Seven-piece solenoid set with harness for 2003-2007 GM 4L60E units: shift A and B, 3-2 downshift, EPC pressure control and TCC/PWM.
Late-model 4L60E owners with a 2003-2007 Chevrolet, GMC, Buick, Pontiac, Hummer or Oldsmobile truck or SUV usually end up here for one of a few reasons: a P0785 or P0758 code, a truck that suddenly holds second or third and will not shift, a hard bang into each gear, or a converter that will not lock at cruise. This seven-piece set replaces shift solenoids A and B, the 3-2 downshift solenoid, the EPC solenoid and the TCC/PWM lockup solenoid, along with the internal harness and mounting hardware.
Think of the solenoids as the hands the transmission computer uses to move hydraulic valves. Shift A and B decide which gear you are in, the EPC solenoid decides how hard each clutch and band applies, the TCC/PWM solenoid controls how the converter clutch locks, and the 3-2 solenoid manages the overlap between the 3-4 clutch letting go and the 2-4 band grabbing on a downshift. When a solenoid gets slow rather than dead, the result is harder to diagnose. Transmission Digest described a 4L60E-equipped S-10 that set P0758 with a solenoid that still measured inside the 19-31 ohm spec, because it was responding too slowly to its command. Resistance alone did not catch it; the wrong gear ratios on the scan data did.
Read codes and look at commanded gear against actual gear ratio while driving. If the computer commands a gear and the ratio does not follow, you have a solenoid response or hydraulic problem. ATRA found that the most likely cause of limp mode with 3-2 and other solenoid codes on these units is a wiring or connector fault, so test the harness and case connector before you condemn anything. Also know that a broken 3-2 control valve spring in the valve body, which Sonnax says is common in late 4L60E units, can cause a 3-2 bind and overheat the 2-4 band even with a good solenoid. Our 3-2 downshift solenoid and P0785 guide covers that diagnosis in detail, and the EPC solenoid guide explains harsh-shift complaints.
This set is for the late 4L60E in 2003-2007 GM applications. Units from 1997 through the 2003 changeover use an earlier-style harness and connector, so 2003 owners in particular should compare the old harness and case connector against the new one before installing. Listed replacement numbers include 8677314, 8684216, 24212690, 24227792, 8683187, 74420K-1, K77995, 12121299, 24215111 and 24219581. Send us your year and VIN if you want us to confirm, and browse our 4L60E parts collection for related hard parts.
Drain and drop the pan, pull the filter, unclip the case connector from inside the case and lower the valve body enough to reach the solenoid bores. Each solenoid is held by a clip or bolt. Keep the valve body bolts sorted, because a long bolt in the wrong hole will bottom out and can crack the case or leave the body loose. Install the new harness instead of reusing the old one; cracked insulation can make a brand new solenoid read as faulty. Torque the valve body bolts in sequence, install a new filter and pan gasket, refill with Dexron VI and clear codes before the road test. If lockup problems remain after the electrical work, the 2003-2007 4L60E TCC solenoid listing and a Sonnax-updated valve body cover the next steps.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
2003 was a changeover year for 4L60E harness and connector styles. This kit is for the late-style 2003-2007 units, so compare your old harness and case connector with the new one, or send us your VIN to confirm.
No. It includes five solenoids, the internal harness and mounting hardware. Buy a filter and pan gasket separately since the pan must come off.
Yes. A solenoid can measure within spec but respond too slowly, which shows up as wrong gear ratios on a scan tool. That is one reason replacing the full set on a high-mileage unit is common.
If the 3-2 solenoid or its wiring is the cause, yes. Check the harness and connector first, and be aware that a broken 3-2 control valve spring in the valve body can cause 3-2 complaints that solenoids will not fix.
Many GM rear-wheel-drive and four-wheel-drive trucks and SUVs from Chevrolet, GMC, Buick, Pontiac, Hummer and Oldsmobile. Fitment is by transmission, so confirm you have a 4L60E and not a 4L80E or 6-speed.
Dexron VI ATF, checked hot with the engine running in Park.
