Unknown sensor (?) wire

[KVacek]

No codes. Tried clearing codes and the MIL stayed on, but still no codes.

The wire is about 6 inches long and there's nothing I can see anywhere that it can stretch.

 

[KVacek]

Maybe it was just taped off after something the original owner removed (though there's no evidence of an alarm, etc). However, an alarm guy would usually take power closer to the fuse panel and not out of some wire nicely branched out of a loom that runs in front of the pan.

Sure looks like it should go to a sensor.

Maybe I knocked something else loose in my work, though all I intentionally disconnected was the radiator fans and the MAF sensor, and they're back on. I'll look thoroughly yet again.

 

[Rocket Man]

I would start by removing the split loom on the harnesses in that area and looking at the wires inside them.

Also, if there’s a MIL there’s a code. It might not have set yet but it will. I’m pretty sure if the oil pressure sensor doesn’t get a reading it won’t start, not sure about others.

 

[KVacek]

One more DUMB thing I did...

I had to put the truck into neutral to get the front driveshaft off. Battery was already disconnected and to leave it in neutral I had to leave the key "on". No problem till I reconnected the battery and forgot that the key was on. Remembered when I went to start up maybe half an hour later. 4-year old battery was dead. Charged it and it cranked fine but no start.

What happens with a computer vehicle when the key is on while the battery is reconnected and then stays on for half an hour?

 

[KVacek]

I would start by removing the split loom on the harnesses in that area and looking at the wires inside them.

Not sure what I'm looking for. The wires are fine. The one that's got the bullet connector to the red wire is a thin black wire with no trace. Guessing 18 gauge, but stiffer than typical stranded.

 

[Blackcar]

Are all wires connected to front diff being a Denali it may be AWD which I don't think have circuit going to diff. That has been repaired at some time there is also wire going to ABS on each wheel for anti-lock brakes.

 

[Rocket Man]

Not sure what I'm looking for. The wires are fine. The one that's got the bullet connector to the red wire is a thin black wire with no trace. Guessing 18 gauge, but stiffer than typical stranded.

Did you remove that covering (split loom) off of those two sets of wires that I can see in the pics? Cut that tie strap off, and the split loom can be removed. You might have to remove some electrical tape if you are at the end of the loom otherwise just stick a tool into the split and remove the wires that are loose inside. Pull them out of the split loom and inspect for one that has a loose end. I’m thinking there might be a wire inside of that loom that your loose wire used to connect to.

As far as the ignition being on and then connecting the battery and then letting the battery die, you might have fried the powertrain control module ( PCM) which on that year 6.0 is both the engine control module and transmission control module. If you did that, you’ll have to get a replacement programmed to your VIN and then do a VATS relearn. If you have a Tech2 you can do it yourself, if not a shop will have to do it. Used PCM’s can be bought on eBay. You’ll need to get the p/n off yours. It’s under the battery in the engine compartment, it has 2 big connectors with a hundred wires going to it.

 

[KVacek]

Did you remove that covering (split loom) off of those two sets of wires that I can see in the pics? Cut that tie strap off, and the split loom can be removed. You might have to remove some electrical tape if you are at the end of the loom otherwise just stick a tool into the split and remove the wires that are loose inside. Pull them out of the split loom and inspect for one that has a loose end. I’m thinking there might be a wire inside of that loom that your loose wire used to connect to.

As far as the ignition being on and then connecting the battery and then letting the battery die, you might have fried the powertrain control module ( PCM) which on that year 6.0 is both the engine control module and transmission control module. If you did that, you’ll have to get a replacement programmed to your VIN and then do a VATS relearn. If you have a Tech2 you can do it yourself, if not a shop will have to do it. Used PCM’s can be bought on eBay. You’ll need to get the p/n off yours. It’s under the battery in the engine compartment, it has 2 big connectors with a hundred wires going to it.

Ummmm, yeah. I feared that. No Tech II, only a bluetooth OBDII reader that's pretty comprehensive but not nearly a Tech II.

Can a shop copy my PCM and reprogram another one without the vehicle, or am I going to have to get it towed?

Damn I feel like a moron. Working on cars since my first one in 65. Probably the most expensive screw up yet.

 

[KVacek]

I see places offering to program before shipping. One place is Flagship One. Anyone recommend a place to program and ship it to me?

 

[KVacek]

Did you remove that covering (split loom) off of those two sets of wires that I can see in the pics? Cut that tie strap off, and the split loom can be removed. You might have to remove some electrical tape if you are at the end of the loom otherwise just stick a tool into the split and remove the wires that are loose inside. Pull them out of the split loom and inspect for one that has a loose end. I’m thinking there might be a wire inside of that loom that your loose wire used to connect to.

As far as the ignition being on and then connecting the battery and then letting the battery die, you might have fried the powertrain control module ( PCM) which on that year 6.0 is both the engine control module and transmission control module. If you did that, you’ll have to get a replacement programmed to your VIN and then do a VATS relearn. If you have a Tech2 you can do it yourself, if not a shop will have to do it. Used PCM’s can be bought on eBay. You’ll need to get the p/n off yours. It’s under the battery in the engine compartment, it has 2 big connectors with a hundred wires going to it.

HOW can I verify a bad PCM ??

I have NO codes. Nothing, though the code reader seems to be scanning for codes and I get other gauge indications on the scanner (voltage, speed, G's, etc)