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Premium Member
2007 TBSS AWD
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31,503 Posts
Discussion Starter #1 (Edited)
Common failures on 4L60/65/70E, symptom -> cause -> any possible repair:

1. Slow, slipping or no reverse: “lo-reverse” clutches are worn out, fluid leak in the reverse apply circuit, or broken sunshell. It is possible to remedy a fluid problem by removing the checkball from its cage in the case in the rear of the trans may help (must remove valvebody), or adding a high-viscosity additive such as Lucas Transmission additive or other seal restorer product. May also have worn boost valve (can replace in the pan).

2. 1-2 shift does not happen at WOT until you let off the gas: Best case: try replacing the TPS. Middle case: leak in the 2nd gear apply circuit (servo assembly or 1-2 accumulator). Doublecheck by using the pressure gauge and watch for a big drop when the PCM commands 2nd gear. Worst case: poor line pressure rise (see below).

3. 1-2 Shift shudder at WOT; delayed or abnormal 1-2 shift; There's a problem ONLY on the 1-2 shift: 1-2 accumulator piston cracked or stuck cocked in the bore. Check the yellow spring inside the accum housing for breakage. Also, if the accumulator housing walls are scored, the housing must be replaced. Easy fix in the pan.

4. 1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.

5. Trans does not upshift out of first, speedometer reads zero at all times: VSS failure. Easy fix on rear of transmission, but xmember must come out to access VSS.

6. No 3rd or 4th gear: “3-4” clutches are worn out. R&R. The car is safe to drive (in 2) until you can get it fixed.

7. Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in reverse may be abnormal; sunshell is fractured. R&R. Try not to run or drive the car or further damage could result.

8. 1st and 3rd only, no 2,4 or R; sunshell is fractured or splines are sheared off. R&R. Try not to run or drive the car or further damage could result.

9. No 2nd or 4th gear. 2-4 band is slipping. Servo seals may be damaged (can be fixed without removing trans. Otherwise, 2-4 band is worn out. R&R.

10. Trans shifts into gear harshly, 3rd gear starts, manual 2nd available but no 1st, no 4th, and no TCC lockup: No power to transmission, or trans is in limp-home mode. Check trans fuse underhood, and make sure transmission electrical connector is plugged in. Easy fix.

11. No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

12. No 2nd or 3rd available: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

13. No TCC lockup: Brake pedal switches improperly adjusted (always on), TCC solenoid failed (easy fix in the pan), TCC clutch worn out (must remove trans and replace TC).

14. TCC always locked: TCC apply solenoid circuit shorted to ground, TCC solenoid blockage (easy fix in pan), or TC broken (must remove trans and replace TC).

15. Horrible noise in 4th and feels like the brakes are on: overrun clutches are applying due to a cracked or leaking forward piston. Overrun clutches will be worn out after 30 seconds of this behavior. Car can be safely driven in D. R&R.

16. Soft shifting, gradual performance degradation: Poor line pressure rise due to leaking boost valve, clogged EPC filter screen, failing EPC solenoid, or worst case: leaky seals throughout. Transgo HD2-C kit fixes first two without removing trans. Seal restorer may fix last problem, but probably R&R. Also try a transmission flush with BG brand products (Firestone stocks it).

17. No forward movement in OD or D, but L2, L1 and R work: Forward sprag is broken. R&R. Try not to run or drive the car or further damage could result.

18. Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts will eventually break.

19. Loud bang, grinding sound, loss of all gears, and a binding driveshaft: snapped output shaft. Try to wiggle driveshaft - if more than 0.020" play, that's the sign. R&R.

20. Trans seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the trans goes into 3rd gear: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either. R&R sooner rather than later.

21. No movement in any gear: pump failure, or total loss of fluid. R&R, or refill pan and find the leak. If out of fluid, avoid running the engine until the trans is refilled to avoid pump damage. To check for pump failure, check fluid level with the engine off, then start the engine and recheck fluid level. If level does not go down when engine is running, the pump is broken.

22. Transmission does not shift automatically, only manually. Swap in a known-good PCM, check wiring, check other sensors such as VSS and TPS.

23. 3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows about it.

24. Car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: Transmision is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the underhood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode.

25. Fluid leak out of the front of trans where the converter connects; partial or full loss of movement: Front pump bushing walked out. R&R. May have to replace converter also if hub is scored. Note that a leaking front seal usually means the bushing is walking out (i.e. call your local trans shop and schedule an appt.).

26. Torque converter shudder in 4th while lockup is engaged; problem goes away when the brake pedal is pressed slightly to unlock converter. Have a shop verify line pressure, and provided no valves in the TCC hydraulic circuit are worn, replace the torque converter. Also, Lubegard Shudder Fix will at least fix this for awhile. Or try a transmission flush by a shop that uses BG brand products.

27. Shift suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all, replace TPS.

28. All fluid pumped out through the vent tube: Plugged cooler line. Flush the transmission cooler and cooler lines. Also could be overfiled transmission.

29. Car acts like it's in OD in neutral, car is locked stationary in R, engine feels loaded in P, all four forward positions work fine:Internal crossleak feeding the forward clutches all the time. Most likely a cracked input housing. R&R required. Car can safely be driven gently in forward gears until the repair.

30. Needle bearings in the pan, first gear and/or reverse may be noisy: Either a torrington bearing or a planetary bearing is on its way out. Trans will eventually die a loud, catastrophic death. Cheaper to rebuild now (saves further damage to hard parts), but requires R&R. It is drivable until it breaks.

31. 1-2 or 2-3 shift is slow/soft above part throttle: Trans is on its way out. R&R.
 

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The Lurker
TrailblazerSS 06
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13,844 Posts
31 common problems? Wow! these tranny's suck!
 

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Whiskey Tango...
AWD TBSS
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4,084 Posts
Those are just the common problems there are more! Hopefully I'll never have to refer back to this thread to figure out WTF just happened.
 

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Premium Member
2007 AWD
Joined
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4,748 Posts
My issue isn't on there:

Issue:No 1 or 2 via manual shifting, or putting it in D. R still there, for one or two tries. In D, slow forward acceleration until normal 3rd gear speeds, then 3rd and 4th and TCC lock work fine.

Fix:R&R-new clutch springs and sunshell.

^
On a built trans at that.


***And I fail to see how a shitty transmission that NEVER should have been put into the trucks in the first place = "driver failure".
 

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Premium Member
'08 TrailblazerSS
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4,146 Posts
***And I fail to see how a shitty transmission that NEVER should have been put into the trucks in the first place = "driver failure".
Tens of thousands of bone stock TBSSs live long and happy lives without one trans issue or hiccup. If it was a shitty transmission they would all be broken. Whats the difference in the ones that break to the ones that don't? In vast majority of the cases, it's added engine power, and how they are driven / maintained.

Yup there are tranny failures in non modded bone stock TBSSs, but not nearly as many as you think. It's probaby the same failure rate for any other vehicle including a front wheel drive vehicle.
 

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Banned
TBSS
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11,699 Posts
Tens of thousands of bone stock TBSSs live long and happy lives without one trans issue or hiccup. If it was a shitty transmission they would all be broken. Whats the difference in the ones that break to the ones that don't? In vast majority of the cases, it's added engine power, and how they are driven / maintained.

Yup there are tranny failures in non modded bone stock TBSSs, but not nearly as many as you think. It's probaby the same failure rate for any other vehicle including a front wheel drive vehicle.
Bingo!

80k on my stock well beaten on trans, it doesn't miss a beat. Doing burn outs and launching from every stop sign will kill any trans.

It's all about how you take care of things.
 

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Premium Member
2007 AWD
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4,748 Posts
Well, the whole time I had the SS I lived in Iowa where "hot" is 80 degrees.

I always kept good fluid in it, too. I swapped out the perfectly working stocker for a supposedly bulletproof* one with something like 15k on it. I beat the shit out of it for about 5 months or so, at the track and on the street. After my motor gave up the goat, I never really got into the whole track thing again. Only ran it MAYBE 10 times total after that. Still with good fluid and all. Was going to have it refreshed and go to a stage 7, but then in simple driving the "built" trans went kablooey. Not dogging it, just cruising on the highway.

They shouldn't have put that trans in this vehicle. It's great for the lighter cars it was in. The TBSS's are just too damned heavy and are supposed to be purpose built to go fast.


*I know nothing's "bulletproof".
 

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Premium Member
'08 TrailblazerSS
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4,146 Posts
If the TBSS was designed and built to be bulletproof 95% of the people on this board wouldn't be able to afford one. GM builds street transportation, not race cars. There is always a trade off and sacrifices to be made. Purpose built race transmissions do not have longevity for high miles and are very expensive. Medium strength transmissions are heavy and hurt fuel economy more often than not. The expense and cost to design a new unit is astronomical which is why they span it across several platforms. You have to worry about warranty costs down the road with the 100k warranty. You have to worry about towing capacity. It has to work in subfreezing temperatures and in death valley and deliver a smooth comfortable shift. There are a lot of things to juggle when bringing a vehicle to the market.

IMHO we were lucky to get the TBSS at all, it seems to me that they built it as an afterthought knowing the future of the S/T line was in jeopardy and was getting to the end of the production run.
 

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Premium Member
2007 AWD
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4,748 Posts
It has to work in subfreezing temperatures and in death valley and deliver a smooth comfortable shift.
They should have just concentrated on the underlined, that would have been awesome.

 

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Premium Member
'08 TrailblazerSS
Joined
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4,146 Posts
They should have just concentrated on the underlined, that would have been awesome.

Well, mine works great :D

Almost 30k with a 4200 stall, and cooler and about 100 or so passes down the track and a shitty ass stop and go 30 mile commute everday.
 

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Premium Member
2007 TBSS AWD
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31,503 Posts
Discussion Starter #18
Well, mine works great :D

Almost 30k with a 4200 stall, and cooler and about 100 or so passes down the track and a shitty ass stop and go 30 mile commute everday.
Driver has everything to do with it. I could make a 500 rwhp engine live behind a stock 4L60E by babying it or I could kill a 4L80E behind a 400 hp motor by abusing the shit out of it. Thing is that most people want to drive hard after spending money on mods and you need to be prepared for that to be costly.
 

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The Lurker
TrailblazerSS 06
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13,844 Posts
Well, mine works great :D

Almost 30k with a 4200 stall, and cooler and about 100 or so passes down the track and a shitty ass stop and go 30 mile commute everday.
4200 stall? How's that working?
 

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Premium Member
'08 TrailblazerSS
Joined
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4,146 Posts
4200 stall? How's that working?
Way too much stall for a basically stock motor (stock cam). It was supposed to be a 3400 but thats a long story there. I'm just too lazy to pull it out and can't afford to lose the truck for the down time while it gets restalled. It's actually damn tolerable to DD a stall this high on a stock motor. I think a part of me was going to do a head / cam / intake combo to take advantage of the stall but then my economic reality set in :doh: .

But hey, it sure is peppy :biggrin2:
 
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