ToreB

That's interesting yes. The CCU controls this fan. Maybe the CCU somehow react to Scantool's initialisation sequence failing to open communication to the DME.
By the way, when I access the CCU with Scantool, all fans shuts down immediately. I guess that's normal behaviour.

Tore

01coccobet

Hi all,
the walkaround scantool porsche

I did some different setups to try connection to the motronic. And suddenly scantool was connected to it without the workaround (switch installed to the immobilizer unit). So I retried to connect several times and here is my way to connect to the motronic in my '95 cab with remote and immobilizer:

Setup:*
- Car closed and locked.*
- Laptop inside and connected to OBD. Switches to:
- SW1/1 = DME/CCU/ABS/ALARM (not SRS)
- SW2/1 = DME (Motronic)
- Scantool4 not running

1. Press remote control to unlock the door.
2. Open door
3. Put the key into the ignition
4. Ignition on, but do not start the engine
5. Run scantool4.*
6. Scantool4 tries to connect several times but fails.
7. Close scantool4
8. Run scantool4 again
9. Scantool4 tries to connect several times until connection is done. Scantool4 shows all data you need.
Note: If you switch off ignition you have to lock your car and do all this from

I spent 2 hrs sitting on my car yesterday trying a lot of different conditions from the walkaround to everything I could think-about,but didn't work...

only one thing,getting in the ccu,I had :

fault 43 unknown

I have an engine fan always running(don't know which one)but when i connect to ccu ecu,it stops and testing all the ccu items,when i get to

activate item 16 on ccu test outputs,this is it....any clue???

let's keep on trying,I think there will be a solution before the switch...
I'd like to keep my car std... so


tks Sandro

01coccobet

btw my firmware is not 4,but an earlier-one(iirc 1.02)
how do I get the latest?
cheers

techman1

Sandro, my results exactly!

In my earlier research, it appeared a relay in the immobilizer is not energising to pass the k-line signal to the OBD1 socket. In the post from PDriver, he said the relay was not getting a ground signal, or something like that. I believe the Porsche interface tools somehow energise this relay in a way the Scantool does not.

The quoted jumper passes that relay. PDriver said he only bypassed it to run scantool. I wonder what the detriment is of leaving it bypassed all the time?

I also wonder if the DME whizzes like Loren and others with a better understanding could give us some pointers on this relay?

itsdem

Amother run of tests this morning.
The "exoteric" test (see post #17) failed, as I supposed.
Confirmed: Scantool can connect to the all the modules except for the Motronic.
Before trying to install the switch on my immbilizer I want to be sure that no damage will occur to the immobilizer itself.
Can anyone confirm this?
This bypass really works?

techman1

The only confirmation I have seen was the old post from PDriver, who I think lives in Germany.

Still hoping Loren will jump in with help on why this relay on the Immobilizer unit does not seem to engage.

Lorenfb

"why this relay on the Immobilizer unit does not seem to engage."

Once the immobilizer is disarmed via the remote, the K line is connected
thru the immobilizer relay to the W line (DME ECM K line). If this doesn't
occur, the immobilizer can't enable the ECM via its command to run the engine.

techman1

Thanks, Loren!

So, if the Scantool software and USB to OBD interface works properly on a non-immobilizer car, why is it not communicating with the ECU on cars with an immobilizer, even after doing the enable with then remote?
Does the communication with the ECU on a immobilizer equipped car pass through the immobilizer relay and then to the ECU, or is the OBD pin 7 (I think that is right) connect directly to the ECU?


What about this I noticed from post #2. Mojorizing stated:
"The scantool sw uses the scantool.cfg (renamed scantool.txt) file for ecu addresses and baud rate for handshaking - notice for the motronic it's address = 16, baudrate = 9600. The address is sent at 5 baud until the ecu responds at which time the coms speed switches to the baudrate. That's the info on the sw. Make sure your config file is for the 993 - baudrate = 9600 for the 993, 8800 for the 964."
Does the scantool software do the 5 baud thing automatically?

Loren, and all -- Thanks so much for any insight you may have!

Lorenfb

"Does the communication with the ECU on a immobilizer equipped car pass through the immobilizer relay and then to the ECU,"

Yes, it does.

So if the immobilizer is passing the signal, then either the DME ECM address
could be wrong, the baud rate, or the signal levels could be the problem.

techman1

So as to clarify. If I take the wire from pin 7 on the OBD interface, and the K-wire (pin 55 on the DME -diagnosis k-wire) Of course, using all caution to shield the jumper from a short.

If it works, my problem is the signal is not passing thru the Immobilizer.

If it still does not work, I have a problem with the address, baud rate or signal level.