Can't scan my damn pcm.

[LM13]

Can't get the pcm codes out.
I tryed scanning the pcm and everytime i get to the part where you have to connect it to the pcm it just doesn't see the connection.
shouldn't there be a positive wire in the connector? coz i poked around and there isnt.
i'm thinking maybe the positive wire got cut or something.
btw i have a 96 9c1 with OBD not OBDII.
i shorted the two wires together instead of souldering something into the pcm, could it be that aybe that short broke?
thanks alot

[Incitatus]

It seems to me that the Haynes has a wiring diagram in it. See if you can find where that hot wire is supposed to be. Also, that hot wire may want its own dedicated ground -I don't know, maybe.

If your car seems to be running ok, it's probably just the diagnostic wiring at fault.

Let me know if you can't find the diagram and I'll see if I can't scan mine and post it.

[LM13]

Originally posted by Incitatus
It seems to me that the Haynes has a wiring diagram in it. See if you can find where that hot wire is supposed to be. Also, that hot wire may want its own dedicated ground -I don't know, maybe.

If your car seems to be running ok, it's probably just the diagnostic wiring at fault.

Let me know if you can't find the diagram and I'll see if I can't scan mine and post it.

thanks
i'll ask dr to look at his manual.
hopefully it will have that.

[Incitatus]

How much of the OBD I system do you have? The wiring harness and pcm or just the pcm?

I looked at the wiring diagram for the OBD I and it appears that the ground wire for the diagnostic connection is a black wire with a white stripe and next to it is a white wire with a black stripe. I'm going to assume that is your power (not necessarily 12vdc) because the other wires going to that connection aren't.

I'm sorry I don't have pin numbers for them.
I know the black with white stripe is definitely ground (it's at the diagnostic connector) and I know there is a pink wire that is key-on hot and there is a purple (with a stripe) that is constantly hot (they both go to the pcm).

All that may or may not be of any help.

[LM13]

none of them are hot even with the key on!!

[Incitatus]

Where are you getting your ground? chassis? from the battery negative? Like I was saying earlier, it may want its own ground.

Also, the thought occurred to me, it may operate off of phantom power. Sometimes 48 volts are sent through signal wires with a very, very small amount of amperage (nearly undetectable).

Does the reader have its own batteries? There's a very good likelihood that there is no voltage at the terminal and the reader is getting its power somewhere else.

Can you check someone else's car that has a similar setup as yours?

[LM13]

Originally posted by Incitatus
Where are you getting your ground? chassis? from the battery negative? Like I was saying earlier, it may want its own ground.

Also, the thought occurred to me, it may operate off of phantom power. Sometimes 48 volts are sent through signal wires with a very, very small amount of amperage (nearly undetectable).

Does the reader have its own batteries? There's a very good likelihood that there is no voltage at the terminal and the reader is getting its power somewhere else.

Can you check someone else's car that has a similar setup as yours?

i'm sure it is not the reader, coz i've tryed to different ones.
i thought about the ground. but i haven't really dug into it yet.

[Incitatus]

No, not the reader. I wan't really expecting it to be at fault.
I was suggesting that you try to find the hot wire on someone else's car.

[LM13]

Originally posted by Incitatus
No, not the reader. I wan't really expecting it to be at fault.
I was suggesting that you try to find the hot wire on someone else's car.

oh
thats what i was thinking of doing.
not too many 96s around here tho :)