aribop

specifically the one that shows the connections for the OBDII port on the later model 993.
Thanks!
Albert

IXLR8

Some info I saved some time ago, just in case.

I don't know if this is for the OBD I 993s with the OBD II connector or for the 1996 and up OBD II 993s though.

aribop

Thanks, Alex! This is a good start. I am also looking for the diagram of where these wires connect to.

geolab

this is not 993 specific, this is the universal layout.

layout for OBDI and OBDII porsche specific plug connections, is the same
you read an OBDI and OBDII 993 with the same cable

In ROW cars, the round OBDI cable was for 964's and not common on 993 whilst all 993's are OBDI et le turbo is OBDII
regards

IXLR8

Just to confirm then, both OBD I and OBD II systems, although they use the same OBD II connector on later 1995 993s, have the same data lines as well as power, ground, etc?


I thought the round 19 pin connector was found in the early 993s as well. I think the changeover to the OBD II connector was sometime during the '95 model year.

IXLR8

Albert, got your PM and comment on the connector.

This should be what you have...

aribop

Thanks for the info!

geolab

1 - hot
2 + 6 - hot (same signal)
3 - cold
4 + 5 - hot (same signal)
6 - hot
7 - cold
8 - hot
9 - cold
10 - hot
11 - cold
12 - cold
13 - cold
14 - hot
15 - cold
16 - hot
.

geolab

Yes, in fact if you sum up hot wiring in both layouts, round or OBD sync, porsche specific data comm is 10 connections, labeled from 0 to 9 in their tech sheets.
Yes, the same cable is used for the system tester for OBDI and OBDII, so logical, the same data lines as well as power, ground.
But does OBDI use all of the hot wire connections in the plug layout exactly the same as OBDII??? yes because on the round connector cable for the 964 still it is a 10 hot wire config, same same
honestly I don't know. but I fell on just one 993 with the round connector in the passenger footwell long time ago at the main dealer, and thought it was a US import.

IXLR8

I don't know what you mean by "hot" and "cold" in the above, but the interface I am building for my "OBD I Certified" system on my late '95 993 that uses an OBD II connector, uses pin:

3 for data
5 for signal ground, 0V
7 for data
15 for data
16 for power, +12V

It appears Porsche is using the ISO 9141 protocol.

geolab

this won't work

I gave you a hint above,
hot = wired
cold = no juice, no electric connection. nothing nada
no connection between interface and car (3 or 7 or all cold pins are dummy pins in a porsche cable) regards

IXLR8

Wired? Wired to what? My headlights?

I've never seen anything labeled as "hot" or "cold" unless we're sending someone on a search.

geolab

it's maybe what I retained from elec. engineering courses 25 yrs ago,
hot- current
cold - no current

what I mean is, in your example, pin number 3 or pin number 7 do not transmit anything between tester reader and car DME in a porsche pre 2004,
to insist, if I break the pins 3 and 7 on a porsche cable, the system tester works perfect.....regards Alex

IXLR8

Thanks, but that isn't any clearer.

The "bought" PC board and schematic that I have from a RLer shows the pins I mentioned as being used.

I will check my OBD II connector and actually check what is connected to which pin.

I'll figure it out. Thanks!

IXLR8

Geo, the above does not match my connector based on my observation. In fact, there is no connection at pins 2, 6, 8 and others.

I just measured and ohm'd out the actual pins on my connector with the ignition OFF and ON (not concerned about the latter at this point) and then removed my OBD II connector to take note of the wire colors which match those in the Porsche Repair Manual when I checked.

Voltages are DC with the ignition OFF (ON).
Pin 5 was determined to be GROUND (DMM beeped).

Pin 1: 0.000V – Orange (12.34V)
Pin 3: 1.997V – Orange/White (10.82V)
Pin 4: 0.000V – Brown (0.000V)
Pin 5: 0.000V – Brown (0.000V)
Pin 7: 0.040V – Orange/Black (6.87V)
Pin 9: 0.095V – Black/Violet (11.39V)
Pin 11: 0.006V – Yellow/Grey (0.044V)
Pin 13: 3.087V – White/Red (10.44V)
Pin 15: 2.838V – Orange/Blue (9.95V)
Pin 16: 14.59V – Red (12.88V)