Truck won't start after head unit replacement. *** solved ***

So I installed a new Alpine ilx-507 yesterday in my 2016 SR5 and it worked.
Today when I started the truck the head unit did not power on. I assumed a fuse or loose connection and proceeded to make 2 short trips.
Later I reconnected all the harness plugs and found a loose plug into the head unit.

Head unit works well now but denotes on vehicle information screen ODB2 error.

And now the truck won't start; it cranks well but won't start.

I attached an ODB2 scanner and it mentions a failure to communicate with the ODB2.

I reinstalled the OEM radio.

I checked dozens of fuses.

At a complete loss as to the next step.....

 

You checked all the fuses?

Even the ones under the hood?

 

Most of them in both places. Skipped ones that "couldn't possibly" be related.
Checked radio, odb, efi, ecu labeled ones.

 

Did you disconnect the battery before starting the new stereo install?

 

Yes, and when reinstalling it, and when reinstalling the OEM.

I just checked ALL the fuses in both locations, that can be pulled with the fuse puller. Not sure how to check the box shaped fuses.

Also just put charger on battery.... had gotten worn out from many attempts to start.

 

Did you check all the wiring running from the OBD2 port? It sounds like something might've been tugged a little hard if even the OBD2 tool is reporting a communication error.

 

I'll check, but nothing in the install was anywhere near the ODB2 port.

 

I don’t see any loose wires.
My scan app can connect to the odb2 scanner but can’t retrieve any info.

question- will turning the key to ON show fuel amount? The needle doesn’t move. Just curious, I know there is fuel.

 

Sounds like the CAN Bus is offline, make sure there is nothing pinched or shorted together behind the radio.
Maybe even unplug the radio and see if things come back.

If not then we will need to unhook the battery and check resistance between pins 6 and 14 at the DLC, it should be 60 ohms +/- 2 ohms.

 

Disconnected OEM radio and no start with neither radio installed.

pins 6 and 14 show 59.7

 

Check them to pin 4 and pin 16.

 

4 and 16 DC voltage shows 12.65

 

I meant check resistance between 6 or 14 and pin 4 and then pin 16 with the battery unhooked.

 

Ok, battery unhooked


4 6 .58

4 14 .6

16 6 5.9

16 14 5.8

thanks for helping with this puzzling outage.

 

Is that ohms, K-ohms, or M-ohms?

 

Looks like multimeter defaults to M-ohms, though I didn’t retake samples.

 

Just trying to make sure because if that's in ohms that would be a short.

Check the voltage between 6 and 14 and then between 14 and 4 with the battery hooked up and the key on, also see if your CEL is on with the key on.

 

Will do, thanks.
Too funny, had to lookup what CEL is. Anyway, it’s never shown up during this issue.

 

It should come on with the key on, I was kinda focused on the CAN bus since it goes to the radio.

I'll look over this all again when I get to my PC, do you have a regular key or push button start?

 

Regular key.
Nothing comes on with key ON, on the left or right display. Center info does show odo and door ajar.