I don't have a 993, but the engine in my 911 comes from a 1995 model. I'd like to wire in a diagnostic port for my OBD1 DME, and I am willing to go in and tie into the existing wires. But it would of course be much easier to solder onto the leads that accomplished the task originally.

But I have no idea where the port was/is in a 1995 993. If I knew, I might be able to find where the connections were snipped off. I know I'm going to be looking for keyed power, ground and the K and L diagnostic lines (and I have the pin #s for them), but 90% of the work might already have been done for me.

Anyone know?

 

Jack,

What were you planning on interfacing with the plug? A obd1 reader like durametric or scantool is needed.

 

I've been told I can do either the (hard to find) OBD1 plug, or use the later OBD2 plug.

 

The obd2 plug would be the way to go, get the interface from Tore, who will probably chime in in a moment, and download the scantool software.

There could be a challenge getting the software to work if you have a driveblock DME, but I am betting you bypassed it with a custom chip, so this should be interesting!

 

Jack I'm not certain but it could replicate the earlier '90 -'94 plug ie; round 964 style, I'm receiving a
'95 993 ECU harness in the mail next day or so for an upcoming install with '95 3.6 in my '72 RS .
I'll take a close look it's likely in the exact side console area as the OBD2 receptacle and get back to you, Bert

 

Thanks!

I've heard of people successfully doing it with an OBD2 plug, which gives more reading options.

But my 95 DME does have the early driveblock implementation, which was a pain in the butt when we were first trying to start the thing. A Steve Wong chip fixed that.

 

Thanks for the reference techman1.
It does not matter what plug you use, I would recommend a OBD2-style receptable, it's much easier to find. (eBay) There's really no difference between OBD1 and OBD2. Most people refer to the 19-pin diagnostics connector as OBD1, but this refer to the protocol used in the communication and the functions available in the engine control unit.
The OBD wires you are looking after will be available on the Motronic unit. It is only four wires that are used, the K and L lines, as well as GND and +12V. These are the most important. Some others are also available, such as knock sensor output, speed sensor output and ignition timing output. These are not used by Scantool/T-OBD. The Bosch KTS 301 and maybe other tools have functions that will read these signals.

As far as I know is the wire colours for the above signals the same in all 993 models. K signal is wire colour Orange/White, L wire is Orange/blue. GND (Terminal 31) is Brown, and +12V (Terminal 30) is Red.

I have attached the pinout of the Motronic connector, this maybe is the same as in your car. (I have seen at least a couple of versions) You will find Diagnosis K and L wires there. You will then be able to find the correct wires in your car, connect a OBD connector to these, wiring as this:
L: pin 15
K: pin 7
GND: pin 4 and 5
Terminal 30: pin 16
Hope this helps.
Cheers,
Tore

 

The diagnostic port pigtail comes from the big 14pin connector under the drivers seat it is called X4/2

 

"There's really no difference between OBD1 and OBD2."

With regard to Porsche and the 964/993 ONLY, e.g. generic OBDII scanners
cannot be used on the '95 993 DME ECM even if one has the 16 pin OBDII
connector as was installed on the late '95 993. The 'L' line in ODBII is not
used/needed for DME ECM communications, i.e. only for other ECUs in the 993.

 

Thanks, guys. I'm glad I asked here.

I was already pretty sure I wouldn't be able to get codes with a cheap scanner. But with the port, someone with a Hammer or PST2 should be able to do it.

The plug I got is different than the one ToreB posted. Did I get the wrong one?

 

I believe you have the right connector. Here's a picture of what my OBDII scanner has on the end of it. It looks like it will mate perfectly with your connector.
What data are you looking for? Issue diagnosis, monitoring, or just curious?

 

JackOlsen, your picture show a OBD2 female connector. This is the connector to use, however, the original connector is fixed to the chassis, not hanging on a cable end. Your type seems to be a molded type, you have to make sure that there are wires connected to the pins I have mentioned above.
Cheers,
Tore

 

They probably used it for the instrunments in your car, I think that the X4/2 is the bigger one to the right in the pic


Here it is in a 993