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Disconnecting and capping the IWE vacuum lines will keep the hubs locked and engaged constantly. It does not mean that the vehicle is always in 4wd/AWD all the time. The transfer case can still be in 2wd mode and thus not send pwr to the front axle. Keeping the hubs engaged all the time would, as you mentioned, possibly reduce fuel economy.
I’m not sure about that.
This. That plastic junction is no way the weakest point in the system to fail like that. A connection will likely fail or uncouple before that part would burst in that manner. VERY SUSPECT. Most warranties don't cover coolant hoses because right hoses dry out and leak over time but I'd argue this is NOT wear and tear and not a "hose."
I read the TSB again and it does seem very vague and possibly interpreted different ways depending on the tech. I wouldn't worry too much about the vacuum lines being capped and the IWE's engaged all the time. The difference in fuel economy would be negligible.I’m not sure about that.
For our vehicles which do have a 4A option, the TSB instructs to skip to step 4.
I had the IWE failure and my service paperwork states that they removed the vacuum lines and capped, referencing this TSB. I questioned it at the time as my paperwork said something to the effect of “customer should be aware that vehicle will operate in 4A all the time now”.
I understand that is not 100% accurate, just that the hubs are engaged 100% of the time due to the absence of the vac system.
Here is a link to my original thread.
