O2 sensor help (94 k3500)

[Road Trip]

I think I found a match in the '94 Electrical FSM for the Lt Green / Blue combo. Q: Are your backup lights operational?
Is there anything connected to that switch in your manual trans?

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I looked up C366 in the Connector section of the '94 Electrical manual in order to give you a connector shape to look for:

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Hope this helps --

 

[jd33173]

Gmt400 detectives are on the case! Fun to watch

 

[chris032188]

I looked up C366 in the Connector section of the '94 Electrical manual in order to give you a connector shape to look for:

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Hope this helps --

It's dark here now, I'll poke around more. Just did trans fluid and glad I did because only about quart and half came out.

Gmt400 detectives are on the case! Fun to watch

I know, it's crazy how knowledgeable they are. I just moved into my house not to long ago and haven't set up my computer (because I'll know I'll waste time dicking around on it) but it makes it a PITA trying to find **** in the manuals on my phone. These guys are wizards.

 

[someotherguy]

Middle pic is definitely the connector that goes to a pressure switch in the back of your AC. Just installed a Sanden upgrade on my 99 burb cause the OEM compressor seized and took out the tensioner pulley along with it.

That red connector almost certainly goes to the AC condenser

Those pics with the three connectors that have the wires zip-tied together..

Yes, the middle pic - round connector goes to the pressure switch on the back of the A/C compressor.

Top pic - flat 2-pin goes to the clutch connector behind the A/C compressor pulley.

Bottom pic - red 2-pin connector is going to be the canister purge solenoid (1994-1995 TBI only)

Richard

 

[dmhscorpion]

Got o2 sensor in looks like the Barrell connector was on a purple wire. It's reading on scanner so I think it's right. A portion of my harness that's in that loom was ripped (I think it got caught on drive shaft. I'm repairing that now. Just patched speedo sensor but I see some more wires and a bare wire (this was in same tight wrapped peice speedo was in). It looks a light green and blue together, and a black with white stripe by itself. Anyone know what these are for? I don't see anything under here they could run to

My harness to the transfer case on my 99 2 door Tahoe was wrapped around the driveshaft due to the "mechanic" not securing it after changing the transmission at 285K, I used this type of connector. They are still holding up after 7 years ...

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YMMV ...

 

[Oakr11]

If you check the factory service manuals (available here free to download, check the sticky'd posts at the top of this section) - there are wiring diagrams for each possible drivetrain combination in each year.

While heated (3 wire) O2 sensors were first seen on these trucks in 1994, and I've had them with the 3 wire.. I am fairly sure your manual transmission model had the non-heated (1 wire) O2. You should confirm with the factory service manual, though.

Richard

I have a ‘91, ‘92, and a ‘94 and they all have one 1 wire O/2 sensor. I have the GM service manual for all three and they show one wires. It is a good to help the ecm do its job better if you add a heated O/2 sensor!

Found the O2 connector dangling under truck next to some ripped wires I had. I have these 3 open connectors up top - anyone recognize them?

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the black one is most likely the A/C low pressure switch connector!

 

[GoToGuy]

The purpose of a heated 02 sensor was to further reduce emissions by preheating the sensor so it " comes alive " quickly. Rather than extended time period before it gets to operating temperature and provides feedback.

 

[udidwht]

94 year was a bit of mixed bag of nuts. Some came 3 and some came 1 wired. The O2 on my P-30 series (1994) was 1 wired.

 

[GoToGuy]

It's confusing. The 350 can be different than the 305. Then the 350 is different again if it's over 8500 lbs. Then changes again if its sold in a state that follows Calif Carb emissions.
Both Calif trucks , both 350, 91 one wire. 95 3 wire.

 

[pandatruck]

94 auto here with a one wire o2