4L60E Trans '94 Z71 4wd


Old 02-15-10, 02:54 PM
Thread Starter
Join Date: Apr 2006
Location: Texas
Posts: 34
4L60E Trans '94 Z71 4wd

Hello, Have a 4L60E Auto- Trans in '94 Z71 4wd pu, not always going into overdrive when up to temperature. Have changed fluid and filter w/out success. I would appreciate your thoughts as to what to check next.

Best Regards
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Old 02-15-10, 08:12 PM
Join Date: Oct 2008
Posts: 1,312
These transmissions have electrical sensors and actuators which *could* be the problem.

Or it might be a mechanical problem?

You can get a factory service manual set for this (order from dealer or helminc.com) and that would have complete troubleshooting instructions for the electrical. And you would test with a multimeter. And the factory service manual sets cost about $150.00

If it were my vehicle, I would test the electrical components first before taking it to a transmission shop.

Also I suppose before you do anything, check all the wiring and connectors going to the transmission. Lots of dirt and crud down there, rocks can fly up and damage wiring, etc. Be sure the wiring is not damaged and the electrical connectors have clean connections.
Old 02-15-10, 08:21 PM
Join Date: Jul 2009
Location: Washington State
Posts: 312
Hate to tell ya but the OD drum/clutch in those was VERY prone to melt downs seen more than one.When you did the fluid/filter change did you notice a slight "metal flake paint job" look in the pan? It really has a pretty cool look to it and doesn't look like it would be an issue but the opposite is true.It's part of the OD drum flaking off.It is usually defined early on by a "flare" when going into OD (slight slip in feel)
Good Luck
Old 02-16-10, 05:50 AM
Join Date: Jun 2009
Location: California
Posts: 214
How many miles are on this thing, is it has it been worked on before to your knowledge and of course has it had rough service.
Old 02-16-10, 07:40 AM
Thread Starter
Join Date: Apr 2006
Location: Texas
Posts: 34
Thanks on 4L60E

Thank you everyone I'll check those suggestions out an report what I find.

Best Regards,
Old 02-16-10, 11:46 AM
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You can also pull codes to see if there's any tranny codes, they'll be in the 70's-80's range. Here's how to pull GM OBD-I codes:

Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical

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