2000 LT - 4.3 - auto trans - 156K miles.

Symptoms (not sure if any of these are related, so I'll list them all):

Has always had a loud "rattling" noise under the hood, mostly when accelerating from a stop - lasts just a few seconds. Could never really pinpoint where it's coming from.

Also, ABS lite would come on intermittently, and at the same time, the speedometer bounced around like crazy (wheel speed sensors replaced not that long ago).

4/15/11 - took it in for LOF and inspection - all appeared fine.

Drove it 2 miles...BATTERY lite came on. 'Barely' made it back to the shop on battery power...died in the shop parking lot (whew!) Shop installed reman alternator.

Drove it 2 miles...SES lite came on at approx 2500rpm. Code shows faulty MAF sensor. Shop cleaned MAF sensor, but believes it may be shorting out. I'll concede...the MAF sensor is probably shot.

4/18 - 1. Trans slips like crazy...in all gears. Can barely get it to 25mph. 2. ABS lite comes on, and speedo doesn't move. 3. Bizarre "grinding" when brakes applied - almost like the ABS is activating.

NOTE: Trans was completely rebuilt approx 3 years ago.

I've searched all over this forum, and read lots of posts that mention that trans probs are often actually engine probs.

Could the fauly MAF sensor be causing all these other (trans / ABS / speedo) problems???

Thanx for your help.

 

The first post in the thread might help a little.

https://blazerforum.com/forum/engine...learned-53410/

 

Wow TZ, that's a post to end all posts! Thanx!! - Great Job.

Based on all that, I'm leaning towards a VSS - seems like the most likely thing to cause the speedo to stop working. When you say "easy fix"...how easy?

By the way - where 'bouts in NE are ya? I lived in Bellevue from 1986 to 2003 - then moved back here to NY. Go Huskers!!!!

 

And another thought...

Will a bad VSS cause the MAF error codes? As I said, my mechanic cleaned the MAF sensor, but when the code reappeared, he said he believes it's shorting out (but I don't think he knows for sure).

In the last hour or so, I've done a ton of reading about the VSS - $23.99 at Autozone...and looks easy enough to switch out (1" socket)...may just give it a try.

 

Quick update...

Tonite, I removed - cleaned - re-installed the VSS. It didn't actually look that dirty. I took an emory board gently to the contacts in the sensor, and brushed the ones in the plug as best I could. (side note: after I put VSS back in, the battery had drained considerably - had to jump-start it. Any idea what that's all about?) ...anyway...

No improvement (rats!) Speedo still jumps around, ABS lite came on (steady), and, when I start off in D, seems like it won't go into 2nd - and if it does, it often slips out and motor races (and I accidently overheated it - double rats!!)

Oh well. From all that I've read, I'm still looking at the VSS as the culprit. 'Suppose for $23.99 it's worth installing a new one. Maybe tomorrow if I can find it in stock somewhere. P.S. I read somewhere it's a 1" hex - actually, it's 13/16"...at least mine is.

Still curious if a faulty VSS will cause a faulty MAF sensor code.

 

Success!!!! Installed new VSS (took about 5 minutes) - all (well, most) symptoms gone...ABS lite gone, shifts fine, brakes feel fine, speedo works fine. Not bad for $24.00 and 5 minutes!

Gotta give a huge THANX to the experts on this forum (too may to mention). I read dozens and dozens of your posts, and I never would have figured this out without your expertise. Please continue to help us wanna be wrench-turners - it's much appreciated.

Truck still runs kinda crappy...bit of a hesitation. I think the MAF sensor is truly shot. And still has the knock/rattle/whatever under the hood...still not sure where it's coming from. Almost sounds like a loose heat shield, or shroud, or ???

Anyway...thanx! again for all your help.

 

I had a motor mount break on mine and it made a loud noise under the hood when I took off from a stop.

 

I'm in Lincoln.

Glad to hear you got it. I'm also glad to know that the VSS can screw with that many other things. It's insane how much one part can affect another. That's why I started that thread.

 

Thanx! That's definitely the type of sound. Sort of a knock - but not a low-octane knock. More of a rattle/knock. And it only does it for a second when I start it or when I accelerate from a stop. Mechanic (who I'm starting to lose faith in) thinks it's in the lower end of the engine. However, there's no other symptoms, other than the knock. I will definitely take a look at the motor mounts (and possibly start a new thread).

Thanx again.