4x4 Hi/Lo Lights Flashing!

[ruzztec]

I have a 99 as well as a 92 and the 99 had a prob last winter. The mechanic said that the lights were flashing becuase the 4x4 needed to be serviced. He said that the vacume hose poped off and all he had to do is reconnect it. Well now its flashing angin and I thought someone might know how to helpme locate that or another prob + fix it might be.
It just started snow today about 3 hours ago and we have 4 inches.

 

[dogfriend]

I'm confused. Its the 99 that has the flashing 4x4 lights right?

97 and later doesn't use a vacuum shift, so his fix doesn't make any sense.

When the 4wd lights are flashing, it means that the GEM has detected a problem in the 4wd system. If you have access to a scanner, you can scan for GEM DTC's (diagnostic trouble codes). This will give a better idea of what the problem is.

 

[sunbum]

Prob your speed sensor but do a search on the site, plenty of posts on this topic.