Hey all!

New member and dug through pages of posts on the search function but not seeing this issue from anyone else.

I’ve never owned a full-time 4WD truck before so I’m a bit confused about something. I was replacing my oil pan gasket in my H2 a couple of weeks ago and noticed something strange that has me worried.

I have a steep driveway (9% grade) so I’m cautious about pulling driveline parts when I went to pull the front axle to address the oil pan leak. I chocked the wheels, put the transmission in park, ran large ratchet straps from the rear wheels to the frame just in case, and parked my other truck behind the H2 in the worst case event that it rolled…at least my other truck would keep the H2 from landing in my neighbor’s living room. Fresh rear brakes and parking shoes but haven’t adjusted yet. Anyways, I unbolted the front driveshaft and the H2 seemed like it rolled a little.

Cut to a few hours later when I went to reconnect the front driveshaft and the bolts didn’t line up. So I put my girlfriend in the H2 and told her to start it and pull up a little bit so I could line up the bolts in the front driveshaft. She put it in gear and it didn’t go anywhere. Odd! I looked underneath and noticed that the front driveshaft was spinning but rear driveshaft wasn’t spinning.

Long story (sorry!) but would you all think this is a bad transfer case? The H2 has always driven oddly (feels like the front end pulls more that the rear under acceleration) and seemed to be underpowered. This seems to lend credence to it only moving in FWD in the 6 months that I’ve owned it.

Thanks for any advice! Looking forward to being a regular poster here.

2008 H2 SUV Luxury model
6.2L
>130,000 miles
all stock on 35” M/Ty’s

 

Have you tested with all wheels off the ground on level ground, Or cycling the transfer case preferably on dirt loose terrain?

 

Thanks for the reply. I can’t get all four wheels off the ground due to super steep driveway and steep road in front of my house. All friends and family seem to have a steep driveway, too. Only option seems to be to rent hourly space at a shop but that’s not ideal. Maybe have to park in a Wal-Mart parking lot in the middle of the night and jack it up haha.

But wouldn’t disconnecting the front and rear driveshafts from the differential do that same test? Or are you thinking it’s the rear diff? I would think the driveshaft would still spin if it was a bad diff. Or the driveshaft would lock up completely if the diff blew up.

 

Oh I missed your second question. I guess I could find some dirt and test t-case function. I did test it when I bought it and again a couple of months ago on asphalt but if I recall correctly that was just to test engagement and straight line driving at 5mph-10mph to make sure of no noises.

 

https://www.hummerforums.com/forum/h...t-shaft-35312/

read through this one (H3 though), I don't have first hand knowledge so tried to find the info

Neal

 

Interesting read. Thank you for that. A couple of notes below based on that thread.

- I have no codes. Scanned with Autel shop level scanner. Although I’m still learning this scanner so I could be missing something.
- I disconnected the front driveshaft at the diff (not at the transfer case) but never drove it when disconnected technically, so the front differential never moved…isn’t that where the computer would notice there is a problem and throw a code? Just put the truck in gear and the front shaft spun for about 20 seconds.
- I have not noticed any noise from underneath. Just typical front end popping and have Kypronite package coming for that.

Is there something in the t-case that could break or come apart that engages power to the front driveshaft but not the rear driveshaft?

 

The ECM should have seen the speed sensor at the trans output shaft indicating a signal but no signal at either the front of rear which in my opinion should have set a code.

I don't know the answer to your question about the transfer case being able to apply torque to the front and remove it from the rear, being 4WD and not AWD leads me to believe that torque is equally applied to all wheels.

with the front and rear diffs unlocked i would think that at least one of the wheels front and rear should spin, I don't have a 100% positive answer on this.

I would think that the transfer case could break in a manner that would allow the torque to pass to the front and not the rear.

Neal,

 

Thanks for the reply, Neal. I agree about the output sensor but I wonder if the ECM didn’t store it since it was only a few seconds of running without the front driveshaft connected. At this point, I think we have ruled out differential and transmission issues. Which leaves t-case, sensor, or 4WD dash switch (pretty sure that’s not it since it’s full time 4WD but just a guess).

I hate to throw parts at it but I may order a rebuilt transfer case and toss it in and see what it does. That’s an expensive part to throw at it but this is our overland camping/beach truck so I don’t want to break down in the middle of nowhere.

As a Hail Mary, I’ll see if I can find a place to put all four wheels in the air to see what it does. I’ll report back with those findings but still open to suggestions.

 

You are missing something. That is a very simple test.

Find a loose gravel or sand road. Boot the truck. See if back tires spin or front tires spin. That is where the power is going.

 

if it were me I would call around and talk to the local dyno shops, they will have experience with this type of issue as they will have to do something if they don't have an AWD capable dyno which most shops don't, also any 4 WD shop may have answers to your questions.

Neal