For some reason the Coolant temp sensor I put in brand new isnt ohming out. I disconnected wire harness and probed the terms on CTS and it's open.
i checked the one I took off before and it ohms fine. I also disconnected short harness and it ohms good so
For some reason the new one failed right away
I never had that happen before
Im going to reinstall older one and see what happens

 

Does anyone know if a bad PCM could short a CTS?
The new one I put in doesn't ohm out.
Going across the two prongs on CTS I get open on my meter. I tried at 200 and 20K
The old one I took out that I tested ohms out fine.
Maybe it's because it was a value craft brand from AutoZone

 

Just curious, with all the mis-fire issues, have you had the ICM tested?

 

No I haven't..
The local auto parts stores don't test them so I was trying to figure out how to test it myself with an ohm meter..

 

I know my local autozone has a tester for it. They hook a harness up to it and the prongs for one of the coils (if you found a store to test it, I would ensure they test ALL the coil prongs).
Sadly, I do not know a way to test it. If you had access to another 3800, you could temporarily swap it (this part is the same in the supercharged and non-supercharged 3800, as well as the last generation of the 3800, so a LOT of vehicles interchange with it).

 

I'll have to call AutoZone tomorrow and see if they test the ICM here.
I did find an article on internet that gives step by step instructions how to test all the ignition parts and circuits!
I'm still stumped on how the new CTS was working and then it it is now open?
There are some weird things going on with this car

 

Ok my AutoZone doesn't test the ICM
but I did the test from online I found.
It checks out good!
I got another code like before PO304 Wich is miss fire cylinder 4
So I did the engine roll test.
With car idling I disconnected the fuel injectors one at a time.The engine should drop in rpm's with each inj.
They all made the rpm's drop but number 4
So that tells me cyl 4 is dead cyl..
So tomorrow I'll get a compression checker
And pull all pugs and check each cyl one at a time. Hopefully they all have equal compression with in 20% of each other's.
I think #4 is my problem..

 

Ok update!
I checked CTS today cold engine outside temp 45° it was at approx 5.35
So I started car and let it warm to 185 °
I checked CTS and it was open.. No ohms
So I decided to replace it with another..
same thing. same results..
Is it normal for the CTS to open at normal temp?
Could it be the. Short harness? I used that to check ohms on CTS. I just unplugged it on main harness side.
I also check V's on harness coming from engine PCM and it had 4V's sometimes 5V's
Temp gauge still not working.. It does move very little as key is turned on...
And fans are on..Even at start up

 

To ad to last post I checked CTS I removed from engine! And ohmed it at 57° ambient temp and it has 2.50 ohms! 2050
my book says at 58° it should be around 4450
So my new CTS is off by 2400 ohms about,..
At 36° it's aprox 7720 so it's close. Book says at 40° it should be 7280
So why when it's in car and engine warmed up to 195 ° it shows open?

 

I admit, I don't know what the CTS readings should be, but that seems a bit strange to me that at 195, it tests as open. I would think it should ALWAYS have an ohm reading.

And as for the mis-fire, compression test is a good approach. Hopefully that is NOT the issue. But but your options are getting limited. Did you trying swapping/moving the #4 injector to a different position?