They dont give you a schematic of the ECU only the wire color code and what pin it goes to on the connector plug.
Propane is fairly easy to set up on a vehicle. It takes me about a day to do a full dual fuel system install.
Dual fuel is when your retain the full gasoline system and have the propane system all integrated with it down to a simple switch under the dash that allows you to switch between the two on the go.
The propane system is fully compatible with bottled hydrogen but your engine is not!
For hydrogen you need very high compression and extensive engine work to get any good power and efficiency out of it. Without it your power is horrible and so is the fuel mileage!
But once your engine is set up to run efficiently on hydrogen it cant run gasoline ever again. It however will still run on propane though with a slight detune.
On a stock gasoline engine you will get typically poorer mileage and less power with propane, But not always. My Ford F250 has the Triton V10 engine and in order to meet emissions standards the factory has it so horribly detuned that propane is actually slightly better for power and near dead equal for mileage.
You do have to realize propane is only around 4.1 pounds per gallon and gasoline is around 6 pounds per gallon too. But propane has higher BTU's per pound than gasoline.
So comparing miles per gallon is not an accurate comparison measurement. Cost per mile is and thats what your going for, a cheaper operating cost.
A full propane conversion requires your engine to have the compression raised from the stock 9:1 ratio to around 11:1 for best power and efficiency. Plus propane has a smoother burn rate and a bigger more aggressive cam will run smoother on propane too!
I built a Ford 460 cubic big block to run on propane some years ago and it got a typical 14 - 16 mpg (interstate driving at 75 mph) in a 1985 heavy half ton F150 and was pushing 400 hp! It rarely went under 10 mpg even while towing double its own weight too!
My 1999 F250 does about 10 mpg ( gas or propane) highway and about 4 -6 mpg (gas or propane) towing the same load on the same trailer with less Than 275 hp.
When the bank loan for it is paid off the 460 is going in the new pickup!
I have run three pickups of my own now with propane and have well over 150000 miles of personal driving experience with it and every pickup I will ever own will have propane as the primary fuel!
I have also did a number of dual fuel conversions for others and they too have had great things to say about the cost per mile being better and the engines do not wear out!
Some say they see slight power losses on propane some dont.
I typically go 12000 miles between oil changes and the oil still comes out clean! Clean enough in fact I reuse it in my tractors!
Beware of the propane myths though!
Lean burning does not hurt your engine and valves. Your modern engine has hardened valves and valve seats and that has been industry standard for 40 plus years now.
Lean burn just bogs and looses power it actually will cool an engine down during extended bogging and the exhaust temperature will drastically reduce too!
It pretty hard to burn up something that cools down!
Lean burning gasoline is what burns valves and does far more damage!
like most alternative fuels there are many detractors that will tell you bad stuff that they heard happened to a friend of a friend of a friend and therefore must be true!