raycm

Only the DME talks on pin 7. You need to verify your connected to the DME
K line. Ohm meter could be used. Verify that DME output on K line actually
causes RS232 RCV line to toggle. (your circuit board is correct)

For this debug you need to look at The DME's connector under seat.
You could poll DME. Scope DME L line to see it sees poll. Look at DME K
line to see if it is responding. Check voltage level of response. It needs
to go below 1 Volt. If it doesn't increase 3.3K to 10K at collector K line.
Ignition must be on. Engine doesn't need to run.

The shop manual lists some reasons DME wont respond.
It also lists reasons other controllers wont respond.

By the way:
When you change scantool.cfg you should quit scantool app. Modify
scantool.cfg Save change. open scantool. To make sure the app is
not storing the original scantool.cfg and not actually seeing your changes.
It definitely looks at cfg file on starting up.

Ray

cowtown

Those of you looking for a cheap OBD-II connector, I received this one for $10 shipped to my door, and it's fine. No more jumpers into the OBD port....

http://cgi.ebay.com/ebaymotors/ws/eB...tem=4640307575

kevin993c4

I am currently using the rs232 serial cable from my previous purchase at obd-2.com. Upon opening the scantool software, all I saw was the flashing red light trying to connect but couldn't. Is that not the right cable for the job? My goal is also trying to get rid of that annoying airbag light. Thanks.

cowtown

It's got to be a straight-through cable, which is easy to test with your ohmmeter. Beyond that, it may be the computer's port. They are sometimes tricky to set up. Assuming you're running some version of Windows, a few things that I've gotten hung up on in the past are:

-In your BIOS setup (when your PC first boots and you go into the setup screens), the serial port has to be enabled.

-Make sure the serial port maps to COM1 in Windows and that Windows says the port is functioning properly in the device manager.

-I also read that some laptops need to be plugged into AC power for the serial port to work right. That's not the case with my laptop, but sounds like it's worth checking.

-If you have another device like a modem you can plug into, that's a good way to make sure the port's working.

Chris_W

I am getting the same problem as Geldgrube (post 61) DME not responding but ABS, climate etc OK.
Did anyone find a soloution to the problem or do I have to get my scope out?

geldgrube

Hey Chris_W,
before you get your scope out, do you have a late '95 993 and are you havng any problems with your immobilizer? I've done some troubleshooting on my problem and I'm suspecting that my immobilizer may be pulling down the DME signal. My immobilizer light (the one in the clock) has never illuminated and I've determined that I'm not getting the appropriate signal from the immobilizer unit. These two things are telling me that something's up with my immobilizer. I haven't finished troubleshooting yet....it's a bit of a pain to keep taking the seat out to get at the dme & immobilizer! Let me know how you make out.....good luck.

Chris_W

Ron

Yes it's a late 1995 993 that was imported from the USA, the alarm / immobiliser appears to be working OK it arms and disarms correctly and the light in the clock works as it should.

Cheers

Chris

raycm

I measured voltages at OBD connector. Without interface attached.
pin 5 common to:
pin 16 = +12V.
pin 15 = +2.4V
pin 7 = 0.7V
pin 3 = 1.7V

Does your alarm respond?
My alarm will respond with ignition off, or on.
All others need ignition on.
I do not have the elaborate alarm system.
The airbag and alarm do have control signal to the DME.
This are shown connecting to pin 27 of the DME 55 pin connector.
Pin 24 to pin 27 should be +12V with ignition on.

Ray

Chris_W

Hi Ray

The alarm can be accessed via ScanTool although it appears to be continuously connecting and disconnecting every two seconds.

There are no fault codes.

I am away this weekend but will check the voltages on the OBD connector on my return.

Cheers

Chris

raycm

My alarm also continuosly reconnects with no faults recorded.
Only DME sends/rcvs data on OBD-7
DME and others are polled (wakeup) on OBD-15
If climate control, etc work then that leaves only pin 7 as problem.

Ray

PDriver

Hi Geldgrube,
has your car M530 option? Then there is the immobilizer unit installed and
the K-Line from the DME is NOT directly attached to the OBD connector.
The K-Line from the DME is routed to the W-Line Input of the immobilzer unit
and the the K-Line from the immobilizer is routed to the OBD connector.

I have the same problem on my car and the update to the 10k resistor is not
solving the problem. If I shorten the W- and K-Line on the immobilzer I
am able to get a connection with scantool to the DME. So the workaround
is a switch to shorten the two contacts. But I'm search for the real
problem now on the interface...

PDriver

PDriver

Update for geldgrube!
There is a micro signal relais (EA2-6 from NEC) inside the immobilizer,
which is responsible for connecting the incoming K-Line signal from the
motronic to the OBD connector. But the signal for the coil of the relais is
never switching. I think the relais is ok. Because everything else on board
works fine I decided to place a "motronic K-Line" switchover between pin 9
and pin 11 of the immobilizer unit and fix it under the drivers seat.
On next winter there is enough time to do a deeper bug searching...

PDriver

raycm

Thanks, I bought and installed it.
I also recommend this connector.

Ray

raycm

I've revised the scantool.cfg file and the 1st message of this thread. It is worthwhile to replace your scantool.cfg with this new file. The Motronic Inputs and Actual Values are much better. What we need is for one of you to use this tool and then another scan tool. (such as Porsches) Compare the values of each. Report any issues.
Or you can be a sponge and wait for someone else.

The scantool.ini located in C\Windows keeps all the names of the inputs and actual values. It gets large because it just adds names. I deleted the file and let scantool.exe create a new one.

Ray

maurice97C2S

Thanks for all the great work, guys ..

I am in the same position as kevin993c4 - bought the OBD-2 cable / software from Alex Pepper, only to find car was OBD1 with OBD2 connector.

Can I clarify a couple of things - the OBD2 connector view you show in the Rev2 schematic, is that looking at the socket in the car ?

If so, the Pepper cable uses all pins as shown except pin 4 rather than pin 3 - I guess (from your annotation) this pin indicates to the Hammer / PST2 which type of OBD it is dealing with ... therefore would moving that pin in the cable give me an operational cable ? Voltage levels etc should match OBD1 vs OBD2, I imagine.

On the Pepper version, there is a mini pcb inside the serial port connector with a couple of diodes, couple of trannies and an indecipherable 8 pin IC + a few resistors, caps ....so broadly similar component count.

Thanks again, guys !! cheers, Maurice