Speedometer doesn't work and transmission doesn't shift gears.


Asked by Nov 25, 2011 at 07:33 PM about the 1999 GMC Sierra 1500 SLT 4WD Extended Cab LB

Question type: Maintenance & Repair

The speedometer stays at 0 all the time.  When the transmission is in drive it won't come out of 1st gear.  Reverse works fine, and if I manually put the transmission in 1st or 2nd it works fine.

1999, Auto 4wd, automatic, 5.3L

53 Answers


Vehicles transmission output speed sensor faulty

50 out of 50 people think this is helpful.
Best Answer

I replaced both output speed sensors, and also swapped them around with the old ones, no luck. This problem started after I removed the transfer case to install the wear plate and replace the actuator motor, not sure if that has anything to do with it. The 4wd works fine. Thanks

24 out of 24 people think this is helpful.

It's Vacume or electrical is your problem or passing gear cable.If the passing gear cable is broke,unhooked at the throutle body or unhooked inside the transmission would cause that as well.Yep,Vacume could be if your 4wd works under vacume hoses or lines.If your 4wd is electric .You either got a vacume line crossed/wrong.Or leak in a vacume line or unhooked.It's not a speed sinser.Transmission Shifts either from Vacume or electrical.Sounds like to me from playing around with the transfer case you made a mistake.

14 out of 14 people think this is helpful.

2003 Sierra-My truck is doing the same thing- speedo reads zero and won't shift out of first. I cleaned the MAS, replaced shift sensor, made sure trans fluid was full, disconnected and reconnected the battery, and now I am thinking of replacing the stepper motors for the speedo but don't think that covers the shifting issue. ANY HELP welcome!

58 out of 58 people think this is helpful.

vehicle speed sensor,on the rear of the transfer case ,if you got no speed o your truck wont change gears

39 out of 39 people think this is helpful.

I replaced the vehicle speed sensor VSS then unplugged the vehicle speed sensor buffer VSSB (a 3 inch square flat white plastic sensor box) located behind the glove box, I unplugged it and waited 5 minutes before plugging it back in. I also pulled the brake fuse and did the same thing, waited 5 minutes then plugged the fuse back in. The result was successful, the tranny and speedometer work correctly now!

41 out of 41 people think this is helpful.

I did what you said but n luck

5 out of 5 people think this is helpful.

replaced the vss then unplugged the buffer waited 5 minutes then pulled the brake fuse and waited 5 minutes but no luck transmission still not shifting and no speedometer.

7 out of 7 people think this is helpful.

same for me no help at all

2 out of 2 people think this is helpful.

check the ignition switch harness for power drops across the white wire and the pink wire... it is a know problem for the harness to lose power there and causes loss of transmission shifting along with instrument cluster failures.

8 out of 8 people think this is helpful.

My 2000 Tahoe LT 4×4 has that not changing gears issue. Put it in drive - nothing, go to 1stthe and it grabs, you manually shift it, works great, even drops down gears and then changes great. The main problem is after I manually shift it, I come to a COMPLETE stop, it goes right into basically neutral, but if I don't COMPLETELY stop it keeps pulling. Once that happens, I have to manually shift it out again. Does anyone have an idea of what themayis be? issue

12 out of 12 people think this is helpful.

its more then likely the seo ign 10 amp fuse in the fusebox next to driver door the fuse looses power causing instrument panel failure and transmission goes into a nuetral state

9 out of 9 people think this is helpful.

You said check the ignition switch harness for voltage drops I think that could be my problem because when I check the buffer voltage I only get five volts at the speedo buffer I thought I was supposed to have at least 12 volts is that correct? Do I possibly have a bad ignition switch ?

18 out of 18 people think this is helpful.

I just replaced my trans in 01 Yukon. I'm having the exact problem originally stated by dfrinzi. speedo not working and won't shift out of 1st in od but I can manually shift from first to second but not 3rd or fourth. Jw if this problem was resolved and how to go about it thanks.

42 out of 42 people think this is helpful.

Speedo sensor in transfer case I replaced it now it shifts fine speedometer works like it should and I haven't had any other problems

3 out of 3 people think this is helpful.

I had similar problem and mine turned out to be the safety neutral switch.

4 out of 4 people think this is helpful.

I retract my last statement worked good for almost 2 weeks then started acting up again I'm at a loss

5 out of 5 people think this is helpful.

I found a TCM fuse (10) under the hood that was blown. Was hard to tell for certain but I replaced it and the speedometer and transmission are working properly now

8 out of 8 people think this is helpful.

I have a 2005 Tahoe and my speedometer and gas gage doesn't work gas gage stays buried over full and speedometer stays at zero any ideas?

10 out of 10 people think this is helpful.

Speed sensors on the top side of transfer case, one or the other is bad or unplugged

2 out of 2 people think this is helpful.

I have no power to the 10 amp Trans fuse. What color wire at the in essence which supplies the power to that wire? 95 gm 1500 4x4

11 out of 11 people think this is helpful.

ignition switch damn autocorrect

4 out of 4 people think this is helpful.

just replaced the trans cooler lines due to a leak and now my 02 trailblazer wont shift and speedo not working all the time

19 out of 19 people think this is helpful.

I replaced my ignition switch and problem was solved I wasn't getting 12 volts to the speedo buffer behind glove box

7 out of 7 people think this is helpful.

I've got no speedo and had 2,3,4 but no 1st. Took it to tranny guy who scanned it and cleared codes, now only 1, and 2 manually like it's in limp mode. My vss is good, ignition good, but my tccm is corroded. Could that be the whole problem. 2001 s10 zr2

6 out of 6 people think this is helpful.

Speed sensor

3 out of 3 people think this is helpful.

I am having same problem 99 tahoe abs light comes on speedometer not working could it be my ignition switch harness?

17 out of 17 people think this is helpful.

I'll try the ground behind engine passenger side in wire harness thanks Desmon Cross the man I say...

4 out of 4 people think this is helpful.

Hello everyone , i goth a gmc sierra 1996 4x4 with 75 000 km. I have a problem about my gear when i shifted with it. When i put the gear on (regular) the trunk going in front like the gear (Drive)... If i put the gear in (reverse) i goth nothing... If i push some gas when im in (reverse) the motor sounds like overload .. Do you think is the cable ? Or the tranny ? Or a sensor ? Or the neutral switch ?


It "AIN'T" the speed sensor. PERIOD!!!!!..... It "might" be in the circuit that comes from the speed sensor or one of the parallel or series circuits that the speed sensor is also interconnected with..... But in more than 95 percent of the cases that have been brought up in any of these forums thus far, replacing the speed sensor "DID NOT" solve the issue..... I'd be willing to bet that anyone who encounters this problem will find the solution only through tracing ground connections within the harness..... Codes thrown in one instance where it says that the speed sensor or one of the temp sensors, or the IAC, or the map sensor is the cause, will only pop a different code for another sensor when you replace the one that shows bad..... There is either a bad ground or a short to ground somewhere in the wiring harness..... Good luck finding it, cause in most vehicles where all the sensors are connected to the ECM or PCM, all the sensors are interconnected within the ECM, and are directly influenced by the feedback from another sensor...... Some of you have just been lucky in finding a solution by merely replacing the "one" sensor that isn't grounded right or that is shorted somewhere in the harness. If I ever discover the specific short or bad ground in the circuits on my 94 GMC 1500, I'll let you know where and what. Till then I'm seriously considering selling this thing for scrap and getting a ford.

2 out of 2 people think this is helpful.

Please do because mine is acting up. My speedo started going haywire but I'm not sure if it's a loose wire because it happens and then it stops. One day it will be fine and one day it won't be. I could hit a pothole and it starts to slip out of gear. I'm going to go to the scrap yard and get a couple used vehicle speed sensors and try it for the helll of it

2 out of 2 people think this is helpful.

And I have a 93 sierra k1500


I got in touch with GMC about getting a tech manual, or whatever else I could use to chase down the problem on my truck......They didn't have anything on before 96, but the lady I was having the chat with sent me a couple email addresses.....One was....... http://www.autobooksbishko.com/search.cgi?year=1993&make=GMC&category=Shop+Manual.....The other was Helms, but I just randomly selected to go with bishko.....Cost $44.67 to get a cd on "my" 94 sierra, plus of course the various options that it could have come with in the same line.....It has cost me around $70.00 in ink to print out all the pages I've wanted to look over better.......Hard to bounce around the PDF file as quick as you can a book, especially when you have to flip back and forth every once in awhile.....The printed manuals themselves cost a bit more than the cd.....But if you wanted "every single of the manual" printed out it would probably cost you about three times what the printed manual itself cost's.......Personally I'm glad I went with the cd.......At least that way if a page gets destroyed by the wind of saturated in oil, I can easily print out a new one.....from either the original disk, the backup I put on my hard drive, or the one I put on a small flash drive......I have about 800 pages out of over 3000 printed and it told me "exactly" where to look and what to test to find at least "one" ground wire disconnected that literally killed my battery while it was running. Oh.....Update.....I decided 'before' receiving the cd to replace the distributor because I discovered an oil slick inside of it, and clear evidence of dried oil like stains on the plate......actually caused by a deformed and cracked distributor gasket.....I just decided that, "If I'm gonna take it out and have to put it back in right, then I'm going with a new one".....At least 90 percent of my problems were cured with the new distributor, but there was/is still a little glitch.....start right up, stubborn about idling till it warmed up good, run like a new one, almost is all new now.....After it gets hot, if you shut it off, it ain't starting back up......Took a 60 mile round trip, left the engine running when I stopped by a couple stores and a friends house for maybe fifteen minutes each with the doors locked.....Set and idled like it was new, ran great though the speedometer didn't work at all, and I later discovered that neither did the rear lights.....The manual literally told me exactly what to do to find the broken ground wire beneath my truck, and where it was located......I was hoping that "that" was the problem....But no........I have come to the conclusion, whether correct or erroneous, that my starter solenoid is half shot, 'but' in order to find out, you have to, on my truck, take the starter off the truck just to get to the blame terminals to do the test's that the manual describes...IF IT WAS A FORD, I could tell you in five minutes if the solenoid was bad......But I will have to say that the GMC has been generally much easier to work on otherwise.....I'll let you know tomorrow evening whether or not it "was" the solenoid that caused the last of the problems. Though I may just decide to go with a new starter....Either way, I'll say something even if it's just "damn!"

1 out of 1 people think this is helpful.

for what it's worth.....Finding the loose ground wire, and reconnecting it where it was supposed to be "at least" fixed the speedometer....I ain't saying that that is "your" problem with the speedo, just that fixing the broken ground fixed my speedometer problem.......

2 out of 2 people think this is helpful.

i had the same problem on my 98 chevy pu with a 4l60-e transmission,gages stopped working speedo reads 0 and abs lite came on .....took it to my transmission shop they looked at it took 10 min to find problem....the wires going to the vss sensor had been chewed up by a Squirrel....spliced wires back together and problem is fixed...all is working fine.

5 out of 5 people think this is helpful.

I got a 1995 chevy k1500 5.7ltr 4L60E tranny and mine did same thing i replaced output on transfercase cleared it right up..

Had all the same problems. Even had tranny rebuilt and still same issue. Replaced everything only to find at the last that the ignition switch inside steering column was the problem. Found it on amazon for $52.00 Works great now!

I have an 05 Tahoe Z71 my problem is the speedo pegs out all the time. Sometimes I show no oil pressure, tach will peg out. Fuel battery and temp are always good.

also sometimes if I go back and forth several time on the ignition but not turn it over it will reset the panel for a while.

I'm haveing the EXACT same problem that Raymond commented up top some. I don't see it being my transmission considering I have every gear. Please any input helping me would be appreciated!! Thanks My 2000 Tahoe LT 4×4 has that not changing gears issue. Put it in drive - nothing, go to 1stthe and it grabs, you manually shift it, works great, even drops down gears and then changes great. The main problem is after I manually shift it, I come to a COMPLETE stop, it goes right into basically neutral, but if I don't COMPLETELY stop it keeps pulling. Once that happens, I have to manually shift it out again. Does anyone have an idea of what the issue may be?


Z71Doug. I am very far from being a mechanic. However, from some of the research I've done because of my own problem with a 94 GMC. It "sounds like" you might have a problem either with trash in your trans fluid blocking or partially blocking one of the fluid chambers. Or with one of the solenoids acting up inside the transmission which will prevent it from changing gears properly. But, like I said, I am far from being an experienced mechanic, and can only hypothesize.


I have a 2001 Yukon 4X4 that wont shift into 3rd or 4th. My speedometer doesn't work, the ABS light is on and showing a P0502 DTC (circuit low). Need some input on this issue.

4 out of 4 people think this is helpful.

For what it might be worth, the first thing I'd try is to look for a short somewhere in the speedometer circuit, the ABS circuit, or the instrument cluster to ground circuit. May possibly even be a fuse, gauges fuse, brake fuse. But like I said above. I ain't a mechanic I "think" that an electrical problem can effect the voltage that should be going to the 3-4 shift solenoid and "maybe" stop it from shifting right. Go to an auto parts store and buy either a Haynes manual, or a Chiltons manual for the Yukon. Might help you some. And hope a "real" mechanic gets up in here and gives you some good advice.

1 out of 1 people think this is helpful.

We just went trough the exact same thing, 99 sierra z71 with np246. U joint took out the adapter housing, changed it, put transfer case in and tranny wont get out of 2nd gear and would only get to 2nd by manually shifting it. We did ohm test on wires from sensors and they all read 4.5 except one, from the speed sensor on right PASSENGER rear tailshaft of transfer case. The wire coming in read 17.5 and had stretched I guess during the removal process...wire fixed and all lights went off and shifts normal again. If your checking your ABS on front sensors, jack the wheel up spin it and it should read .350 coming out of the sensor at plug...just in case you have a bad wheel sensor and we eliminated that. If anyone takes a transfer case out I suggest unplugging all wires to dropping it due to the fact that the wires are too short to let transfer case sit on the ground. Cant tell you how relieved we are and I wanted to update this post to try and help. I also posted a picture of the adapter plate to help anyone contemplating changing out a cracked adapter. I will post our install and uninstall also. Going to share my experience after uninstalling 4 np246 NP8 transfer cases and installing 3 this weekend on sons 1999 sierra 4x4. There are not that many videos out there so some helped but passing this info on, last uninstall and install took 1.5 hours total. IMPORTANT, LOOK AT NUTS AND ENSURE YOU ARE DROPPING JUST THE TRANSFER CASE AND NOT THE ADAPTER HOUSING ALSO. There is no need to loosen adapter housing unless it is cracked as ours was, if adapter is cracked that requires crossmember drop and tranny jack to hold transmission up because adapter housing sits on motor mount and bolts to transmission, change rubber O ring on front of adapter is all...no gasket required. If you need a new adapter apparently GM has an updated strengthened housing There is no need to drop crossmember, case has no mount because it just hangs on back of adapter housing attached to transmission mount. Considering the adapter lasted 17 years with 75 pound transfer case hanging off of it is impressive. I like the design for install lol. Tools needed 11 mm box end for u joint saddles 15 mm small 3" box end, 1/4" ratchet with 15mm socket 18 for drain plug, 19 for sensors Oil transfer hand pump zip tie Uninstall 1. Take off both drive shafts this makes getting to nuts so much easier and you do not fight trying to stab the front shaft while trying to stab 6 studs through adapter, might as well replace u joints if they have movement if none just shoot em with grease. 2. Drain case, drain plug 18mm 3. Loosen 5 of the 6 15mm nuts holding transfer case on studs. The small 1/4 ratchet is a dream for 5 top and side nuts, box end for bottom nut but leave bottom nut tight until wiring is unplugged because trapped oil in adapter will run out. 4. Unplug all 3 sensors and other 2 plugs. 5. Loosen last nut and let oil drain in pan 6. Slide case back, kick tail shaft up, turn case at an angle and it will clear the crossmember. A second person for this is the ticket, if your solo like I was for one of the installs it is tricky but after resting case on chest it worked out. Install 1. Ensure all sensors and new seals are in replacement unit, if used unit...finding correct seal for front shaft is pain so keep your old one so you can check O.D. AND I.D. . Oreillys number, 710495 2. Make sure flange on adapter is clean and all oil is out of inside of adapter 3. Lift case and work it around until the tailshaft and studs are above crossmembers so that you can rest them on both crossmembers. 4. Now put gasket on the studs as your buddy lifts the front of case a little allowing you to do so. 5. Stab case ensuring the gasket is still in place 6. One person can hold tailshaft while other puts 2 nuts on to hold it in place, now relax and reverse steps 1 thru 6 above. Note, our fill plug was stuck so instead of cracking case attempting to break plug loose we just took off sensor on right side of tailshaft and filled through that hole with hand pump. Hope this saves at least one person a headache.

2 out of 2 people think this is helpful.

I have a 2001 Chevy Blazer 2WD 4.3L SFI 6cyl. Just like the original poster, my speedometer is always at zero. Unlike the original poster, I have no issues with gear shifting; it goes from 1 to 4 with no problem. My odometer is also frozen at the same mileage. Any ideas as to where I should look first?


The wire is going to the transfer case there's three plugs all the plugs are the same the plug that goes to the transmission harness make sure your color codes are all the same I just done mine speedometer will not work got them looking the probe was hooked up backwards truck does a good job now transmission works perfect speedometer works perfect

1 out of 1 people think this is helpful.

I have a 2003 Silverado that I just replaced the 5.3 motor on i drove it home from work and it ran great no issues the next day I went to drive it to work and once it warmed up it stopped shifting almost like the tranny went out but I have had no issues with it I had to call a tow truck and when he arrived he drove it up the flat bed with out a problem once I got to work the mechanic there checked it out but we can't figure out what the problem is it drives fine until it warms up any ideas what it could be?

i Have to replace my Shift Solenoid (1-2) any idea if i have to drop the pan 2005 Z71 Sierra 5.3L


Yes you have to drain and drop the pan. Your trans is a 4L60E.

i had the same problem with no speedometer and no 3rd or 4th gear shift. it was a wire connection behind the battery that came undone. i plugged it back in and everything worked. it came unplugged when i took out the battery. thanks

it was a plug that came undone when i took out the battery. thanks.everything works just fine now.

Wires pins on plug to speed sensor were pushed in to far on plug not sticking out far enough to make contact. Pulled back out with needle nose and gently plugged back in. Problem solved

I recently purchased a 02' Chevy Silverado w/4WD. Everything running great until returning from an out of state trip. Within 10 miles from home the speedometer began jumping all over the place, later when slowing down to turn at an intersection the speedometer dropped to zero and would not shift out of 1st. After 1st checking fuses, I replaced both speed sensors located on either side of transfer case. Truck works great now, cost less than $70 for two speed sensors, used a 3/4 box end wrench on one side the other required a 3/4 deep socket.

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