Really

Well guys,

I don't know what genius decided to put my 2003 986's ECU "immobilizer" board in a water bowl underneath the seat in a convertible, but the inevitable has happened and the thing has gotten water damage.

I'm looking at an 1800$ repair, but before I bite the bullet I have pulled the board, cleaned off all corrosion with 100% IPA and a soft bristle brush, left the unit overnight in a vacuum dessicator, and reinstalled it.

Auxilliary lights and dash come on, alarm system works and went off when I jarred the seat back into place, but nothing happens when I turn the key in the ignition.

My question is this - assuming the best case scenario that cleaning the corrosion off the board works - is there anything more I need to do after reinstalling the unit to start the vehicle? Clearing fault codes, etc to reset the immobilizer? Or would it otherwise be working now, if the board was still any good?

Thanks!

Macster

By "nothing happens" when you turn the key in the ignition, what exactly do you mean? No dash lights? Or Dash lights but the engine doesn't crank? Or something else?

If the dash lights come on and other electrical systems appear to work but the engine doesn't crank if the car is equipped with a manual transmission this can be the clutch safety interlock switch.

If a Tip it may be the engine controller doesn't recognize the gear selector is in Park.

It could be possible the ignition switch is at fault but generally a bad switch does not only restrict itself to just the engine failing to crank.

Another explanation is when the key is turned the RFID from the pill in the key module is not making it to the security module. If this occurs the security module can't of course recognize the RFID and won't permit the engine starter to engage.

There are a number of possible failure points: The antenna behind the ignition key surround is broken, but if you haven't been under the dash, messing around the ignition switch the antenna should be ok.

The RFID pill could be bad. You can try another key.

Or the RF signal that is beamed to the key module and its RFID pill is not being sent. Or the RF signal from the RFID pill is being sent but it is no making it to the security module. Or the signal RFID signal is being sent and decoded but the RFID is not in the security module's non-volatile memory list of recognized RFIDs.

Given the security module was exposed to water I favor -- so to speak -- the RF signal is not being sent or the response is not being received. It is unlikely something could have occurred to erase/garble the RFID stored in the security module's non volatile memory.

A Porsche diagnostics computer or I believe a Durametric tool can retrieve any security system errors.

Be sure you address how the water got in the cabin. Check the front and back water drains for any blockages. Check along the door bottoms for any signs of dampness. Give the doors a shaking checking for any water in the doors. If the door membrane fails water gets into the dry side and this will play havoc with the door lock and window electrics and at some point affect the car's security system.

There is no reset of the security module, other than what occurs when the unit loses power. Hopefully before you worked on it you disconnected the battery and the unit should have come up from a no power state.

If you want find the fuse (or fuses) that power the security module -- and probably power other circuits too -- and pull the fuse(s). Or just disconnect the battery for a while. Be sure all electrical systems are off, the key is removed from the ignition, etc. As much as I am reluctant to mess with the battery I think I would prefer the battery disconnect method of power resetting the car's electrical system.

Be sure to follow the owners manual guidelines regarding battery disconnect/reconnect. Be very careful when reconnecting the battery to not reverse the connections.

You want to be sure a full power off/power on reset is done to give the security module every chance to resume correct operation.

bekks

Worst case should be a little better than $1800. I just did a new immobilizer with two new fobs for about $1400 CAD.

Macster

Well, a new immobilizer and two new fobs (with new RFIDs) is certainly one way to address the no start issue. To be sure a bit pricey a way but my inclination would be if the immobilizer got wet in my car to play it safe and just buy a new one.

It is unfortunate the immobilizer is where it is but it is where it is so an owner needs to be on his toes regarding possible water in the cabin.

So be *darn* sure the cabin is dry everywhere, there is no lingering moisture in the carpets. Be sure you ID how the water got in the cabin and address this problem. Remember there is always 2 ways the water got in the cabin unless there was just one way or 3 or more ways...

Really

Thanks for the replies. The convertible top isn't water-tight in the back where it has come a bit loose. The rain accumulates there where the canvas has curled and drains in. Of course, I keep a car cover on it, but we've had some storms come thru that have blown it off. And there's been record breaking rainfall this year where I live, I swear we can't get 5 dry days in a row. I've ordered a water-tight box for the ECU from a company called ECU doctors, and hopefully that 150$ investment will prevent the problem from recurring. Dealership rep told me it's 1100$ just for the M535 unit, not including the key fobs and labor.

bekks

Your dealership is robbing you. It was under $700 CAD for the immobilizer from my local dealership. Sounds like you may have some functionality still in your unit so they may be able to get the key information from it and then transfer that to a new unit meaning you don't need new fobs.

Macster

I know nothing of the water tight box to protect the ECU (actually the ECU is located on the bulk head wall at in the rear trunk, maybe you are thinking of the security module under the seat on the floor of the cabin?) but that's a band aid. While it might keep the security module dry water in the cabin is still not something I'd like. Soggy carpet. The interior will begin to smell.

If the top is leaking you need to seriously consider replacing the top.

My Boxster's top finally developed a leak about in the center of the top just ahead of the rear window. The window seam itself was not leaking the top was. I don't recall the exact date but roughly around 3 years ago I had a GAHH top installed. Total price came to around $1400. Depending upon where you are you might get this done for less. (In CA everything costs way more.)

I stuck with the plastic rear window cause I like the shape of the top and the large rear window and the fact that putting the top into the service position is not affected one bit.

The GAHH top appeared to be well made, took all the various hardware the stock top had to contribute, and the 2 years I owned the car after the new top was installed the top was just fine.

Really

Well, in the end the dealership was able to get the price down to about 1500 USD for the replacement M535 unit, reprogramming, and a new key fob. However, now that I've driven the car about 50 miles or so I see that it has more problems. Immediately after getting the car back, I noticed that you need to pull the driver's door handle on the inside of the car TWICE before the door will open. The first pull just adjusts the window. Also, the driver's side window button now must be held down to adjust instead of pressing the button a single time. Also, I drove it to work and it gave me a tiptronic emergency run warning, drove it home with the warning and the next morning the battery was dead. Fun times.

Macster

IIRC having to pull the inside door handle twice is required if the car is locked.

If you are not locking the car then perhaps it is locking itself?

My car did this. What happened with my car is the car would self lock once in a while right after engine start or shortly thereafter. I could discern no other pattern. I'd hear the door locks engage and concurrent with this the red LED in the door lock button would light up. Sometimes after I'd reach up and manually unlock the car it would self lock again.

Now it is possible the car is not locking itself due to some problem. I never really bothered to check into this because it was not a feature I wanted enabled for my Boxster but it may be possible to configure the car's security system to automatically lock the doors when the car begins to move. (Certainly other cars I have owned/currently own do this.)

This door locking automatically is part of the "KOMFORT" bus stuff. And the window behavior might also be a KOMFORT bus thing. My windows were configured to work with one touch to lower or raise.

There was other weirdness with the passenger window. Failing to drop when the door handle was pulled or worse dropping only to go back up again shortly after the door was opened.

Weirdness from the doors or windows can be a sign of water in the doors. In my car's case though it proved to not be due to water in the doors but a bad door lock controller. This is a pretty large box with a good assortment of hardware (mainly outside) and electronics (inside). The tech tore into the door and did some tests and confirmed it was the door lock controller and not one of the other switches or mechanical linkages in the door.

The Tip error could have been the Tip reacting to low voltage due to a bad battery or weak alternator output. But of course if there is water in the doors or a door lock controller has gone bad this can cause a power drain even with the engine off and the car locked.