Heated o2 conversion wiring

[tayto]

Gray wire is fuel pump. It will work with a relay but it will turn the 02 heater on for 2sec then off then back on when it gets a tach signal.

I am not seeing the problem here. it has worked fine on dozens of TBI vehicles i have converted to 3-wire O2s over the last 17 or so years. it also doesn't need an additional relay.

 

[Scooterwrench]

Didn't say it was a problem.

 

[DerekTheGreat]

GM powered the HO2S off the same wire that powered the egr solenoid. It doesn't draw much power(400 milliamps iirc).

...but in the 90 manual, The Pink/Black wire (circuit 920) looks to be the wire that powers the pump only when the engine is cranking or running. If that's correct, that's where I'll attach my o2 relay trigger wire. So, the heater should only operate when in Start or Run position if the engine is running, but NOT in Run position of the engine is zero RPM. I'm not super good at old skool schematics, so I hope I got that right....

I'm looking to do this swap. Checked my O2 cross counts the other day and they were 4 or less. Which of the two wires would be easiest to tap into and hide? Also, what is the preferred way to tap into a wire? Salt spray is a major issue where I'm at, so I'd like to make sure whatever I do stays corrosion free.

 

[someotherguy]

I'm looking to do this swap. Checked my O2 cross counts the other day and they were 4 or less. Which of the two wires would be easiest to tap into and hide? Also, what is the preferred way to tap into a wire? Salt spray is a major issue where I'm at, so I'd like to make sure whatever I do stays corrosion free.

Check the 1994 factory manual wiring diagrams. C1500 or C2500LD w/5.7/4L60E had heated O2 from factory, as did most of the other models, but that one's a for-sure.

Richard

 

[Road Trip]

Check the 1994 factory manual wiring diagrams. C1500 or C2500LD w/5.7/4L60E had heated O2 from factory, as did most of the other models, but that one's a for-sure.

Richard

@DerekTheGreat ,

Optimizing/modernizing the primary closed loop sensor would be something that appeals
to me, so I decided to look up what someotherguy was referencing. In the
'94 Driveabiilty, Emissions, Electrical Diagnosis & Wiring manual I found the
following wiring diagram showing both Single Wire & 3-wire Heated O2 sensors,
making for a nice comparison:

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Note: The factory power connection for the O2 heating element is connected to the '4WD' fuse.
(Side-note: Possibly this is the non-4WD-related thing that this fuse affected on a 2WD truck
that @Schurkey was referencing in a recent thread?)

Here's confirmation of the above with some additional detail on what all is connected to the
4WD fuse. Of interest is the "LB4 only" notation for the heated O2 sensor? Of course, a lot
of things can happen between when the manual was written and when trucks are popping off
of the end of the assembly line later on.

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As for splicing into this circuit, I'm from the Western Union splice, soldered & heat shrinked
school of thought. Solid mechanical, high conductivity connection first, preserved permanently
with the solder, and further weatherproofed/insulated with the heat shrink. I've never had
to revisit any connection made this way.

Of course there are many other reliable, permanent connection methods out there, possibly
someone can jump in with something easier, yet will still outlast the rest of the wiring harness?

****

Anyway, hope this clarifies how GM documented the added heated O2 sensors back in '94.

Cheers --

 

[Schurkey]

My preferred method of splicing wires is to crimp, then solder, then heat-shrink with tubing that has adhesive on the inside--essentially hot-melt glue.

"S" terminal starter solenoid wire on my '97 K2500 that had rotted at the starter end. I can't find "purple" wire in 12-gauge, so I used red instead. There's about three feet of new wire, from topside of engine, down behind bellhousing, and then forward to the solenoid. The original wire had been crudely repaired by previous owner, and had rotted again so far behind the bellhousing that I had no access to fix it there.

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I'm not saying I do this on every splice I make. I have been known to short-cut this to "Western Union" and solder and heat-shrink, or crimp (no solder) and heat-shrink.

Scooterwrench posted a sticky thread in the Engine section about this.
www.gmt400.com/threads/lets-get-connected.63797/

Let's get connected!!!

No,I'm not trying to create a new online dating site,like we need any more of those. This thread is about wiring and the correct way to make connections. I look at some of y'alls wiring under your hoods and think "Holy sheepsh*t Batman,how can that thing even run" I know y'all are doing the best...

www.gmt400.com

 

[Schurkey]

(Side-note: Possibly this is the non-4WD-related thing that this fuse affected on a 2WD truck
that @Schurkey was referencing in a recent thread?)

I swear I thought I read a thread about a 2WD truck needing a fuse in the "4WD" slot of the fusebox. Stabbing a fuse back into that position fixed "something" maybe even multiple "somethings".

The only thread like that, that showed up when I did a search, involved NOT having a fuse there.

I like the idea of me not being senile, and not hallucinating.

Tempted to go searching for that thread again...

 

[someotherguy]

@DerekTheGreat ,

Optimizing/modernizing the primary closed loop sensor would be something that appeals
to me, so I decided to look up what someotherguy was referencing. In the
'94 Driveabiilty, Emissions, Electrical Diagnosis & Wiring manual I found the
following wiring diagram showing both Single Wire & 3-wire Heated O2 sensors,
making for a nice comparison:

You must be registered for see images attach

Note: The factory power connection for the O2 heating element is connected to the '4WD' fuse.
(Side-note: Possibly this is the non-4WD-related thing that this fuse affected on a 2WD truck
that @Schurkey was referencing in a recent thread?)

Here's confirmation of the above with some additional detail on what all is connected to the
4WD fuse. Of interest is the "LB4 only" notation for the heated O2 sensor? Of course, a lot
of things can happen between when the manual was written and when trucks are popping off
of the end of the assembly line later on.

You must be registered for see images attach

As for splicing into this circuit, I'm from the Western Union splice, soldered & heat shrinked
school of thought. Solid mechanical, high conductivity connection first, locked permanently
with the solder, and further weatherproofed/insulated with the heat shrink. I've never had
to revisit any connection made this way.

Of course there are many other reliable, permanent connection methods out there, possibly
someone can jump in with something easier, yet will still outlast the rest of the wiring harness?

****

Anyway, hope this clarifies how GM documented the added heated O2 sensors back in '94.

Cheers --

Pretty handy, that diagram from the code 44 troubleshooting page!

Richard

 

[DerekTheGreat]

Check the 1994 factory manual wiring diagrams. C1500 or C2500LD w/5.7/4L60E had heated O2 from factory, as did most of the other models, but that one's a for-sure.

Richard

I did try to do that, but it appeared as if I'd have to download software before I could download the files I wanted. Didn't want to do that.

Special thanks to Road Trip for posting what I needed! Schurkey too. Looks like it's cool if I just snip the pink/white wire coming from my 4WD fuse & use a heatshrinkable butt-splice connector that's also adhesive lined. Or the little thing he used, don't have any of those but could get some. I've got plenty of adhesive lined heat-shrink tubing.

 

[Scooterwrench]

Only thing I could add would be to use adhesive lined heat shrink tubing to weatherproof your splice.