97 Expy EB A4WD works but not 4H or 4L

[Freds001]

Hello all,

Hopefully someone can give me some guidance. I have an 97 Expy EB 5.7 with 183K miles and I'm have an issue with 4x4. When I move the 4x4 switch to A4WD the light comes on and everything seems to be ok. A4WD works as expected. I tested this in loose wet dirt and the front wheels did engage. When I move the switch to 4H or 4L I hear a clicking sound from behind the dash for a few seconds and then nothing. The 4H or 4L lights to not come on and 4H or 4L do not engage.

Could it be the shift motor?

Thank in advance for any assistance on this.

-Fred

[RickMN]

The clicking is coming from the transfer case shift relays. To shift into 4H or 4L the computer has to see the following conditions:
1) Vehicle speed at or near 0
2) Foot on brake
3) Transmission in neutral

The transmission range selector is a known problem on these vehicles and can cause all kinds of problems. Before you start replacing shift motors, test the TRS first. You'll need an alldata or mitchell test procedure to do that.

ALLDATADIY.COM - Do It Yourself Automotive Diagnostic & Repair Information
Mitchell 1 eAutoRepair - Do-it-Yourself Repair Information

[Freds001]

Rick Thanks for the reply!

When you say range selector are you talking about the switch inside the vehicle where you select AWD, 4H and 4L? If so I've already had that replaced. I'll check the links in your post and see what I can do.

-Fred

[vahid]

I have encountered the exact same problem with my 98 Ford Expedition. I wonder if you ever found a solution to this problem. Thanks