4WD stopped working ??

[srx70024]

The 4WD on my 95 K1500 suddenly stopped working. I checked the fuse and it is fine. When I pull the lever into 4WD, I can feel it shift in the transfer case, but the front axles don't seem to engage. The light on the 4x4 indicator on the floor doesn't come on either. Any suggestions on how to trouble shoot this ?

 

Much thanks.

[westex39]

Sounds like the front axle 4WD ingagement actuator has quit.

There has been a lot of failures with these units.

The earlier actuators were a thermal type. They had electrical heaters

that heated a thermal expansion pill and this engaged the front

axle. The trouble with this one was if it was extremely cold or the

front axle was buried in a snow bank it would not heat up enough

to engage.

Later models were electric and were to correct this problem.

There are some vacuum actuated types in the after market.

You can do a search and I'm sure you find them.

 

Hope this helps,

 

westex

[Bob G.]

GM used a thermal actuator for the front axle from '88 to '97. I think they went to an electric actuator in '98. 4WD workd great in the summer when I didn't need it but was slow to actuate during VT winters! I swapped the thermal actuator for an electric one in my 88 GMC and then it was a lot more reliable.

 

Bob G.

[mdub]

Yep, the electric motor actuator began in '98. Dealers have an update kit available, or will install it (for a fee). It's more expensive than just replacing the gas-actuator, but it's worth the extra $, at least if you plan on keeping the truck.

 

BTW, when I had the update installed on my '93, I believe the parts and installation ran just over $100.

[Marklark]

I just had the 4wd quit working on my 95 2500, but the light does come on showing the front is engaged but it isn't. Do you guys think this could be the thermal actuator as well, or might it be something internal?

 

And does anyone know how to tell the difference between the front IFS GM differentials? I know the 8.25" and 9.25" front IFS have a different spline count on the axles, but I was hoping I could identify it before I tear into it.

 

for the record, it's a 1995 K2500 Silverado w/ 6.5L Turbo Diesel, 4 speed AT, 3.73 locking rear