Hello all. Long time lurker, first time poster.

I had a question about a 04 Tahoe z71 I just bought. Seems like it runs higher RPM than our YukonXL. For instance, at 70 MPH, the Tahoe will run about 2200 RPM, but the YukonXL will run at about 1800. If you go 80 MPH with the Tahoe, it will be at about 2500. Just seems high to me. I think both vehicles have a 4.10 rear and 5.3L engine. Both 4x4.

Also, when I press in the tow/haul going down the road, it doesn't seem to feel any different. Could the tow/haul be stuck on (and not registering) and giving me the higher RPM. The tow light goes off and on in the dash when I push the button.

Thanks in advance for any help!

 

it sounds like one has a higher gear than another. even if the tow haul was stuck on after 60mph it shifts into overdrive. if they have the same gear I would check out the torque converter.

 

Welcome to the forum.

If they truly have the same axle ratio (u can check on the RPO label in the glove box), then I'm guessing that the Tahoe is not shifting into OD.

But 70 mph and 1800 rpm sounds more like a low 3.XX ratio. You can check by rotating a wheel one revolution and counting the number of times the drive shaft rotates.

 

you failed to mention what year Yukon... the Tahoe went to a 6 speed in '09 vs the 4 speed prior. I do not know what year the Yukon made the same change.

I dont think tow/haul kills the OD gear, just keeps you in lower gears longer, doesn't let you coast, and on mine stiffens the suspension...

the Z71 (off road) edition generally would have lower gearing than the non Z71 models as well...

4.11 i believe... there should be a stamp on the diff of what it is (at least jeep does that) it's a tag bolted to the diff.

 

the Z71 may have a 4.10 rear but I doubt a regular 4x4 Yukon does, probably the 3.73 (or simlar). like Shark said you can check the codes in the glovebox to confirm the rear end on both. That would be the most obvious reason for a descrepancy.
our Tahoe has the slow 3.42 gears but we are also around 1900 rpm at 70mph

 

Thanks everyone. I'll check on rear on the YukonXL to make sure. It is an 05, BTW. I guess I thought they both had a same rear, so worth checking!

 

From my own trial and error all the tow button does is change the shift rpm. Now again that's on mine and it might be messed up as well. But that's what it does.