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GMTechBernard, Shop Foreman - GM World Class Tech
Category: Chevy
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Experience:  GM
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OBD-II code reader showing P0785 - shift timing solenoid malfunction

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OBD-II code reader showing P0785 - shift timing solenoid malfunction
Hello! What prompted you to replace the 1-2 shift solenoid? And the P0785 didn't show up until AFTER the 1-2 was replaced???
Customer: replied 7 years ago.
I was getting P0781, which was the 1-2 shift solenoid malfunctioning, also I have a B&M Stage II shift kit in the 4L60E as well, if it helps any.

The reason why I ask, is because anytime there are MULTIPLE transmission solenoid codes, its usually the result of a failed ignition switch. However, since only two codes appeared and were one at a time, I think at this point, its unlikely the result of an ignition switch failure.


P0785 is for the 3-2 downshift solenoid. Either the solenoid is faulty, or something got damaged while the 1-2 solenoid was being replaced. (connector knocked loose, wire rubbing on pan or valvebody, etc...).


The 3-2 solenoid is #394 in the picture below, which is at the opposite end of the 1-2 solenoid.



Customer: replied 7 years ago.
I didn't even go close to 394 the one I replaced was 367A on the oppisite end, I don't even think I touched it when I replaced the filter.

I read a bunch of other thread on that ignition switch too, is a key ignition switch or is this "ignition switch" in the transmission?

Its the key ignition switch, but you don't have enough codes to support replacement of that.



Customer: replied 7 years ago.
So you think if I replace 394 I should be good to go? P0783 is the 3-4 shift malfunction code. I don't see a 3-2 downshift code in this book, is that what the P0785 is the 3-2 downshift malfunction?
Yes, P0785 is for the 3-2 solenoid and that is 394 in the picture. Is it likely to fix it? yes, but of course I cannot guarantee that it will, sitting behind my computer and never seeing the vehicle!
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Customer: replied 7 years ago.
Kool, I'll give it a shot. Thanks.