I have a 2002 5.3 engine that came with a harness that had both computer connectors and a few other various connectors cut off. I got another used harness that had a few connectors missing, but the rest is in great condition so between the two I'm making one complete good harness. I'm done thinning it out and making all the repairs necessary except for 2 things.

1. The harness that came with the engine had only one O2 sensor connector and it is a white square 4 wire plug whereas the replacement harness has O2 sensors connectors that are black and flat with 4 wires. Are these okay to use, but with different O2 sensors. Why would they be different?

2. Transmission connections. I think I'm looking at harnesses that were equipped for 2 different transmissions. I want to go with a 4L60E trans. What wiring and connectors do I need to have it work? On the transmission branch for the harness that came with the engine there are 4 connectors. One I believe is an O2 sensor (white square). Obviously the main round connector for the transmission. One is the VSS. What is the fourth connector? There are only 3 wires going into it. Please see attached picture for what I'm talking about.

On the transmission branch for my replacement harness I have an O2 connector (flat), round main transmission connector, VSS and 6 wires with the plug missing that I traced to the main computer connectors that I have confirmed to be for the transmission range selector. These 6 wires are not in the harness that came with the engine. Can you tell me where I can purchase this connector and if in fact this is the correct setup for a 4L60E?

The 6 wires are...
Blue connector - Pin 72 (Range Selector)
Blue connector - Pin 32 (PRND A Input)
Blue connector - Pin 40 (PCM Ground)
Blue connector - Pin 34 (PRND P Input)
Red connector - Pin 62 (PRNDC Input)
One pink wire - 12V Ignition +

Thank you,
Kevin C

 

I believe the 3 wire connector is for 4wd application. Im trying to find diagrams/pics to verify . I have a harness out of an o1 1500 that doesn't have it . And both of my harnesses had 4 o2's. 2 front and 2 for the rear. one harness had 4 square o2 connectors and the other had 2 flat and 2 square. I went with the 2 flat for the front o2's due to the part store pulling o2's with that connector when i asked for the replacements.

 

Check LT1swap.com for the O2S plugs. If I recall correctly, the square plugs are for pre-cat O2s, flat plugs are for post-cat O2s. Black and white plugs are for the two types of O2S grounds used in 02-03. Some are separated, and some share one big ground splice in the harness somewhere. What you use depends on the PCM you have.

Found it:

http://lt1swap.com/vortec_o2_sensors.htm

 

Thanks for the information. From what I understand the style of plug in is directly related to if the O2 sensor is case or isolated grounded. Looks like I need to buy a pair of flat plug O2 sensors and one pigtail.

Any ideas on my transmission range situation? Where can I get that connector from? Is the wiring I currently have compatable with a 4L60E?

Thank you,
Kevin C