I've been having a minor issue with my work/plow truck. Sometimes the ESOF does not want to engage the four wheel drive. I'll press the 4WD button and the 4WD light will flash about 5 times, then go back to 2WD. It'll do this for a few times and then most time it'll eventually go into 4WD. When it goes into 4WD everything works as it should. Sometimes the problem won't act up for months, sometimes it'll happen everytime I try to put it in 4WD. Any idea on where to start? Is it bad switch, relay, or what?

 

What year? The early IFS GM front differentials had a thermal actuator, mostly reliable, but was the most common point of failure. Since you said button instead of lever, you may have a different system.

Jim

 

It's an '02 with the button, not the lever. I wouldn't be too concerned about it other than the fact that I plow with it in the winter and need the 4WD to be reliable. I hardly use the truck other than plowing in the winter and taking it where I don't want to take my F350. It gets about 4000 miles on it a year tops, but is used every few days, so the moving parts do keep working.

 

Before winter sets in I would get underneath and make sure every electrical connection to the transfer case and front diff are clean and tight. Push button systems use external electric motor actuators to shift the transfer case.

I prefer the lever system, with a neutral position, but you cant buy a truck with it anymore. With manual hubs, those are still shift-on-the-fly.

Jim

 

Thanks for the help Jim. I'll crawl under there and see whats up. I really wish trucks with levers were more readily available, but it seems nobody orders them anymore.

 

As I recall, they improved the thermal actuator in the late '90's, but it's still a thermal actuator... it may need to be replaced.

-blaine