OBD1 Code Retrieval

[RolandMD]

I have a 95 APV with a solid SES light. To get the codes, according to the Haynes Manual, on the "Assembly Line Data Link" (diagnostic connector) I need to use a jumper wire (or paper clip) and ground out pin A (ground) and pin B (diagnostic terminal) on the diagnostic connector. The connector has pins that look as follows:

F E D C B A
G H _ _ _ M

A is the ground, and B should be the diagnostic terminal, but there is no wire going to B. What I have is a black wire with a tracer going to A, a tan wire going to M, and a purple wire going 2 holes to the left of M (the manual has no letters for these 3 pins). Near as I can tell, the tan wire (M) is the serial data pin. So which two do I ground out to get the trouble codes?
Thanks!!!!
Roland

[danielsatur]

The OBD I scanner is cheaper, but consider the one thats does both OBD I, and OBD II systems.

A local Auto parts can pull code for free, it's too hard to read morse code!

[RolandMD]

Originally Posted by danielsatur

The OBD I scanner is cheaper, but consider the one thats does both OBD I, and OBD II systems.

A local Auto parts can pull code for free, it's too hard to read morse code!

Appreciate it! Problem is that pre-OBD II (OBD I) there were many different diagnostic connectors. Each manufacturer seemed to have his own. It wasn't until OBD II that the connectors were uniform. The auto parts guy told me that they don't have all of the scanners for pre OBD II and couldn't read my codes for me.
I have the codes in my Haynes Manual, but I can't get the codes until I know which pin to ground with the ground (A). Then I can count the flashes and find the codes.
Once again, thanks!! Appreciate all of the help I can get.

[danielsatur]

If getting no codes -
1) Check fuse for the ECU.
2) Disconnect the ECU, clean connections, and reseat connector.

Tools: Brass like tooth brush, and CRC electrical cleaner.

[RolandMD]

Originally Posted by danielsatur

If getting no codes -
1) Check fuse for the ECU.
2) Disconnect the ECU, clean connections, and reseat connector.

Tools: Brass like tooth brush, and CRC electrical cleaner.

Once again, thank you. Perhaps I should restate my problem. In order to get the codes, one must ground out "A" on the connector (which is the ground) to "B" on the connector (which is the diagnostic). Once these two are grounded, turn the ignition on (do not start the engine) and count the flashes of the SES light on the dash. Unfortunately, in my APV, there is no wire coming to the back of "B" in the connector.
I have only 3 wires coming into the back of my connector. There is the black wire with a tracer in "A" (top right on the connector), and this is the ground. There is a tan wire in "M" (bottom - just below A). The only other wire that I have is a purple wire that is 2 spaces to the left of "M" on the bottom row (no letter given in the manual).
Question, do I ground out "A" with "M" to get the codes, or do I ground out "A" with the purple wire? Or, (and I guess this is a possibility), am I for some reason missing the appropriate wire(s)? I read that if I do it wrong, I can damage the PCM. Ugh!!!!

[Jeffrv]

Beginning in 1994, GM began the migration to the ultimate goal of all vehicles being OBD-II compliant, and these vans were in the 20% or so that were sent over prior to 1996. Actually, it is a hydrid, mostly OBD_II compliant, yet packed in an OBD-I form. You have oberserved this by the changes in the ALDL connector.
The short story to this is that you cannot use the paper clip trick on 94 and 95 vans, a scan tool has to be used, just as you do for 96 and up OBD-II. If you buy a scan tool, make sure it will in fact read that van, a lot of the more inexpensive ones may only read true OBD-I, and not the vehicles that were caught half way between the 2 systems
Jeff

[RolandMD]

Originally Posted by Jeffrv

Beginning in 1994, GM began the migration to the ultimate goal of all vehicles being OBD-II compliant, and these vans were in the 20% or so that were sent over prior to 1996. Actually, it is a hydrid, mostly OBD_II compliant, yet packed in an OBD-I form. You have oberserved this by the changes in the ALDL connector.
The short story to this is that you cannot use the paper clip trick on 94 and 95 vans, a scan tool has to be used, just as you do for 96 and up OBD-II. If you buy a scan tool, make sure it will in fact read that van, a lot of the more inexpensive ones may only read true OBD-I, and not the vehicles that were caught half way between the 2 systems
Jeff

Ahhhh! Makes sense, and fits my luck! LOL Thanks for all of the help guys.
Merry Christmas (if you keep it).
Roland

[MT-2500]

Originally Posted by RolandMD

Ahhhh! Makes sense, and fits my luck! LOL Thanks for all of the help guys.
Merry Christmas (if you keep it).
Roland

http://www.troublecodes.net/GM/

[RolandMD]

Originally Posted by MT-2500

http://www.troublecodes.net/GM/

Thank you! I went to the website and hopefully the image of the diagnostic connector will help to explain a little better.
I am instructed to ground terminal (or pin) "B" with pin "A" (can use a paper clip) and then turn the ignition on - then count the flashes of the SES light.
My problem is that there is no wire going to "B" at all! All I have in my diagnostic connector are: "A" (a black wire with a tracer), "M" (a tan wire) and 2 spaces to the left of "M" there is a purple wire (no letter given). Thus my dilemma! There are only 3 wires going into my diagnostic connector (yes, it is a 95 Lumina APV).
Thanks again,
Roland

[MT-2500]

Originally Posted by RolandMD

Thank you! I went to the website and hopefully the image of the diagnostic connector will help to explain a little better.
I am instructed to ground terminal (or pin) "B" with pin "A" (can use a paper clip) and then turn the ignition on - then count the flashes of the SES light.
My problem is that there is no wire going to "B" at all! All I have in my diagnostic connector are: "A" (a black wire with a tracer), "M" (a tan wire) and 2 spaces to the left of "M" there is a purple wire (no letter given). Thus my dilemma! There are only 3 wires going into my diagnostic connector (yes, it is a 95 Lumina APV).
Thanks again,
Roland

As the link tells you.
And Jeffrv told you.
Quote from the bat link.
NOTE: Some 94 & 95 models do not have the B terminal. In which case a scanner is required.
NOTE: Some 94 & 95 models that DO have the A & B terminals still require a scanner.
All vehicles after 96 are OBDII,and require a scanner to access them.

Also a special scanner and adapter is required for the 94-95.
Very few auto parts places can read the 94-94 codes if no B pin/wire and even some with the A and B pin.

You will need the special scanner and adapter and engine cartriage for that year.