systemsc

The alarm ECU rarely if ever fails, and if it does (complete failure & not intermittent), it's the result of the battery being overcharged or a reversal when jumping the battery.

cobalt

So if they reversed terminals that would fry the alarm ECU? So this is something beyond that. What Module should I approach and can you repair these if they were damaged like this?

cobalt

Recent activity:

Car has been on a tender for 20 hours nearly fully charged. Alarm was silent. No response from the key fob.

I removed the ground battery cable and let stand for 20 Min. Reconnect the cable. Used the key fob and doors locked. light flashing

This time the fob would not unlock the car. I followed the procedure for no working key fob waited 3 min unlock/ lock/unlock within 5 sec yada yada

Alarm sounds and completely locked out. This time I had ear plugs.

The procedure said marker lights will flash but it went right to full alarm mode

I am at a loss.

So I went through my collection of manuals and luckily in box # 1 of 10 I found





I believe they switched out the alarm system in 96 and this is the older OBD system but the newer manuals I have say to use the KTS301 I have with the OBDII port to diagnose the system. Does anyone have an idea if this will use similar protocols for the 96 system and if what similarities. It might be worth tracking down the OBDII cable for my hammer. Note: disclaimer lower right hand corner.

Lorenfb

Yes, I can repair the alarm ECU. I also have stock alarm ECUs. You can send for it testing, at no charge.

Lorenfb

The Bosch Hammer should be able to communicate with the alarm ECU when using the 16 pin adapter cable. You should also be able to communicate will the other ECUs, e.g. CCU, ABS, Air Bag.
Consider doing this before attempting to remove the security cover for the ECM and the immobilizer.

cobalt

So after all these hours I finally was able to get the seat bolts undone without buggering them Although I have them in stock. I really hate when they fight you like that. But these were clearly factory installed

Meanwhile I think it possible a little coffee might be the culprit. Everything is too clean except the alarm module. I don't have the proper cable. All my cars are OBDI round connector I need to source the square one. Apparently it is a cable and just attaches to the unit.

I am guessing once again that coffee killed the alarm system.


Drivers side is quite clean

Passenger not so much I had a similar situation in a 964 where coffee did it. It is all I can think of.

jay@EZimmoblock.com

Has to be something like that. Check both sides of both connectors, too. Let us know what you find.

cobalt

They look clean but I must assume that something made its way into the box. I can try to open it but it isn't mine to mess with. I need to see what the owner wants to do. I could be barking up the wrong tree but it is all I can think of. Nothing computes.

systemsc

Based on the under-seat image, we now know that the DME ECM is an 88 pin OBDII type! So that means that most any generic ODBII scanner should be able to access the ECM's data, that's assuming the immobilizer provides a connection.
It would take a lot of coffee to damage the alarm ECU, given that its circuit has a special sealant and it's mounted horizontally. You can't damage it by carefully opening it.
Just place a rag around it in a vise and carefully use two screwdrivers to pry both sides between the two connectors. The circuit board will easily lift out.

systemsc

With regard to accessing the DME ECM when using a Porsche tester (Hammer/PST2/PIWISI/PIWISII), re-flashing (modifying processor chips) can prevent data access, but not when using a generic OBDII scanner.

jay@EZimmoblock.com

Here's an interesting thread. Apparently the 928 618 260 02 Alarm Unit came with either a green or blue colored sticker - and they don't appear to be the same, functionally, despite identical P/N's. In the thread, 993Brendan's early build 95 came with a GREEN sticker 928 618 260 02 ACU as OE, which had fried. He ordered a used replacement 928 618 260 02 ACU which arrived with a BLUE sticker. When he installed it, all kinds of alarm/door lock hell broke loose. He got a replacement Green sticker part and everything worked fine.

You have a 96 but you have a green sticker 928 618 260 02 ACU. Since this car was recently acquired on BaT, with unknown provenance and a slew of undisclosed problems and shoddy workmanship (reported here ,post 48), is it possible someone swapped in an early, Green sticker ACU to get the thing sold? I keep coming back to the non OEM behaviors you report - being able to silence the alarm with the key (sometimes), the FOB "timing out", etc. Maybe this is what happens when you put an early 95 ACU (for non-immobilized 993's) in an immobilized 96? BTW, i don't know what "FKW" refers to on the ACU label but 993Brendan's original Green label ACU had "42/94" written in which may be week/year of manufacture. The Blue one he tried that didn't work has 28/96 written in. Yours looks like maybe 2/85 or 2/89? if so, no wonder it's going haywire.
Just a thought...

cobalt

The car is just sadly neglected. Everything I touch needs to be repaired or repalced. This is a 95 build but sold as a 96. production date would normally make it a 95.

The one thing I can say about the car is the tub is quite clean and clearly a 58k mile example that was driven hard and put away wet. Gussied up and sold. I have worked on many 964/993's and 911's in general and IMO these seats had never been removed since new. That is why I was hesitant to start drilling. I have uncovered a few things but still working on it.

Everyone here has been of great help. So these are the boxes and things look pretty good but there might be a capacitor issue.


IMMO



Alarm

jay@EZimmoblock.com

Ok not a 96. Still, If immobilized, it's a late 95 so may or may not have used the Blue label ACU. But if the seats haven't been removed what you have is probably OE. Too bad, thought that might have been it.

Can't "see" any obvious problems with the boards and the ACU and connectors look clean and dry.
As for the immo caps - you were getting good range so wouldn't expect any benefit swapping in new caps. But since you have it opened up, wouldn't be a bad idea.

cobalt

I am afraid to touch anything else. There Isn't a thing on this car that doesn't need to be addressed. This is really quite frustrating. I am going to ground the alarm box and install a push button to ground when needed for the time being I don't see what else it can be unless it is ECU related?

systemsc

When Porsche added the immobilizer to the 993, all that was basically different from the 928/964 was how the alarm ECU was armed/disarmed.
The 928/964 armed/disarmed the alarm ECU via the door lock switches, i.e. sending a ground signal to one of two inputs of alarm ECU.
When the immobilizer was added to 993, the door switches were no longer connected to the alarm ECU for arming/disarming.
The immobilizer only provided that function, which is its only function besides controlling access via the OBDII port "K" line to the DME ECM via a "W" line.