the STDWA pins to each other (so pins 2, 4, and 5 at the tilt sensor).

[2003bluez4]

Sounds good. I have ordered the siren and also a separate tilt sensor. Once I get them in I will report back as to how it worked.

I am now thinking/looking into the motion sensor. Looks like these fit many years

Jim

[kaybat]

i retrofitted alarms on an 03 and an 06. they were in diff places, the 03 was in the rear fender well,and the 06 was mounted near the rear diff.(had to get it coded on)

I did NOT mount the motion sensor though.good luck

[gpraceman]

I do find it amazing that as expensive as these cars were when new, they did not come with an alarm system. Yet often budget brands would come with one as standard equipment. I had to add the alarm system to my '06 Z4MR. It wasn't a hard install, but I had to buy all of the parts individually (which wasn't cheap). Hardest part was doing the coding to activate it.

[2003bluez4]

The only thing I have found so far in the oem literature is a reference that the Z4 come wired for an alarm! Wow... so nice of them to put the wire in without even the siren.

[2003bluez4]

I have discovered an interesting thing. My Z mfg. date is 7/2003. Anyone before 10/2003 was supposed to have the 4 pin siren with external tilt sensor. Well, not mine. I have the 6 pin wiring connector. I fortunately had both 4 and 6 pin sirens so installed the 6 (totally round with big box bracket) and it worked without even coding it. Chirps with lock and unlock (need to fix that tho). So I am now going by the later instruction set instead of the one for my mfg date. Even the online bmw parts sites show the older squared off 4 pin siren.

Advice to anyone adding the alarm kit(s)- check this plug first to ensure which harness you have in your car.