Did you check battery resting voltage?
The battery is a storage tank & the alternator is a power plant!

 

when i first got my H2 i noticed that my blinkers would stop blinking and just stay on left or right did not matter on a really cold day. it was the relay in the turnsignal module had arthritis it would bind up on cold days. a whack would get it going again but its location under the dash is awkward to get at it for a good whacking.

 

Yep the battery is the storage tank... But when the Alternator is pumping out 14.5 volts at the battery terminal ...that's 14.5 volts to juice the entire electrical system.
So no fade at at 45 MPH on any electrical system unless its Farked up. When I tap tap on the **** and the full brilliance comes back it ain't the battery.

 

Alternator Voltage Output vs AMPERE Output.
"Tap to restore"?

I would expose & clean connector/contacts TO RESTORE!:

 

CRC is a Copy of this... I've been using this professionally in the Pro Audio Electronic repair industry for years. Besides... Battery Contacts and terminals were cleaned about two months ago as I added a Mice Deterrent device in the Vette and the H2. Deoxid-D5 was used on both. No conductivity problems all Lights are bright and all electrical functions working as designed....Except once in a blue moon a few taps on the 4WD switch. There is definitely a cold solder joint for the L.E.D. Power..

You Tube

 

There's a TSB from GM I posted years ago that shows warranty returned control switches investigated was due to fluid intrusion from various spills fluids liquid air fresheners leaking into the switch and after cleaning restored working perfectly.

 

Thanks...Very Good Info. I also should report that after a tapping and rotating the switch and excessing all functions of the 4WD Hi & Low as well as Pumping up the AIr ride and dropping it back to normal ride height that the 2 is working normal and providing me with great sadistfaction as I run the Brick down the interstate.