New Jasper TC now 4WD light on and stuck in 4HI

[aquaman0001]

I just had a new Jasper TC put in the Suburban. Seemed fine till it snowed today. Started the truck, put it neutral and pressed the 4Hi button. Great, all seems well. But before I am out of the parking lot the Service 4WD light comes on. I pull over and put the truck in neutral and now I cannot switch out of 4Hi. Fuse? There is no response from the push buttons when pressed. Could the dash switches be bad? Actuator motor? Any suggestions is greatly appreciated.

[DaveNY]

first thing pops into mind is to check connections on encoder motor.(loose plug?) thats the last place sombody was working?

[aquaman0001]

Just went and started the truck. I was able to put it into any drive(2H 4L Auto..) and no 4WD service light. But when I start to drive it the 4wd service light comes back on and I am again stuck in whatever drive I am currently in. All the other buttons will not respond
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[aquaman0001]

Started truck and went down the road in 2wd. No 4wd service light. Great. Stopped the truck, put in neutral and pressed the 4Hi.....WTF. It worked. Will someone please explain what happens after you press the dash push button to put it into 4WD? Maybe this will lead me to what needs to be replaced.
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[DmaxMaverick]

If you are stationary, you should hear the motors engaging the gears (front and TC), and perhaps a "clunk".

However, you should be engaging/disengaging 4-Hi while driving. It's synchronized and will engage at any speed. You can engage/disengage while stationary, but it isn't necessary. When you do this, you should feel a bit of a surge or hesitation, and additional gear noise may be heard/felt. You should only have to stop and go into neutral to shift in/out of 4-Lo.

It's hard to tell what's wrong. It shouldn't complain, in either case. With the 4x4 engaged, jack one front wheel. Spin it (if you can...if it doesn't spin, it's locked in). Observe the front drive shaft. If it turns, the TC isn't engaging. If it doesn't spin, the diff isn't engaging. If it's locked up tight, you might have an issue with a limit switch, which reports to the BCM the state of the drive. This is usually an indicator of an encoder motor on the way out.

To start with, if it doesn't respond properly regardless of pushing buttons, replace the switch cluster. They are the least expensive (and easiest to replace) part of the system, other than wires/connectors. They are a known early failure item, and can be bad right out of the box. If it does respond, and you have flashing 4x4 cluster lights and/or the "Service 4WD" message, even if it does engage, replace the button cluster. It's still the least expensive part, and can cause any of the above.

[aquaman0001]

Thanks for the tip. Is the dealership the only place that will have a exact match on the cluster?
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[DmaxMaverick]

I don't know of any source, other than GM. You might try www.gmpartsdirect.com . If they don't rape you on S/H, it'll be about 1/2 dealer list.

[aquaman0001]

I know, gmpartsdirect usually has better prices than the dealership but the shipping cost is ridiculous.

[JohnC]

In their defense, I ran a business that involved a lot of packing and shipping. If you're not making much on the parts you can't afford to pay someone to pick and pack the boxes, and generate the invoices and labels, all for free. You have to cover the labor, the packaging materials and the shipping charges. Oh, yeah, and health care...