raycm

Since your having trouble with SRS and DME I'd guess your switches are not the correct type or are wired wrong.

SPDT. ON/NONE/ON. 2 position switches. If you solder these directly to the pcb they will work properly. The pcb labels will be correct.

I put debug instructions in scantool-readme to test the LED's and switches.

Ray

William Green

Ray,

You may have got it right first go, just realised the switches were off - on and not on-off-on.

Order made for new switches and we will see how it goes.

Thanks

brucec59

I'm glad to report that mine works! Woohoo! I still don't have the proper connector for the OBD socket; I soldered 12" long leads to the pcb and pushed the other ends into the socket. And I have yet to put it into a little black box.

It took me a while, but I figured out thru trial and error what the switch positions do:

Switch 1 + Switch 2 = system(s) that connect
L + L = SRS Airbag
L + R = nothing
R + L = ABS/Traction Control, Climate Control, Alarm
R + R = Motronic

NOTE: I soldered toggle switches directly to the pcb. The above L and R refer to the positions of the switch levers, NOT which contacts are connected. When the switch lever is to the left, the middle and right contacts are connected, and visa versa.

My results:

SRS Airbag
2 - Driver ignition circuit to + or 0 V
There were actually two error codes, which I cleared before I wrote them down. The one above code came back after clearing. I'm hoping the airbag light stays off, but I won't know until I drive the car tomorrow.

ABS/Traction Control
No error codes.

Climate Control
24 - Unknown Trouble Code
43 - Unknown Trouble Code
45 - Unknown Trouble Code
Of the above, 24 comes back after clearing.

Alarm
No error codes.

Motronic
No error codes.

A HUGE thank you for everyone who contributed to making this happen, esp. Colin, Ray and Lawrence. I now need to re-read some of those original threads, especially with regard to the software, so I can learn more about what all the actual values and such mean.

Thaddeus

Hey-O,

I had a bum switch. I had the SPDT's from Radio Shack in there, On-Off-On, so I was in despair... but I went ahead and bought 2 new ones, soldered them in, and it all worked.



I can read Motronic, Air Bag, Climate Control, ABS, and Alarm. I CLEARED THE AIRBAG CODE! Woo-hoo! That one operation amortized about half the hard costs of this project.

This is SO COOL!

BTW, I have an unknown error code 45 for the Climate Control... anybody know what that might be?

I am very happy. Thanks to the guys who designed this, and so patiently helped me muddle through it.



And now to write a nasty note to Radio Shack... boneheads... can't even manufacture a SPDT switch without goofin it up...

Thaddeus

Never mind, I found the code in the excellent supporting documentation...
"45=Inside sensor blower motor"... THAT doesn't sound cheap or easy...

Oh well, better to know, right?

jimq

its easy to take the CCU out and clean the dust crap out of the little fan on the back of the unit. Seems like alot of the people using the scantool come up with that error. May or may not be a actual problem. There is a DIY for it in the 964 forum
https://rennlist.com/forums/diy-964-1989-1994-911/211207-how-to-fix-a-squeaky-ccu-fan.html

raycm

I'm sorry there is so much confusion over the switches.
The toggle should have two positions.
One position connects the center to the left and the second position connects the center to the right solder tab. There is no center position of the toggle, bat handle.

If your switch has three positions. You would never use the center position in this interface circuit. Assuming you want the circuit to work.

ON/NONE/ON means no center position.
ON/OFF/ON means the center position causes nothing to be connected.

SPDT. single pole, double throw.
Your 120VAC home light switch would be ON/OFF or ON/NONE/OFF SPST.
i.e. Tabs connected, or tabs disconnected, two tabs.

(I didn't look all this stuff up to be positive about the details, but if everyone follows the logic of switch connections we'll all be happier)

Ray

raycm

I believe your the third person getting unknown trouble code for CCU.
My Trouble Codes.txt file has 2 lists of Climate Control trouble codes.

[H05]
;Climate control trouble codes

and

[H06]
;Climate control trouble codes

You could replace the 05 with 04 or 03. Find out what scantool is looking for.
This number is associated with the serial number.
The CCU returns some number to scantool and it looks that number up in the trouble code list.

I'm assuming you replaced the 964 list with my 993 list. :-)

Ray

William Green

Ray,

Followed your write up to check if everything is working OK.

It all went as detailed with LED's flashing when they should, however, after applying power through the OBD socket in the car, I could not get anything appearing on the laptop screen when a keystroke was made. This makes me think that I have made a mistake in wiring the OBD socket or the DB9 socket.

Can you or anyone point to a link that gives the correct pins to have a wire coming off.

Thanks in advance.

Thaddeus

I fired up the new interface again last night, just to revel in the appearance of 'no trouble codes'.

Martin993

Hi,

does anybody know if raycm's interface/scantool4 does work with a '97 built car, also?
I soldered the interface in a breadboard way and it does echo to hyperterm.
I'm 99 % certain that the hardware works but scantool does try to connect to the car without any sucess. So I tried PDriver's steps to make sure that the immobilizer isn't interfearing.
Does anybody knows how the response looks like on the K-lines when polling with the L-line?
Is there a source that describes the protocol used on the OBD ?

Thanks a lot.
Martin

raycm

https://rennlist.com/forums/993-forum/294027-diy-1995-obd-1-scantool.html
The above link has schematic including pin connections.
Your saying Hyperterminal test doesn't work? You must follow Hyperterminal setup instuctions exactly. This includes a way to make sure Hyperterminal is sending data to the serial port without the interface plugged in.

Ray

JasonAndreas

The ABS, airbag, alarm and climate control units are all exactly the same for all model years of 993. The alarm unit for MY98 is slightly different but should work. I know that the Bosch Hammer software was updated for the MY98 alarm unit and I don't know if the interbyte timing delay used in scantool4 is compatible? The DME control unit in the USA is OBD2 and will not work with Doug's software without some modifications. I'm not sure about ROW? There are some public domain OBD2 software packages that should work with raycm's hardware interface, look for software that supports "Jeff's interface".


On the L-line you send out the control unit id at 5bps (OBD1 DME is 16 and OBD2 is always 33, etc.) and the control unit responds on the K line with eight alternating bits. If you add up the time it takes to receive those bits you'll get the baud rate. If the baud rate is 10400bps the k-line response from an OBD2 control unit will be 55.

The OBD2 protocol used by Porsche is described in the two standards called SAE J1979 and ISO9141-2. The protocol for the non-DME control units (what people are calling OBD1) is described in ISO9141:1989. It is pretty much exactly the same as that used by VagCom. The OBD2 specs can be found online freely available while the OBD1 stuff has to be purchased from ISO for like $40-50USD (it's a whopping 12 pages and not worth the cash). Your name & CC info gets encoded into the PDF which is the reason why you won't find it floating on the net.

Martin993

Thanks a lot for the detailed information JasonAndreas.
I'm going to do some measurements on the interface when hooked up to the car as soon as my wife lets me go :-).

Martin

JEH4278

Are the boards still available? How about either kits of components or assembled boards?