Need some help diagnosing a 2001 Pontiac Aztek

[TollKeeper]

Woah! 1 of 2 built!!! I'm curious what makes it unique?

That's more rare that the 1969 COPO "Cameros" LOL

Thats actually easy to answer..

This is a GT, which were only made in 2001
This one is in Citrus Green, which you could only get if you ordered it, and only produced for 2001
This one has 4 leather bucket seats in grey, only produced for 2001
This one has HUD (heads up display)
This one has factory Pioneer amps and speakers
This one has the factory hikers package
This one has the rear removeable cargo tray
This one has the factory campers package (tent, mattress)
This one is AWD
This one has the rear air suspension
This one has the sun and sound package, with the sun package deleted
This one has leather door inlays
This one has the rear seat entertainment (allows the rear seat occupants to plug in wired headphones and listen to a alternate radio station or cd)
This one has the factory rear cargo cover (extremely rare) (a piece of fabric that ties into 6 anchors)
and a few other things...

And yes, it has the cooler too.

Edit: I have also added a few rare items from its kissing cousin Buick Rendezvous. Rear seat foot rests.



I recently took out the Buick Rendezvous Navigation unit in getting it ready to be sold. Installing it was a wiring nightmare, as the VSS wire is needed, and is not in the stereo wiring harness.

Edit2: Added to the list above

 

[strutaeng]

Oh, another thing is a wiring diagram is a must on these types of issues. I highly recommend you get the AllData subscription to download all of the wiring diagrams. I think it's like $20 for a monthly subscription. But it's really worth it even if you are selling it.

Often times multiple sensor wires are shared on circuits and that will help you pinpoint problems. A wire not making good contact such a ground is often a common problem. Worst case if you have to run a new wire from the ECU to the sensor if you determine it's the problem but can't locate the location of the fault.

 

[OR VietVet]

If I am remembering correctly, inside the air filter box.

Edit: I assume you are meaning the PCM?
View attachment 406340

Yes, PCM....I was wondering how exposed it is. Sometimes, like @Fless said, the connection can be cleaned by unplugging and plugging back in. Check any wiring that you can get your hands on, leading to it. Again, any grounds. The intermittent part of this problem sure points to something like that. The CTS is another good recommendation. It tells the PCM the engine temp.

 

[TollKeeper]

Let me throw this into the mix (it just popped into my head)

About the same time this all started happening, maybe a couple months before, I was also having a random battery light on the dash. Battery was still charging, and the battery itself was good. It was another scenario of pulling over, shutting the truck off, and restarting it, and the battery light would turn off.

I originally thought it was just the alternator, and pulled it out (a nightmare in and of itself), and had it tested. Tested good. Also had the battery tested, as you have to pull it, to pull the alternator, and it was good.

 

[OR VietVet]

While I have watched and even tested starters and alternators on the parts stores test equipment, I have never trusted them as much as testing the components on the vehicle.

 

[TollKeeper]

While I have watched and even tested starters and alternators on the parts stores test equipment, I have never trusted them as much as testing the components on the vehicle.

Did that too..

Alternator Peak amperage was well within spec of OE amperage of 125amps at 117amps sustained duration, peaking (spike) during initial power up at 155 amps.

Battery tested to 87% of its duty cycle 630amp

I have since replaced the battery, it now has a 800amp

 

[Marky Dissod]

This is starting to sound like more than one wiring issue.
It looks like the sensor usually works normally, then temporarily takes a break.
It does NOT look like it's biased to favor one direction vs another.
That looks to me like wiring ...