95 beretta z26 down shifting problem. Need help.

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pete812
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95 beretta z26 down shifting problem. Need help.

Postby pete812 » Sun Oct 25, 2015 11:43 pm

Hi My name is pete and I have had a couple of beretta's and right now I have a 95 z26. With 127000.miles. Recently I was driving and the car just started bucking and the cruise control did not work. Once I got off the hwy I noticed the trans kickdown cable came off. So I resecured it and started driving again. When I was driving in traffic I noticed that the transmission was not down shifting as I was slowing down and went I went to accelerate the car was responding like I was still in 4th gear. What can I do to resolve this problem before it ruins the transmission?
I would really appreciate any ideas on what to check or if there is a link that can maybe help me with this problem.



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Re: 95 beretta z26 down shifting problem. Need help.

Postby SuperLbody » Mon Oct 26, 2015 12:34 am

I don't believe you have a kickdown cable. What you reattached was the cruise control cable. Kickdown is controlled by a modulator which is controlled through vacuum. Check that the vacuum line is attached as well as the supply line from the intake manifold to the modulator. If that looks good the check valve or reservoir might be messed up.



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Re: 95 beretta z26 down shifting problem. Need help.

Postby pete812 » Mon Oct 26, 2015 2:53 am

Thanks for the reply. I will check that and also were is the check valve and reservoir located?



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Re: 95 beretta z26 down shifting problem. Need help.

Postby Asylum » Mon Oct 26, 2015 5:27 am

The vacuum line for the trans runs under the battery tray and that is an area that is prone to rust and corrosion.
It is also an area that is a known problem for these cars.
It was the problem on my '95 California Z26.


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Re: 95 beretta z26 down shifting problem. Need help.

Postby 3X00-Modified » Mon Oct 26, 2015 8:19 am

I will clarify that there is nothing external that controls shifting. The vacuum modulator on the front of the transmission is for shift quality or firmness only. It adjusts the line pressure to relate to how much vac signal there is... Low VAC means heavy load so higher pressure.

All 4t60-e shift logic is electronically controlled by the ECU. If its not kicking down then the trans is either in limp mode due to some other major issue, or there is some irreversible damage already in the transmission that has gummed up or suck valves in the valve body and only a full rebuild will fix that issue.

Shifting issues on a 4t60-e are rarely fixable by fluid changes, cleaning or re-attaching vac lines. Seeing how it's all electronic and no external mechanical parts controlling it. You have 3 solenoids inside and a bunch of valves that can only be serviced with the side cover off.



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Re: 95 beretta z26 down shifting problem. Need help.

Postby pete812 » Mon Oct 26, 2015 11:02 am

Is servicing the valve body something I can do or has to be done at a transmission place?



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Re: 95 beretta z26 down shifting problem. Need help.

Postby 3X00-Modified » Mon Oct 26, 2015 11:55 am

Depends on how capable you are... I would not suggest the regular DIY guy to tear into an automatic trans valve body... they can be a bit overwhelming.

This is what's in it...

Image

And the rest of the innards...

Image



pete812
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Re: 95 beretta z26 down shifting problem. Need help.

Postby pete812 » Wed Oct 28, 2015 11:53 am

Ok I did a filter and fluid change and it seems to be better then before but I still have to step on the pedal more just for it to down shift. Could the TPS be the problem or if the shift solenoids are going bad would the check engine light come on ?



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Re: 95 beretta z26 down shifting problem. Need help.

Postby ifixalot » Wed Oct 28, 2015 3:14 pm

I believe somebody here recently mentioned on this forum that his transmission was staying in 3rd or 4th gear and he unplugged and reconnected the connector to the transmission and it solved his problem.
This trans is electrically controlled by the ecm which does use the TPS to determine shift points.
You can get cheap TPS on Ebay but I doubt it will solve the problem but you can try it.
You can also check the fuses. I think if the fuse for the trans is blown it will default the trans in 3rd gear.



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Re: 95 beretta z26 down shifting problem. Need help.

Postby pete812 » Wed Oct 28, 2015 5:50 pm

Ok well I will try to unplug the connector and see what happens. If it doesn't work I'm going to have to see what it will cats to have it repaired. I really appreciate everyone's help and information.




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