DIY standalone wiring help
Thread Starter
Staging Lane
Joined: Jul 2019
Posts: 62
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DIY standalone wiring help Hello folks. I'm diving head first into my first LS swap and I've got some wiring questions I was hoping someone could help me with. So far I have pulled all of the un-needed wires from the PCM plugs, but I haven't started mapping out my external connections yet. I've removed the A/C compressor plugs and I'm running a manual trans, so I've removed everything transmission related except for Blue pin #34 in case a crank relearn is needed. For reference, this is a DBC 2002 L59.
Here's the problem, my harness was cut in 2 places. From what I can tell, all that was cut off were the O2 sensors (which I have with pigtails, there's just a length of wire missing) and the transmission, range sensor, and speed sensor plugs. From what I can tell, the O2 sensors are the only things that I need out of all of that, so I can just solder them back in. What I'm a little fuzzy on is the mass of Tan wires that are in the branch that went to the transmission plugs. There's a large splice where they all come together and the cut is immediately at the other end of that splice. I'm assuming those are some sort of COM wire, but I'm really not sure what to do with it. Is there any connection on the other end of it that I will need to compensate for (like do they go to the O2 sensors) or can I just leave the splice where it is and ignore it?
Here's the problem, my harness was cut in 2 places. From what I can tell, all that was cut off were the O2 sensors (which I have with pigtails, there's just a length of wire missing) and the transmission, range sensor, and speed sensor plugs. From what I can tell, the O2 sensors are the only things that I need out of all of that, so I can just solder them back in. What I'm a little fuzzy on is the mass of Tan wires that are in the branch that went to the transmission plugs. There's a large splice where they all come together and the cut is immediately at the other end of that splice. I'm assuming those are some sort of COM wire, but I'm really not sure what to do with it. Is there any connection on the other end of it that I will need to compensate for (like do they go to the O2 sensors) or can I just leave the splice where it is and ignore it?
Thread Starter
Staging Lane
Joined: Jul 2019
Posts: 62
Likes: 3
25 TAN1671HO2S Signal Low B2S2 (w/Case Ground O2 Sensors)
25 TAN413HO2S Signal Low B2S2 (w/Isolated Ground O2 Sensors)
26 TAN1667HO2S Signal Low B2S1 (w/Case Ground O2 Sensors)
26 TAN413HO2S Signal Low B2S1 (w/Isolated Ground O2 Sensors)
27----Not Used
28 TAN/WHT1669HO2S Signal Low B1S2 (w/Case Ground O2 Sensors)
28 TAN413HO2S Signal Low B1S2 (w/Isolated Ground O2 Sensors)
29 TAN/WHT1653HO2S Signal Low B1S1 (w/Case Ground O2 Sensors)
29 TAN413HO2S Signal Low B1S1 (w/Isolated Ground O2 Sensors)
Thread Starter
Staging Lane
Joined: Jul 2019
Posts: 62
Likes: 3
I may have found the solution to my own question. From the pictures on lt1swap, I have "isolated ground" style O2 sensors. This is what they have to say about that:
So I do need to wire my O2 sensors to the brown splice (I'm only using the front 2). What I wouldn't give for that to not have been cut off so close to the splice.
ISOLATED GROUND sensors: This type of sensor, gets its ground FROM the PCM. The body of the sensor IS NOT connected to the TAN wire going to the PCM. So the TAN wires need grounded from another point. All TAN wires going into a splice pack, located inside the wiring harness. This splice is located on the part of the harness, that goes down the back of the intake, going toward the transmission connector. It is about 6-8 inches down from the top of the intake. Tan wires from each of the 4 sensors enter the splice, and 5 TAN wires go to the PCM. 4 of the TAN wires go to the SAME location as the case ground schematic above, but a 5th wire to the PCM goes to BLUE PCM connector pin 63. Pin 63 is a Low Reference (or ground) This simply gives a better ground path for the oxygen sensors. The sensor has a SQUARE 4 pin WHITE connector for the before cat o2 sensors. I THINK the after cat 02 sensors had a SQUARE 4 pin WHITE connector as well.
