Single Purple Wire in engine bay 1989 K1500

[johnsonmtz]

I'm tracking down a no spark condition on my 1989 K1500 5.7L . While probing around the distributor I came across this single wire plug with a purple wire coming out of the main harness. For the life of me I can't find where this plugs into. I don't know that it has anything to do with my no spark condition, but I'd really like to know the purpose of this wire & connector and make sure it's correct. I recently had my transmission rebuilt at a local shop and I'm wondering if this somehow got unplugged in the removal or reinstall process, but I just can't find where it goes.

Please help me track this down.

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[Caman96]

Download the free service manuals on the forum. To me that looks like a BLK/Pink wire.

 

[scott2093]

That's not an o2 sensor connector is it?

 

[johnsonmtz]

That's not an o2 sensor connector is it?

It sure could be the O2. There is a single wire connector on the driver side coming out of the harness that connects with the O2 sensor wire. Is there another connection elsewhere? I was certain these only had a single O2 sensor on the driver side manifold, but is there a provision for a 2nd sensor on the passenger side?

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[Scooterwrench]

That's for a second O2 sensor. 4.3's ran two sensores and GM made up the wiring harness to service all V configured engines of that era. My 91 has it too.

 

[johnsonmtz]

Download the free service manuals on the forum. To me that looks like a BLK/Pink wire.

I can't see any stripes on the wire, it looks solid purple to me unless they used a really dark color for pink. I have the manuals but I'm having a hard time tracking down a PNK/BLK color wire.

 

[johnsonmtz]

That's for a second O2 sensor. 4.3's ran two sensores and GM made up the wiring harness to service all V configured engines of that era. My 91 has it too.

Gotcha, now I don't feel quite as crazy. Is there any advantage to running a 2nd O2 sensor? I didn't think the PCM on these older ODB1 would do anything with data from more than one sensor.

 

[Caman96]

I can't see any stripes on the wire, it looks solid purple to me unless they used a really dark color for pink. I have the manuals but I'm having a hard time tracking down a PNK/BLK color wire.

Ok, the other one is blk/pink I’m seeing. I’d look at mine but it’s a Vortec.

 

[Scooterwrench]

Gotcha, now I don't feel quite as crazy. Is there any advantage to running a 2nd O2 sensor? I didn't think the PCM on these older ODB1 would do anything with data from more than one sensor.

I don't think so. The two wires are connected together in the harness.
K.I.S.S.!!!!

 

[johnsonmtz]

I don't think so. The two wires are connected together in the harness.
K.I.S.S.!!!!

That's what I figured. Re-reading your post on the 4.3L using two but GM using a universal harness makes a lot of sense. KISS indeed.