Transmission Not Shifting Properly
 

Hi everyone, long-time lurker, first-time poster. I have a 2001 Blazer 4dr, 4wd with 198K miles on it. I'm having trouble with the transmission, I think. It pulls out normally but sounds like it 'hangs up in neutral' for a moment shifting from first to second when I'm trying to pull out quickly. Runs well, shifts alright from second to third. Around 45mph, as the tachometer is around 1500rpm, it should be trying to shift up into fourth. Instead, it's hopping up into fourth and right back down. The tachometer jumps a few hundred RPM then drops back down, with the vehicle jerking slightly, back and fourth. Letting off the throttle or pushing it down seems to help. Also, on a hill, it doesn't seem to downshift properly. I can't tell what gear it is in, but when I push down on the gas it tachs out and doesn't down shift. Coasting down a hill it seems to hold back, again like it's not in fourth gear.

I don't have a diagnostic computer so I can't tell you if there's any error codes from the transmission.

I've already changed the throttle position sensor, that didn't make a difference?

Can anyone help me with what I should do? I really need to get this fixed.

TIA!

Rebuild the valve body. Orange box kit from Transgo, hardened valve body plate and a corvette servo 2/4 servo.

Do this FIRST, then if it's still jack'd up, have it rebuilt - your rebuilder will re-use your corvette servo and trans-kit.

Details:

4L60E 4L65E Shift kit Transgo Shift Kit 4L60E 4L65E

Transgo Shift Kit Install instructions, In car, by the DIYer - S-10 Forum

4L60E 700R4 4L80E 4R100 E4OD 2004R C6 TH350 TH400 Transmission Parts: Corvette Servo kit for the 700-R4, 4L60E, 4L65E Transmissions

4L60E transmission valve body plate 4L60E transmission

This can all be done with out removing transmission and IS WELL WORTH performing!

... Been there.

Thanks. That's a little confusing though. Do I need all those parts for rebuilding the valve body? I don't mean to sound ignorant, I just know very little about transmissions.

Man, thinking about it, it could be a solenoid too. Are you getting any OBDII codes?

I have no idea, I don't have a code reader or diagnostic computer or anything like that.

I'd take it to an auto parts store that will scan it for free if you don't have a buddy with a scanner.

Probably a slipping 2-4 band with a worn out drum. Buy an ATSG manual or find a tranny shop.

Don't throw $$$ away on shift kit stuff without first fixing the core problem, you'll regret it later.

If 2-4 band fails completely, I believe you'll still have 1st,3rd, (and reverse??), so it won't leave you totally stranded. If it was mine I'd keep driving it until I had time to find a good v6 4l60e tranny from pick-a-part ($125 here). Then you can dismantle/inspect/repair/scrap your old one without any time constraints.