So all the lights coming on is normal.
But my gauges bottom out and come back up in the on position and then they do it again once I start the car.
Are the gauges supposed to do this once or twice ?
Sorry night magic I see you mentioned your gauges but I wasn't sure of this is what you were saying was happening or not

 

I found this article on the 01 astro vans.

Case 2

It's mentioning there is a single yellow wire on circuit 710 that connects PCM and bcm but does not communicate with any other device on the class 2 circuit.

The article describes very similar issues to the one I having, the only difference is I don't have any issues while the vehicle is in operation. This safari in particular, much like many of you will have battery/security light flash on while driving and gauges go wonky while going down the road.

They said they found the yellow wire on circuit 710 was intermittently going to ground due to a bad harness. I haven't found any chaffed harnesses yet but I'm still looking.

So my question to the forum is,
Do our montes have the same circuit 710 with this yellow wire. Or am I going on a wild goose hunt

 

once i shut my car down my gauges drop to the bottom. if i would turn my key to acc the gauges do not move. i turn to ON and they do a little jerk movement( its tiny) then raise to where they need to be: gas gauge is the only thing that should move to let you know how much gas you have. unless you car is warmed up then you temp gauge will raise to the current temp of the engine. but the speedometer and rpm gauge will not do anything but that tiny jerk since you are not driving the car or revving the engine. when you shut the car down they all drop to the bottom.
i wonder if that yellow wire is in the harness that you plug the scanners into?

 

The bold face type above (except the ground issue) is perfectly normal. Did you use ohm's law to convert the ohm readings to resistance? Even though the ground under the air filter has continuity doesn't mean the connection can pass adequate current.

 

So as far as I can tell my start up sequence is normal. All my lights and gauges are acting normal.
One thing though, my gauges do the little spike/jump in the on position, and then they do it again when I start the engine. Is that normal?

When I was ohming out my grounds all were good strong signals, like 0 to 1 ohm
Nothing was above one ohm for resistance.

What kind of voltage readings are you guys finding on your batteries?
I have a solid 12.85 when the car is shut off and when the engine is running it jumps to about 13-13.75 volts

 

I think it's your OBD II Port. The computer is talking to everything except it. Maybe they hit something wrong when they plugged there scanner in and now a pin for a main signal is loose or something. I'm just guessing. Trouble shooting logically from what you've told us!

 

Still throwing codes
Still no resolution
Gonna wait it out a while
Car is running fine
I will keep you guys posted with any updates

 

Can you communicate with the sdm. Those are common to get water intrusion and cause all kinds of issues, it's mount under the seat. When a module is shorted, it's all on the same data line and will cause havoc on the whole system.

 

I'm not getting any SDM codes but I will have a look under the seat tonight when I'm off work
Is it the drivers seat?
Do I have to remove any carpet or anything
Thanks killerB for the tip

 

Old Thread, But I thought I would give everyone involved a quick update.
After much searching and disassembling of electrical components of my car i came up short.
All the codes mentioned in earlier posts of this thread were still present, I had given up entirely. I wasn't going to pay dealerships or Shops for use of a tech II scanner.

Weeks later, after many kilometers of driving, i decided hey, why not throw the code reader on the old monte to see how shes doing. Well the reader came up with no codes present.

No Codes?!? Wow, it had been a while since Id seen that, I couldnt be happier. Though I never found an actual resolution to my issue, i'm happy the car has managed to resolve the issue it self

Again, I thank anyone who was part of helping me troubleshoot this problem,