Second Gear Start 4l60e
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Second Gear Start 4l60e Hello! I am quite new here and I’ve browsed this forum a decent amount when rebuilding my 4l60e’s. I’ve rebuilt two so far, and the most recent one has been giving me strange problems.
The 4l60e is out of a 2002 Silverado. It only has reverse, second, third, and overdrive. It throws solenoid A performance code. Dropping it in manual first will also be a second gear start. It upshifts no problem. I do not have a tech-2 scanner, but I’ve probed the shift solenoids with the pan off and power does go to it. It also audibly clicks when it’s powered through the transmission wire harness (both the harness and solenoids are new). I pressure tested the transmission and it was within factory specs. The valve for 1-2 also moves freely in the bore.
I am still quiet a novice at this, yet I am starting to wonder if it is a problem with the afl valve in the valve body, or if the valve body is worn out and is not sealing properly. One thing I did not do when it was torn down was vacuum testing the valve body. I appreciate the help in advance!
The 4l60e is out of a 2002 Silverado. It only has reverse, second, third, and overdrive. It throws solenoid A performance code. Dropping it in manual first will also be a second gear start. It upshifts no problem. I do not have a tech-2 scanner, but I’ve probed the shift solenoids with the pan off and power does go to it. It also audibly clicks when it’s powered through the transmission wire harness (both the harness and solenoids are new). I pressure tested the transmission and it was within factory specs. The valve for 1-2 also moves freely in the bore.
I am still quiet a novice at this, yet I am starting to wonder if it is a problem with the afl valve in the valve body, or if the valve body is worn out and is not sealing properly. One thing I did not do when it was torn down was vacuum testing the valve body. I appreciate the help in advance!
TECH Enthusiast
Joined: Jan 2019
Posts: 677
Likes: 490
From: Roxana, IL
1st) the 1-2 shift valve is the spring loaded valve. It takes 55 PSI to move the 1-2 shift valve to the 1st gear position. Leaving the pump thimble screen out only leaves about 50 psi in the D or M3 position. M1 has 180 plus psi so it should take off in 1st when in M1. The 2-3 shift valve is the one without any spring, it uses solenoid feed (2-3 signal) pressure through a .035 orifice to move the valve in one direction and AFL to move the valve to other position once the solenoid is de-energized and bleeds off 2-3 signal oil.
2nd) a stuck 1-2 shift valve in the released position would result in a 2nd gear start.
3rd) The low roller must hold when in D, M3 so if it doesn't hold you will have 2nd gear. M2 is a snow gear and should have 2nd gear starts. M1 uses the L/R clutch to hold the same planet set from turning as the low roller does. In M1 they use the L/R for added holding capacity when towing or hot-rodding.
I use a Sonnax test plate and shop air to test movement of the 1-2 shift valve. I clamp it to the vb with a vise grip clamp pliers, some times you get away with just holding it tightly. You can also use this plate to test some of the other valves. I bought the 4L60E full sized plate kit and used it twice and went back to the small plate. I didn't like it so I sold it to a friend. I uploaded both instructions sheets for part #'s and where to air test/vac test.
2nd) a stuck 1-2 shift valve in the released position would result in a 2nd gear start.
3rd) The low roller must hold when in D, M3 so if it doesn't hold you will have 2nd gear. M2 is a snow gear and should have 2nd gear starts. M1 uses the L/R clutch to hold the same planet set from turning as the low roller does. In M1 they use the L/R for added holding capacity when towing or hot-rodding.
I use a Sonnax test plate and shop air to test movement of the 1-2 shift valve. I clamp it to the vb with a vise grip clamp pliers, some times you get away with just holding it tightly. You can also use this plate to test some of the other valves. I bought the 4L60E full sized plate kit and used it twice and went back to the small plate. I didn't like it so I sold it to a friend. I uploaded both instructions sheets for part #'s and where to air test/vac test.
TECH Junkie
Joined: Dec 2012
Posts: 3,614
Likes: 1,326
From: Iowa
With a stock valve body, even in M1, the 1-2 shift valve is moved by solenoid oil (AFL oil via a feed orifice to the solenoid)
The manual valve position will not stroke the valve regardless if it has 50 or 180 or 280 psi
The only way you get m1 oil to stroke the shift valve is with an aftermarket valve setup like what is included in the Transgo HD2 kit with "gear command" feature
That said, OP, your most likely issue is a worn AFL bore resulting in low AFL pressure.
Low AFL means there isn't enough oil pressure in that circuit to stroke the spring loaded 1-2 shift valve.
Vacuum test the AFL lineup, replace with a drop in valve from Central Valve Bodies, or use on of either the Sonnax/Transgo kits to ream and repair the AFL bore
The manual valve position will not stroke the valve regardless if it has 50 or 180 or 280 psi
The only way you get m1 oil to stroke the shift valve is with an aftermarket valve setup like what is included in the Transgo HD2 kit with "gear command" feature
That said, OP, your most likely issue is a worn AFL bore resulting in low AFL pressure.
Low AFL means there isn't enough oil pressure in that circuit to stroke the spring loaded 1-2 shift valve.
Vacuum test the AFL lineup, replace with a drop in valve from Central Valve Bodies, or use on of either the Sonnax/Transgo kits to ream and repair the AFL bore
