Removing the Alarm Control unit

[pilot4fn]

Started a new thread with bettern describing name.

Original thread with only couple replys is here: http://986forum.com/forums/boxster-general-discussions/79068-removing-m535.html

I just placed my car (2001 Boxster 2.7 with Manual transmission) in to winter sleep.
There is some issues with key fob remotes not communicating with the M535 unit and it has been verified that key fobs do send good signal. Regardless of the previous, Porsche dealer could not pair the M535 with the key fob remotes.
For the above reasons, I'd like to take the M535 unit out from the car and inspect it if there is water damage etc. If needed to, get unit sent to be repaired.
Before the removal, the plan is to disconnect the battery ground, remove the frunk latch lock 'hook' from the frunk lid.
Should I do something else or take something else in to consideration before removing the M535, so I could install it back later on without too much of grief?

... so have some connection issues between the key fobs and alarm control unit (ACU). Key fobs do send the signal as inspectedby 'Keyfobrepair'. Regardless of this, Porche dealer could not get the connection to work between the key fobs and the car.

I got the ACU out today and Looks like the ACU is fine - does not have any sign of moisture in it. Also the pins on the connectors and plastic box is super clean inside out.

Both, the ACU and fobs were replaced on 2015 by previous owner due to water damage in old unit. So, the current unit looks real good maybe for a good reason.

It is just amazing that the keys do not communicate with the ACU - not even with the attempt by Porsche dealer...
Could there be any other fault possibilities to check before ordering a new fob from Porsche dealer?

[piper6909]

Originally Posted by pilot4fn

Started a new thread with bettern describing name.

Original thread with only couple replys is here: http://986forum.com/forums/boxster-general-discussions/79068-removing-m535.html

I just placed my car (2001 Boxster 2.7 with Manual transmission) in to winter sleep.
There is some issues with key fob remotes not communicating with the M535 unit and it has been verified that key fobs do send good signal. Regardless of the previous, Porsche dealer could not pair the M535 with the key fob remotes.
For the above reasons, I'd like to take the M535 unit out from the car and inspect it if there is water damage etc. If needed to, get unit sent to be repaired.
Before the removal, the plan is to disconnect the battery ground, remove the frunk latch lock 'hook' from the frunk lid.
Should I do something else or take something else in to consideration before removing the M535, so I could install it back later on without too much of grief?

... so have some connection issues between the key fobs and alarm control unit (ACU). Key fobs do send the signal as inspectedby 'Keyfobrepair'. Regardless of this, Porche dealer could not get the connection to work between the key fobs and the car.

I got the ACU out today and Looks like the ACU is fine - does not have any sign of moisture in it. Also the pins on the connectors and plastic box is super clean inside out.

Both, the ACU and fobs were replaced on 2015 by previous owner due to water damage in old unit. So, the current unit looks real good maybe for a good reason.

It is just amazing that the keys do not communicate with the ACU - not even with the attempt by Porsche dealer...
Could there be any other fault possibilities to check before ordering a new fob from Porsche dealer?

When did it stop working?

I believe there's a cable that goes to the antenna. I am not sure if that cable is part of the existing wiring harnesses or separate, as my car was not equipped with remote fobs. If your car was originally equipped with remote key fobs, look for that cable under the seat, and make sure it is connected to the Immobilizer (ACU). If you have it, it connects to the brass connector above the blue connector in your left picture.

If it never worked since you bought it, here's what I suspect may be happening:

If you don't have the antenna cable, then your car was not originally equipped with remote key fobs. It could very well be that your car was not so equipped, and the previous owner may have replaced the original M531 Immobilizer with an upgraded M535 version, and added remote key fobs. Maybe he got them as a package deal. If this is the case, then maybe if you find an antenna and cable from a scrap yard you can get it to work? I don't know for sure though.

[pilot4fn]

Originally Posted by piper6909

When did it stop working?

I believe there's a cable that goes to the antenna. I am not sure if that cable is part of the existing wiring harnesses or separate, as my car was not equipped with remote fobs. If your car was originally equipped with remote key fobs, look for that cable under the seat, and make sure it is connected to the Immobilizer (ACU). If you have it, it connects to the brass connector above the blue connector in your left picture.

If it never worked since you bought it, here's what I suspect may be happening:

If you don't have the antenna cable, then your car was not originally equipped with remote key fobs. It could very well be that your car was not so equipped, and the previous owner may have replaced the original M531 Immobilizer with an upgraded M535 version, and added remote key fobs. Maybe he got them as a package deal. If this is the case, then maybe if you find an antenna and cable from a scrap yard you can get it to work? I don't know for sure though.

Thanks Piper, I have the antenna and I took it off from the ACU, but now when I try to remember of it, there is a chance that the antenna cable could have been better installed in the ACU socket. Hopefully this was the issue... I'll find it out probably on next weekend when I plan to re-install the ACU

[JFP in PA]

Not to be pedantic, but have you checked the fuse in the immobilizer unit?

[pilot4fn]

Originally Posted by JFP in PA

Not to be pedantic, but have you checked the fuse in the immobilizer unit?

A good point thanks - I checked the fuse as soon as I get the ACU out from the car and that was fine.

[Smallblock454]

In general i would say it's the key fobs. Pretty shure there are not a lot of people workshops that are able to decrypt an fsk signal and are able to identify what is wrong with it. The typical cheap key fob testers from china can't do that.

Unfortunately there are a lot of things that can go wrong with thes 9x6 key fobs. Why do i know? Because i offer to repair them: https://986fans.de

Did the Porsche dealer try to learn a new key fob to the alarm control unit?

[pilot4fn]

I was prepared to the idea that I have to get a new key fob from Porsche dealer after I re-install the ACU. Today was the day, and...

Today was rather interesting day - had a chance to disturb buch of my neighbors with a Boxster alarm going off constantly...

Car is 2001 Boxster with manual trasmission.

Battery was disconnected (the ground was not connected). Front trunk lid was open and I did put the ACU back in the car under the seat. Connected the plugs in this order -> blue, black and antenna. All seemed fine for now.

Placed the key in the ingnition and turned it to 1st position.

Connected the battery ground. Interior lights came on immediately BUT the frunk light did NOT come on... it was working fine before I disconnected the battery ground and removed the ACU. The bulb is fine - just tested it.

Tested the frunk lid actuator befoere closing the frunk lid and it worked fine (installed a brand new frunk lid actuator during this summer). Then closed the frunk lid and re-opened fine it with the frunk lid actuator button.

Then closed the drivers door and activated the central lock / alarm. Otherwise all went as normal, but alarm light did not start to flash on top of the dash as usual - alarm indicator light stayed completely non lit, but radio alarm light did stat flashing.

Next I disarmed the alarm / opened the door lock by turnign the key on the door and then opened the door -> this triggered the alarm immediately. The frunk nor trunk did not open anymore and I could not get the car quiet. I waited the alarm to go silent after the 'normal' alarm time. It worked, but it was silent only few seconds untill it started going off again. Turning the key in the ignition did not do anything to help on turnign the alarm off. All lights in the dash lit up as usual when I turned the key, but car did not start nor the engine turn at all as the key was turned to the 'start' position.

Only way for me to get the car quiet was to disconnect the black connector from the ACU.

I'll try to find time next week to open the frunk with the emergency cable in the fenderwell to disconeect the battery.

Do you have any idea what went wrong here... why the alarm started to go off and messed up the ACU re-installation???

I'm lost with this case and prefer not to disturb my neigbors more if anyhow possible. All and any help would be most appreciated.

[piper6909]

Did you say you turned the key to the 1st position and THEN connected the battery? Is this a certain procedure I don't know about?

It seems to me that would be a little dangerous because if you have the key on, if there's any arcing when you connect the battery cable it can seriously harm your electronics. Not saying that's what happened, but I'm curious why you'd do it that way.

I once disconnected my Immobilizer and when I connected it, the car was completely dead. No crank.

I disconnected the ground (with key off) and tapped it against the battery terminal 3 times, then reconnected it. Turned the key on and everything worked! Was it coincidence? I don't know but I remember a guy once told me you can reset the onboard computers that way. I took it with a grain of salt, but when you're desperate you'll try anything and it worked for me.

[pilot4fn]

Originally Posted by piper6909

Did you say you turned the key to the 1st position and THEN connected the battery? Is this a certain procedure I don't know about?

It seems to me that would be a little dangerous because if you have the key on, if there's any arcing when you connect the battery cable it can seriously harm your electronics. Not saying that's what happened, but I'm curious why you'd do it that way.

I once disconnected my Immobilizer and when I connected it, the car was completely dead. No crank.

I disconnected the ground (with key off) and tapped it against the battery terminal 3 times, then reconnected it. Turned the key on and everything worked! Was it coincidence? I don't know but I remember a guy once told me you can reset the onboard computers that way. I took it with a grain of salt, but when you're desperate you'll try anything and it worked for me.

The key in 1st position when the battery terminal is connected is something that I have read of few times on these forums (this one / boxa) to do in order not to get the alarm go off... I have disconnected the battery few times during last 1.5 years and re-connected it like this (key in 1st position) - this has never caused any issues - then again, this was forst time I took the ACU out.
As I get the frunk open, maybe I need to try the trick you mention of tapping the terminal 3 times and then re-connecting the terminal

[piper6909]

Originally Posted by pilot4fn

The key in 1st position when the battery terminal is connected is something that I have read of few times on these forums (this one / boxa) to do in order not to get the alarm go off... I have disconnected the battery few times during last 1.5 years and re-connected it like this (key in 1st position) - this has never caused any issues - then again, this was forst time I took the ACU out.
As I get the frunk open, maybe I need to try the trick you mention of tapping the terminal 3 times and then re-connecting the terminal

wow that's news to me. You're never too old to learn something new!

Good luck!