Where is the ECM on a 2007 Chevy Uplander located?

The horn going off is your anti-theft system. When you disconnected the battery, it lost its memory. Number one tip when changing batteries, maintain the power to the car with a charger, or wires to the old battery.

Reset procedure in the link

https://www.justanswer.com/chevy/7rht5-chevrolet-uplander-ls-2007-chevy-uplander-wont-crank-due.html

https://www.google.com/search?q=2007+chevy+uplander+security+reset

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Instrument Panel

https://www.fixya.com/cars/t27135463-in_2006_chevrolet_uplander_instrument

All the rest

https://portal-diagnostov.com/en/2020/07/22/all-wiring-diagrams-for-chevrolet-uplander-ls-2007/

Service Manuals

https://www.onlymanuals.com/chevrolet/uplander


https://www.google.com/search?q=2007+uplander+ignition+switch+wiring&tbm=isch&ved=2ahUKEwid79XlzNX1AhX2qnIEHUxPDhcQ2-cCegQIABAA&oq=2007+uplander+ignition+switch+wiring&gs_lcp=CgNpbWcQAzoHCCMQ7wMQJ1DYDFiEM2DtcWgAcAB4AIABX4gB4gqSAQIxNpgBAKABAaoBC2d3cy13aXotaW1nwAEB&sclient=img&ei=PHz0YZ3hK_bVytMPzJ65uAE&rlz=1C1QJDB_enCA643CA644

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2006 Impala Coolant Sensor Replacement
This may, or may not, help you locate the sensor.
The video is for a 2006 Chevy Impala that has the 3.9 v6 engine.
Hopefully one model year difference did not change the engines...

ALL TUNES-2008 CHEVY UPLANDER NO START
https://www.youtube.com/watch?v=TnIyKf0JiNU
2007 Chevy Uplander No Start
https://www.youtube.com/watch?v=PN-zlKn5KRo
Starting disabled FIXED!!! Chevy Uplander.
I have a 2005 Chevy Uplander that won't start. The problem...
https://www.justanswer.com/chevy/6jkas-2005-chevy-uplander-won-t-start-problem.html
2005 chevy uplander hard to start
http://www.topix.com/forum/autos/chevrolet-uplander/TALVQR3Q8MKI7M33D/2005-chevy-uplander-hard-to-start

images for Chevy uplander 2007 3.9 crank sensor

2007 CHEVROLET UPLANDER Crankshaft Position Sensor

www.rockauto.com/catalog/x,carcode,1433507,parttype,7196

Please check notes in each part listing to ensure the Crankshaft Position Sensor is correct for your 2007 CHEVROLET UPLANDER with a 3.9L engine.

Could be the exhaust system hitting the frame or body of vehicle when you hit a bump. There should be some wear marks where the pipe is hitting.

Where is the expansion valve located on a 2008 Chevy uplander

its not under the hood, its near the fuel tank, and charcoal canister.

I have a 2006 chevy uplander that had an abs light coming on so i took it to my local GM dealer to have it diagnosed and they had told me that the hub and bearing assembly needed to be changed, so i changed it and the light still came on. Upon further investigation i came to discover that the abs wires were frayed in two locations and that the connecters were loose i tightened the connecters and replaced the wires and now my abs light does not come on. I also discovered that i did not need a new hub and bearing assembly after all.

Hope this helps

UPLANDER 06 Elec Cont Unit (ECU); (left front of engine compartment), 3.5L.
http://cgi.ebay.com/ebaymotors/2006-Chevy-Uplander-Engine-Computer-PCM-ECM-12600928_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318QQ_trksidZp3286Q2ec0Q2em14QQhashZitem320315289651QQitemZ320315289651QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories