tabasco

Hi,

I have an early 993 (build 02/94) and it has the 19-pin AMP connector.

I bought a scantool interface during the group buy last year and realized I had received a 964 interface (right plug, but no switch).

So we need to modify the 964 interface and add the switch.
If I understand well, the 993 has an extra K' line. On which pin does this K' line go ?

I used the interface as it is, in 964 mode then, and I could connect to everything except the airbag. Does that make sense ? Then why does the switch have 3 positions ? It looked like 2 would be enough.

-Guillaume

tabasco

Bump.

TheOtherEric

AFAIK early 993 with the round 19-pin connector do not have a k' line. To access those functions, you plug your k' wire from your tester into the k line from your car. That works for me. I'm not sure if you can simply connect your tester's k and k' lines together, but maybe.

RicardoD

Guillame,

When you use the scantool are you running the 993 software or the 964 software that came I the CD-R I provided for you?

RicardoD

Based upon the comments from TheOtherEric, in the new unit I send you I can make a connector when you can swap your K and K' pins in the connector. Then there would be no issue of you plugging in the wrong plug into your vehicle.

JasonAndreas

The OBD1 and OBD2 993 both have 2 k-lines and 1 l-line.

tabasco

Thanks Eric,

The interface I have is one of thr group buy, with a nice 19-ping plug. So it won't be easy to change the wire every time.

If everything goes to the same wire, then can't we control that from the software ? There should not be any need for a switch ?
Eric, which interface do you have ?

tabasco

Hi Ricardo,

I ran the 993 software and could connect to everything except the airbag.

Then after you told me the pinout was the same as the 964 I tried the 964 version of the software and it did not connect to anything.

tabasco

That makes sense, if only the plug is different between the early and later 993s...
But I can't find any information about it.
Do you know the pin number for the extra K line (the one that would go to pin3 on the OBD2) ?

In the workshop manual (Section 8, Self Diagnosis) they don't mention an extra K line on the tester.
Just K, L, ground, 12V.

And if Eric can connect to everything using the same wire,
I don't see how he could do that if there were 2 K lines...
Maybe it's not just the plug that is different, maybe there was only
one K line for the early cars, with all the control units on the same "bus" ?

If there are 2 K lines, where does the 2nd one go ?
If there's only one, do I still need a switch on my interface ?

Ricardo, I looked at the post (https://rennlist.com/forums/964-forum/367516-obd1-scantool-interface-group-buy-fully-assembled.html)
where you showed the interface for the group buy.
It has a switch and a 19-pin plug, so exactly what I need.
We can see the OBD3 pin was not connected to the board.
Did this board work ?

RicardoD

Guillame,

The board in the photo was my early prototype to work with my 964, hence the extra K line wasn't hooked up. I have since converted that unit to a 993 model with that K' line hooked up.

I'm surprised you can connect to the other modules even though you have a switchless unit. I'm not an EE so I am not an expert on the schematic. I just executed on RayCM's schematic. Perhaps JasonAndreas understands.

If there are two k-lines on the 19 pin 993 which pin # is the extra K line. Jason, can you help?

19 pin 993:

L = pin 7
K = pin 8
+12v = pin 12
Gnd = pin 10
K' = ???????? does it exist.

Even on RayCM simple instruction sheets which is attached below, it only indicates a single K line on the 19pin version of the 993.

Guillame, I can definitely swap out your unit with a 993 switched version and then give you a 19 pin plug where you can moves the pin around. I have a 19pin plug where I have all the pins holes drilled out. You just have to move the pins to the location you desire, temporarily lock them in place, and the put the backshell back on the connector.

TheOtherEric

Jason, Are you sure that's true for '95 cars with the 19-pin round connector? If so, which of these lines is the k'? Like I said, I'm able to access my k' functions (airbag etc) by plugging my k' wire into the k slot (pin 8). So I wouldn't expect to have a k' line. I've been assuming that this diagram is true for 1995 cars:

tabasco

I was surprised too !
Eric, without swapping pins and on the "Motronic" mode, which modules can you access ? I can access everything except the airbag.

Ricardo, let's wait until we understand exactly what's needed. If there's only 1 K-line, I'm not sure I need a switch !
Maybe the airbag unit can be accessed with a change in software (ideally, the config file !)

Anybody can shed some light on the protocols to wake the different units ?

RicardoD

Guillame,

The switch is there to activate different parts of the circuitry, in particular, the SRS airbag, has its own switch position. So I think you need the switched unit. Look on the CD-R I sent you, in the design-reference folder, there is a PDF of the schematic, there you will see how the 3 position switch has its own configuration just for the SRS airbag.

To be clear, the new plugs I am providing is of my own design where pin changing is very simple. I will post photos later.

tabasco

Just for the sake of information, I spent some time again on this problem I had 18 months ago, and finally fixed it.

I could connect to every module in my car except the airbag.
I have a 964 interface (my car has the round plug but Ricardo made me a 964 version, not 993).
My interface did not have any switch.

The early 993s with the round plug don't have a K' line, only K and L, and to access the airbag a switch is needed so that we can redirect the polling usually done on the L line on the K line. I added one, and now I can access the airbag.

The airbag light was on every time I started the car, since I bought it back in 2003.
I went to the dealership in 2004 or 2005 to have it reset and they told me they could not do it, and the problem was in the clock module itself.
I did not want to spend a few hundred dollars on a new clock so I lived with it.

Connecting to the airbag module with the engine off showed no error code.
With the engine running, the light came on as usual and it gave 2 codes : low battery, and bulb light grounded.
I guess the low battery code was there since the PO used to disconnect the battery all the time (the radio was draining the battery). The grounded bulb was just because the light was on.

2 weeks and one DE later, the airbag light has not come back.

Thanks to all the people on this board that made this possible !