29th Jun 2010, 22:17

2001 GMC Yukon XL with 211,000 miles. I have recently replaced the mass airflow sensor and both fuel pumps.

After driving on the highway for an hour or more and coming to a complete stop and starting again, there's a sort of "hard shift" that occurs with each upshift. It feels like a "lurch", or like I'm driving with a teenager who doesn't know how to shift a standard transmission.


1st Jul 2010, 19:36

'02 Z71 with water in rear cargo area... after reading various comments, I also found the famous "black nipple", which is where the rear A/C drains. I removed this small piece of rubber and approx 1/2 gallon of water drained out. What a large amount damage for such a small part. I am still working on finding a front drain, as I also have wet carpet in the front passenger floor after running the A/C for a long time.

22nd Sep 2010, 20:14

Just wanted to let you know what I came across in my 2003 Tahoe with the wet carpet in the front passenger seat floor. The carpet was only wet when it rained. I took it into the local shop and they found the water was getting in through the XM antenna on the roof.

3rd Oct 2010, 22:55

I have a 2003 Yukon SLT.

My problem is only the drivers side floorboard is getting wet. Where should I check for clogs? My husband is disabled and this has been driving me crazy. Could it still be this black nipple in the right rear causing this?

Thank you.

11th Apr 2011, 15:12

Same issue here.

8th May 2011, 05:44

Mine is also doing same thing, so I was going to get the windshield removed, but the glass company told me it could be the fresh air vents leaking, so I'm going to go get that checked next.

8th May 2011, 07:02

Having the same problem. Is the little black nipple the cause for driver's side being soaked? Please let me know, or I'll go back to a Ford, and this one is for sale. I was told that it could be my wind shield, because of the leak running down my rear view mirror, puddle on the dash, or fresh air vents not closing properly, needing to be cleaned out. I don't know. Help.

11th May 2011, 01:43

You can unplug the ABS sensor under the driver seat. This may take care of your problem.

9th Jun 2011, 20:19

Thanks for the advice. I have a 2002 GMC Yukon Denali XL that started leaking water into the cargo area. I read this post and found the plug. I used the dull end of a wooden kabob to poke up in the plug, and it released a lot of water for about 30 seconds. I think this fixed the problem.

7th Sep 2011, 14:15

91 Yukon wet passenger side, but second seat floor worse. Nipple was clogged with mud, used a wet/dry vacuum with tape on hose to restrict air volume. Worked great. My drain was behind left rear wheel in front of the A/C lines. Approx. a gallon or more water came out. I did not replace nipple, felt and look good.

2nd Dec 2011, 12:46

I work at a shop and see them all the time.

12th Jan 2012, 13:07

If you look at the bottom on your dash, you'll see a rubber grommet that has wires running to the engine compartment. That rubber grommet might not be in its track correctly. I have a 03 Envoy, and had a security system installed, and they ran the wire from the horn thru that hole under my dash, and they didn't push that rubber grommet back in tight, and when I washed my truck one day, I noticed water around that grommet, so check that out; hope it's the problem.

9th Apr 2012, 14:49

I have a 2001 GMC Yukon with a stalling issue while driving. You will driving along and the battery light comes on and the engine dies, then it starts right back up again. Talked to one person about it, they indicated they had a similar issue and they thought it was a security relay shorting out. I have looked in the owner's manual, and cannot find a security relay, or if this is a likely cause for this problem. Thanks.

17th Sep 2013, 08:54

That gunk is the auto dimming fluid. Either ya mirror was cracked or it just wore out. I have an 01 Denali, and I have the same problem. Just get a replacement mirror with power, minus the auto dim.

Hope that helps.


5th Dec 2013, 04:14

I had this problem on my 2005 Yukon Denali XL. It ended up being the corrugated rubber housing that connects the body to the door. This housing contains all the electrical wiring that runs from the body to the door. During a moderate to heavy rain, water would be channeled along the upper driver's door seal and would drain right on top of where this connects to the body. You can remove the sill plate and the kick panel, and place a hose with running water right over where housing connects to the body to test this. After a moment or two, if your water leak is there, you will see water draining inside the vehicle. Give it some time, because you can't directly see from the inside the whole area where the housing is connected.

Once I verified this with my vehicle, I let it dry completely before proceeding. I then pulled the housing off, applied a generous amount of 3M sealer/adhesive and reconnected the housing (it snaps back into place). I let it dry for several hours with the door open to allow the housing to remain as flush as possible to the body. I believe at every ten minute interval I reapplied even pressure on the housing where it mounts to the body so that the adhesive would cure with a solid connection to the body. At about the 45 minute mark, I gently cleaned up any excess adhesive that was pressed out. I continued to apply pressure every 10 minute for 3 hours. Not the most fun. After this, I water tested it and the leak was fixed. It's been a year, and no more wet floor. I hope this helps.

19th Jul 2014, 02:43

To your problem, I would try changing the crankshaft position sensor. It is located behind the starter. Just pull the bolts on the starter and pull it out, and you will see it in the side of the block with one bolt holding it in place. I had the same problem recently.

19th Aug 2014, 21:15

Wow - you are the "king" of the world with this solution.

My 2002 Yukon XL Denali has been wet in the back rear area every summer for the last four years and my trusted mechanic couldn't fix it - but you could!!!

Many thanks - Stuart Herder, Alexandria, Virginia.

25th Mar 2015, 18:54

What/where is the sill plate?

30th Jun 2015, 17:18

Have had this happen a couple of times. The problem is the drain line located at the rear of the vehicle. The drain is underneath and at the far rear passenger side. The drain is plugged, causing the water to back up into the vehicle.

29th Jan 2016, 01:56

I have 2002 Yukon XL (SLT). When driving, the driver's seat goes down, and even with every adjustment it's still going down - I added more foam, YET IT'S STILL GOING DOWN.