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Username Post: OBD2 port        (Topic#369025)
bmnloader 
Newbie
Posts: 14

Reg: 06-23-17
07-24-22 08:26 AM - Post#2844843    

I have a 65 C10 that has been LS swapped. I bought it this way, I didn't build this one. I cannot find a OBD port anywhere. I know where the computer is but... The guy that did the wiring is not around anymore. Where would you put it?



 


Shepherd 
Valued Contributor
Posts: 2626

Loc: Lake George, NY
Reg: 11-11-15
07-24-22 10:23 AM - Post#2844848    
    In response to bmnloader

You'd think under the dash, easily accessible, or under the hood, likewise.



 
jktucker92 
Silver Supporting Member
Posts: 535
jktucker92
Loc: West Richland, WA
Reg: 02-05-17
07-25-22 07:36 AM - Post#2844882    
    In response to Shepherd

The OBD2 ports are designed for in the cab, so it should be there. Typically just under the dash, to the left or right of the steering column. It's possible that it wasn't ever installed. I'd trace the wiring harness. There should be a place where the harness goes through the firewall from the PCM. If not, you're missing several wires that are important. To get all the features of the LS conversion, there's the OBD2 port, brake switch inputs to the PCM, and check engine light that all need to be brought into the cab.
Did somebody modify a stock harness? If so, do you know what the donor vehicle is? If there's no OBD2 port now, you'll want to find a way to add it. If you know the donor vehicle, there's likely a connector that's part of the donor vehicle harness that just needs the mating connector wired into the cab for the OBD2 port, brake light inputs, and check engine light. It's likely these wires are bundled in a connector with the wires used for the start and run signals from the ignition switch.



 
bmnloader 
Newbie
Posts: 14

Reg: 06-23-17
07-26-22 08:37 AM - Post#2844939    
    In response to jktucker92

That's what i thought. I've traced wires and there isn't a port i can find. No idea what the donor was.



 
Shepherd 
Valued Contributor
Posts: 2626

Loc: Lake George, NY
Reg: 11-11-15
07-26-22 01:57 PM - Post#2844957    
    In response to bmnloader

Ask the previous owner?



 
jktucker92 
Silver Supporting Member
Posts: 535
jktucker92
Loc: West Richland, WA
Reg: 02-05-17
07-26-22 02:17 PM - Post#2844958    
    In response to Shepherd

If you can take some photos of the engine, harness and computer I'll try to help out. I've done a few LS retrofits and modified stock harnesses, and have browsed lots of information about it. Are there any connectors that are unused around where the harness connects to the PCM? If so, take pictures of those and I'll see if I can help out.



 
Tony1963 
Frequent Contributor
Posts: 1552

Loc: Orlando Florida
Reg: 07-09-18
07-27-22 06:44 PM - Post#2845031    
    In response to bmnloader

I cannot imagine doing the LS swap and using the factory wiring harness, then somehow cutting out the OBD II connector.

I would venture to say that it is somewhere under the dash probably zip tied out of the way.

People fear change because it threatens what they know, or what they claim to know.


 
jktucker92 
Silver Supporting Member
Posts: 535
jktucker92
Loc: West Richland, WA
Reg: 02-05-17
07-27-22 08:33 PM - Post#2845037    
    In response to Tony1963

For the 2004 truck harness I used, the OBD2 wires went through a connector, then through the firewall, before being terminated at the OBD2 port. If you only grabbed the engine harness, you would not have received the OBD2 port. There's no cutting to remove the OBD2 port, you just don't add the wire harness that has the OBD2 port on it. I can't speak for the other factory harnesses, but that's the way the 2004 truck harness is.



 
bmnloader 
Newbie
Posts: 14

Reg: 06-23-17
07-28-22 08:37 AM - Post#2845049    
    In response to jktucker92

The harness is from a 2001 Silverado. Cant get pictures at the moment but I will. PCM is in the passenger side kick panel.I don't think it's from the donor truck. Looks aftermarket to me



 
jktucker92 
Silver Supporting Member
Posts: 535
jktucker92
Loc: West Richland, WA
Reg: 02-05-17
07-29-22 07:40 AM - Post#2845106    
    In response to bmnloader

Interesting. Definitely not a stock '01 harness if the PCM is behind the kick panel. The stock location of the PCM would be the driver side near the front of the fender. Moving it to the passenger side kick panel would require a lot extension. An aftermarket harness definitely should have an OBD2 connector somewhere. The data wire from the PCM is on the Blue connector, pin 58, should be a dark green wire. Not sure how hard this will be to trace, but that's the wire that needs to go to pin 2 of the OBD2 connector. Pin 4 of the OBD2 connector is a ground, and pin 16 is just battery +. Pin 5 is the PCM ground, which should be a black wire with a white strip coming from the PCM.



 


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