4x4 not switching on - Diesel Forum

00350 · 11-09-2009, 06:37 AM

I turn on the switch for 4x4 high or low. Nothing happens. tried manually switching at the wheels, nothing. I checked fuses under steering column, changed 1 fuse. nothing. Could it be another one under the hood? For truck in sig. I don't have a owners manual so, I don't know what fuses control what components. Thanks in advance.

reddgz · 11-09-2009, 07:07 AM

I had the same problem with my 1999 F-350. I found a old post here on this site that helped alot. The problem is the GEM module had a problem with the software. The post said to pull fuse 15 and you take the power off that module and when you power it back by putting the fuse back it resets the module. You can replace that module but I am not sure what the cost is.Look
in the archives and you can find that old post. I just reset mine when quits and do not worry about it.I hope this helps you.

**woodnthings8** · 11-09-2009, 09:39 AM

If you need a owners manual go to Motorcraft.com technical resources

Can you hear the transfer case motor shifting? You may have to crawl under the truck with it off and have someone cycle the switch.

Look at fuses 59 (30A), 27 (15A), & 34 (10A)

Also have you verified it is not engaging, or are you just relying on the light on the dash?

nikkijax2003 · 09-09-2011, 10:40 AM

I have a 2000 f350 and the 4x4 light flashes as I'm going down the road. what could this be?? Also the same time this started the A/C started switching from Max A/C to defrost back and forth and will not cool the truck. How can I fix it????

Oneof6 · 09-10-2011, 06:27 AM

Sound like a vacuum pump problem.