I have an orange wire labeled PTO in the harness going to the ECU along the fire wall. Anyone have any idea as to what it is. Its a 99 1500 Laramie slt quad cab 5.9l auto 4x4.

 

Your truck didn'td have a PTO (Power Take Off) only 2500/3500 2wd trucks had them

 

I've got other things on this truck making me wonder. I've only had it since June 23 2018. The fuse box under the hood has relay for trailer tow, diesel fuel heater relay and fuse, 32 gallon tank. So I don't know what to think.

 

Dodge used the same everything (wiring harnesses, fuse boxes, etc) for each model. It cut back on cost and makes adding things easier. For example if you don't have clearance lights the wiring is still in the headliner. So you will find there is a lot of plugs you won't use.

 

No they didn't, Things that where optional where not in all the harnesses. If you read posts on how many people want to add the overhead console with the temp readout, You will see the wiring for this in not included. Adding wire in a harness for all trucks that didn't use it will cost more for chrysler's bottom line.

 

That's good to know. I guess I only assumed that because all my trucks had the wiring for them but didn't have it from the factory (even my third gens)