GMC 4X4 not engaging

[ryan#1]

Has anyone had any problems with their 4x4 not engaging on the newer model GMC trucks. I have a 2007 (new style not classic) 2500hd duramax.

If the truck is in 2wd and you spin the tires even a bit and then after try to engage the 4x4 it will not engage. The light blinks a bunch of times and eventually it flashes a message saying service 4wd. So if you forget to engage the 4x4 and then spin a bit on a hill or wherever and then want to go into 4x4 its a no go. If you switch into 4x4 before spinning any tires no problems.

I asked the dealer about it a few times and they don't seem to ever fix it probably because they switch it into 4x4 at the shop and it works...

Anyway wondering if anyone has had a similar problem and figured out how to fix it. Thanks.

 

[slomo]

i'll look the bulitin number up at wook tommorow for you but there is a reprogram,as wel as cleaning and rebolting the ground just under the drivers door

 

[grizzley1]

mine does the same thing, its an 05 duramax, so thx for the hint ,ill go give it a try

 

[ryan#1]

That would be great if track down the bulletin # then i can just pass that on the dealer. Thanks!

 

[Guest102]

Never had that problemon my 03 or 07 duramax. Weird

 

[johndeereman346]

the 4x4 wont engage unless you have ythe tires stopped and your foot on the brake i have found over the last 2 winters and it seems to have issues shifiting into 4 lo from 2wheel

 

[mb1]

My 07 Classic DMax has no problem going into 4hi, I've done it up to 100kph or so. 4lo is a different story, it sometimes wont engage and the gears just don't catch and make a nasty sound. I have heard that for some guys it works to engage 4lo while rolling at 1-3 mph in neutral. I don't need it really, so I just live with it. I'm not exactly a shoo in for warranty work being it's a US truck thats been modified.

 

[pete gads]

I HAVE 03 AND WAS HAVING SORT OF SAME PROBLEM, WHEN START UP TRUCK LIGHT FLASHING, OR STUCK IN ONE MODE AND WOULD NOT CHANGE UNLESS SHUT OFF AND STARTED AGAIN. MY MECH, DID A COMPUTOR CHECK AND SAID THAT THE TRANNY WAS IN SLEEP MODE. HE GAVE ME NUMBER( can't remember it) AND HAD THE DEALER REPROGRAM COST 1HR RATE. WORKS FINE NOW. HOPE THAT HELPS.