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no shift to 4th gear


tgbZ34

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Hi All,

After 160,000 trouble-free miles the old '94 Z34 tranny has finally shown its age, so I can't complain about that. The tranny won't shift into 4th either automatically or manually, whether it is hot or cold or lukewarm. The handful of threads with similar problems talk about unplugging the TCC, fluid flushes, etc., but since it doesn't even get to 4th the TCC won't have a chance to engage. I dropped the tranny oil pan over the weekend and it had the usual fine metal powder coating the pan magnet and the fluid was still red, so I don't think a flush would do much good (harm?). The shop manual says it could be either control valve assembly (or shift solenoids, inside tranny side cover) or 4th gear clutch / shaft. There wasn't much metal in the pan so I'm leaning toward the control valve. Has anyone had a similar problem and has changing the control assembly fixed it? How much of a pain is it to get the side cover of the tranny off while the tranny is still in the car? I'd hate to throw a rebuilt tranny in it and find out it could have been fixed for cheap, especially since my cash-poor daughter is driving the car. It sucks the gas big time while stuck in 3rd!

Thanks

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a subframe drop would be required to remove the side pan. the good news is that you only need to loosen the right hand bolts and remove the left bolts and lower the subframe as if it were hinged. make sure to properly support it and everything, of course.

 

I'm not sure on you problems cause, btu i wish you luck... I would think the problme would be relatively simple and not require a tranny replacement or rebuild.

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I am also having the same problem on my 95 cutlass w/3.1 M code. I just recently replaced the cam sensor and did some repairs to the injector wiring harness, as they rubbed through on the intake manifold and shorted out.

 

Anyway, I wondered if I perhaps just overlooked something when re-assembling, because now the car won't shift to O/D.

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You should be able to have a shop take it for a drive with a scanner hooked up and have it checked. If the clutches were worn, it should attempt to shift, but would either seem like the car was in neutral, or it feel like its slipping. the shop would be able to tell if the computer is commanding the shift into 4th gear. If it is, than it would most likely be a shift solenoid. If it is not commanding the shift, then it would be more than likely a computer issue.

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  • 1 month later...

Problem was found! There was no "shift solenoid A" voltage from the PCM, pin A22 if I remember right. One of the quad driver outputs was blown. I verified the shift solenoids would at least draw current by momentarily connecting each one to 12V and watching the current on a DVM. I could also hear them click inside the transmission. I found a $30 ECM on ebay and after I put the original chip in the replacement computer (it wouldn't run with the '95 Monte Carlo chip) the old Z runs great once again.

 

Thanks for the repair suggestions!

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