OBD2 Port Help?

[bbluma]

Hey yall, hope I don't sound too much like an idiot here but got a question or two about OBD2 ports. So Im working on my 66' c10, and PO had swapped it with a driveline out of a 1999 Tahoe. So engine was starting to run bad right before we started the upgrade of new fuel lines and a EFI setup pump/tank. Seemed like it was starving for fuel maybe, started popping really bad, and kinda just running in and out.

My question is this, we haven't been able to find the OBD2 port anywhere, and I assume the PO just cut it out. Where does it run back into? And is it possible to run another one? Reading the codes would make diagnosing the engine a whole lot easier. If it is a dumb question you can say it haha, im just curious if its possible.
Thanks.

[B. W.]

If it has the stock ECM / PCM you can wire in an OBD 2 port. There is a web site (can't remember name) that has the pinouts for the stock computer & for the GM "411" (for switching to the "411" computer, you have more tuning options) Here's what I have:

Data Link Connector pinouts:
Pin 1 - not used
Pin 2 - purple, serial data signal, class B (pin 11, connector 4 on PCM)
Pin 3 - not used
Pin 4 - black, ground
Pin 5 - black/white, VCM ground (pin 17 & pin 18, Connector 3)
Pin 6 - not used
Pin 7 - not used
Pin 8 - black/white, keyless entry (don't know, believe it goes to BCM - Body Control Module) if no keless entry, ignore
Pin 9 - Tan, SIR serial data (same as above)
Pin 10 - not used
Pin 11 - not used
Pin 12 - not used
Pin 13 - Orange, diagnostic signal for TCM (goes to Transfer Case Module, don't know pinout, if 2wd ignore)
Pin 14 - Dark Green, diagnostic, entertainment & comfort (ignore)
Pin 15 - not used
Pin 16 - orange, fused battery

[bbluma]

Okay, so googling around I found that as well as another with not as many wires, what's the difference?

http://m.ebay.com/itm/OBDII-OBD2-Wir...b%257Ciid%253A

http://m.ebay.com/itm/16-Pin-J1962-O...%257Ciid%253A4

thanks.

Originally Posted by B. W.

If it has the stock ECM / PCM you can wire in an OBD 2 port. There is a web site (can't remember name) that has the pinouts for the stock computer & for the GM "411" (for switching to the "411" computer, you have more tuning options) Here's what I have:

Data Link Connector pinouts:
Pin 1 - not used
Pin 2 - purple, serial data signal, class B
Pin 3 - not used
Pin 4 - black, ground
Pin 5 - black/white, VCM ground
Pin 6 - not used
Pin 7 - not used
Pin 8 - black/white, keyless entry
Pin 9 - Tan, SIR serial data
Pin 10 - not used
Pin 11 - not used
Pin 12 - not used
Pin 13 - Orange, diagnostic signal for TCM (Transfer Case Module)
Pin 14 - Dark Green, diagnostic, entertainment & comfort
Pin 15 - not used
Pin 16 - orange, fused battery

[B. W.]

all of the OBD connectors are 16 pin, you only need the 4 wires listed above, I believe you can ignore the rest.

Pins 2,4,5 & 16

I didn't give you the pinout for pin 5,
Pin 5 goes to pins 17 & 18, connector 3 on PCM

[bbluma]

ahh okay gotcha. Just curious, why do they make them 16 pin if you only end up using 4?

[Captainfab]

You first need to know which PCM you have.
Do you know if it has been reflashed? If so, what was done and functions deleted or modified in the reflash?

If you do have the 411 PCM that is a bonus providing the conversion was done correctly.

Here is the forum with loads of info on the '96-'02 Vortec 350's

http://www.pacificp.com/forum/index.php

[bbluma]

hey Captain, seems you just know about everything don't ya? haha

Whats the best way to figure out what PCM I have? Im not 100% sure if its original or not, PO did some rough wiring....

a quick google says that the ECM looks to be like a stock Tahoe one (vehicle motor came out of), so that may be good? Whats the difference between PCM and ECM? tad bit confused at this point.
Thanks.

[bbluma]

Here's a pic of the Ecm that truck is using from PO.

[B. W.]

That's the stock PCM. Nothing wrong with it. It was only used for a short time & the aftermarket companies don't have much support for it. On a stock engine it is fine.

the OBD connector has 16 pins to allow for additional info / options. Some wires are standardized across all makes / all models ( like power & ground) some are used for various functions at the discretion of the builder.

[Captainfab]

PCM=Powertrain Control Module
ECM= Engine Control Module

What you have is a PCM since it also controls the transmission. That is just the original black box PCM that came in the Tahoe. The other side of the PCM will have a tag with the service number of the PCM.

So you have no idea if and or what the PO had done to the PCM? If so, that could be your problem if it has not been reflashed to run as a standalone or at least without some components functioning.Does the installation have 2 or 4 O2 sensors?

[bbluma]

I have no idea, the PO of the PO is who swapped the engine and all so I'm lost there. And I believe there is 2 O2 sensors. What's it take to reflash it if that's the case?
Thanks.

Originally Posted by Captainfab

PCM=Powertrain Control Module
ECM= Engine Control Module

What you have is a PCM since it also controls the transmission. That is just the original black box PCM that came in the Tahoe. The other side of the PCM will have a tag with the service number of the PCM.

So you have no idea if and or what the PO had done to the PCM? If so, that could be your problem if it has not been reflashed to run as a standalone or at least without some components functioning.Does the installation have 2 or 4 O2 sensors?