I have a 95 Pontiac and I wanted to dump the error codes on it
to find out why the service light was on.
I went to the connector under the dash, and you're supposed to
be able to ground the 'Diag' pin at "B" to ground at "A" and it
kicks the computer into a diag dump mode.
But I don't have a connector pin at "B"
Yep, it's the 6x2 connector. Yep, the vin codes all match correctly
to let me know it's engine "M" for that year and it should have the
6x2 connector. But there's a TOTAL of 3 wires connected to the
A black wire at "A", which I'm assuming is ground
A tan (or light colored) wire at "M"
A green (I think) wire at "I"
In all the documentation I can find, there were NEVER any wires in
the 'lower row' in slots "H" to "L".
So... What gives? Any ideas? Ground should be fairly easy to trace
out, but what are the other two wires, and why are then in the slots
I found them at?
"80 Knight" <80 email@example.com - Remove SPMASUCKS To
If that car has the older "6X2" connector, then it is OBD1. HOWEVER,
most GM OBDI cars post 1993 do NOT have the capability of code reading
via the "Check Engine" light - you must use a scan tool to retrieve
codes (the "B" cavity in the ALDL connector is empty).
On top of that, the 94~95 cars are kinda a hybrid - OBDI
electrically (ALDL connector, etc.) but semi-OBDII as far as the data
stream (codes similar to, but not exactly the same as, OBDII codes).
My '94 Regal with a 3800 Series I is like that.
There are some '95s that ARE OBDII - the 3800 Series II and the 3.4
engines are 2 examples. The '95 3800 Series I engine is a hybrid OBDI
as is the 3100, which is the engine you have..
The added used pins in the connector are for connection to the ABS
computer and the E&C data line (radio, HVAC, etc.).
Thanks for the details. After I posted, I found one online reference that
there were some 95s that would not dump the codes, but no explanation
as to why. What was throwing me was the fact that it used the 6x2
connector. Then the fact that it only had 3 wires to it, and other than
ground and data, the 3rd wire to 'J' (I didn't realize that they skipped
isn't documented ANYWHERE.
I'd love to make up my own interface to see what I can do. But about
the only thing I can find out is that the baud rate is a 'custom' at 8192.
I haven't been able to find specs or protocols.
Mike, I feel sure 80Knight is correct. 95's had OBDII yet inside an
OBDI connector, Scanners use a special connector wire for just this one
year--at least that is the way it is on 95 Z28, Corvettes, etc with the LT1
engines. I feel like other95's were affected the same. s
From what I've been able to dig up, 95's are a bastard year. They are
'beyond' OBDI in what they can do, sort of a pre-OBDII. They also do
not have any manual dump mode. But they are not OBDII compliant.
Almost as if they were an interim subset of OBDII used for development
with the intent of finally ending up as OBDII compliant. That may explain
why they work with OBDII tools if you have the wire converter. I'll
lay odds that the OBDII spec either includes a 'version number' that
determines the level of support, or does something similar to a 'valid
function list' that is communicated between the tool and the vehicle when
Bill seemed to hit it pretty close to what I've been able to find out.
Now if I can just get some kind of spec... It's gotta be out there on the
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