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Thread: 99 Sierra 1500 shifting problem
01-09-2009, 03:28 PM #1
99 Sierra 1500 shifting problem
I'm new to the forum but have been a long time GMC truck owner.
My 1999 Sierra 1500 4 X 4 SLT Z71 with 135,000 miles on it doesn't want to shift gears when the temerature drops below freezing.
It will stay in 2nd for about a mile then shift t 3rd. After another couple of miles it will then shift to 4th and, again, after another mile or so shift into overdrive. After this it will then shift fine.
I've recently had the ATF drained and refilled with Dexron 3.
I'm hoping somebody can help me fix this minor issue as, apart from this problem, the [COLOR=blue! important][COLOR=blue! important]truck[/COLOR][/COLOR] looks and run great.
01-09-2009, 05:41 PM #2
Welcome to the site!
Hopeully the "tranny" guys will chime in on this.Ryan
2002 Jeep Wrangler Sport 4x4 (the Yellow Jacket)
4inch suspension 3inch body
Straight 6 (383 Stroker within a year)
36inch SuperSwamper TSL.
Daily Driver Weekend Wheeler
2004 Sierra crew cab, 2wd, 5.3 V8
2inch Daystar Leveling kit
single dumped Flowmaster 40 sieries exaust(removed)
Mb Blitz Chrome wheels
Leer Bed Cover(for sale)
01-09-2009, 06:25 PM #3
Can you try putting the truck through the gears manually i.e. 1 , 2, 3, Drive with OD off? Or what ever you cn. But that is one weird problem, I've never heard of it.Trevor - Huntington Beach, CA
2007 GMC 2500 4X4
01-12-2009, 12:33 PM #4
- Join Date
- Jan 2009
try a tps sensor
01-12-2009, 01:16 PM #5
Hi and thanks for the suggestion. What is a "TPS" sensor?
01-12-2009, 02:15 PM #6
Thanks for the suggestion. I have done that and it shifts into first no problem and second no problem but when you selct 3 or 4, if the temerature is below freezing, it will hang up in second gear. After a couple of miles it will then go into third gear and, agter another couple of miles, it will go into fourth.
When the temerature is ABOVE freezing it shifts through all gears real smooth with no problems at all. Weird huh?
01-12-2009, 02:19 PM #7
TPS, throttle position sensor.Don't replace it thats not the problem, I think he meant to say speed sensor. Could possibly be the speed sensor but this on is difficult to diagnose.
01-12-2009, 03:38 PM #8
Thanks RETIRED. I'll check with the local GMC dealer (if he's still in business!!!) for a spped sensor but I still can't figure out why it would be temerature sensitive. Still, it's worth a shot.
Any more ideas?
01-12-2009, 04:30 PM #9
Because the transmission is fully electronically controlled, my first question on these problems is, is the problem with the computer telling the transmission when to shift, or is the transmission not responding correctly when commanded to shift. You might pull codes from the PCM to see if there are any trouble codes that give any direction. From there, you would need one of the more expensive scanners (that can access transmission information) and watch to see if/when the PCM is commanding shifts and if the transmission is responding correctly.'98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
'92 Ford Explorer XLT 4x4 4.0 L A4LD BW13-54 Trac-loc rear
"My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays." Danny in Roald Dahl's Danny The Champion of the World
01-12-2009, 05:21 PM #10
Cold temps will effect sensors especially if they have water or oil getting into them, see if you have any oil coming out of the speed sensor plug.
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