Refurbished internal harness with pressure switch, EPC, TCC, PWM, 3-2 and both shift solenoids for 2003-up GM 4L60E, 4L65E and 4L70E units.
When a 2003-or-later Silverado 1500, Sierra 1500, Tahoe, Yukon, Suburban, Avalanche or Express van starts throwing two or three transmission codes at once - a shift solenoid performance code here, a converter clutch code there - the culprit is usually not one bad part but a heat-tired electrical package inside the pan. This refurbished master kit swaps all of it: shift solenoids A (1-2) and B (2-3), the 3-2 downshift solenoid, the EPC pressure control solenoid, the TCC on/off and TCC PWM solenoids, the pressure switch manifold, and the internal wiring harness with its pass-through connector. The same layout is used in the 4L65E and the 4L70E.
The 4L60E uses only two shift solenoids to pick four gears. The computer switches A and B on and off in a fixed pattern, and that pattern moves the 1-2 and 2-3 shift valves; ATRA's solenoid chart lists 1st as both on, 2nd as A off and B on, 3rd as both off and 4th as A on and B off. The EPC solenoid is a variable-force unit that sets line pressure, so it decides how firm every shift feels. The TCC on/off solenoid enables lockup and the PWM solenoid controls how quickly the converter clutch applies. All of them are fed from the actuator feed limit circuit, which Sonnax puts at roughly 115 psi in this unit, and all of them hang on the harness this kit replaces. The pressure switch manifold on that harness reports manual valve position so the computer knows which range you selected.
Pull the codes and read them as a group. When several solenoid circuits set together, ATRA traced one known cause to a bad crimp on the shared 12-volt feed circuit, so inspect the case connector and its terminals before condemning anything. With the connector unplugged, ATRA Bulletin 269 gives the shift solenoids at 20-40 ohms and the pressure control solenoid at 3.5-8.0 ohms across the case pins. Our 4L60E shift solenoid symptoms and testing guide walks through the pin map and a commanded-gear test. If every circuit reads correctly and the shift problem stays, the valve body bores may be worn, and a new solenoid set will not fix that; see 4L60E common problems and fixes for the next step.
This kit is listed for GM 4L60E transmissions from 2003 on and carries the 2003-style harness and pass-through connector. That covers 2003-2005 cleanly. GM changed the internal harness and pass-through connector again during 2006 when it added an input speed sensor, so a 2006-2008 owner should compare the connector on this harness to the one in the pan. Starting in 2009 GM dropped the 3-2 solenoid and the pressure switch manifold in favor of an internal mode switch, so a 2009-up transmission does not use this assembly. If you are unsure, send us your year and VIN and we will check it, or browse every 4L60E part we carry. Owners of 1996-2002 trucks need the earlier-style 1996-2002 refurbished master solenoid kit instead.
Refurbished means the solenoids and harness are reconditioned units rather than new, which keeps a complete electrical refresh well under the cost of buying every piece separately.
| Condition | Refurbished |
| Includes | Internal harness, manifold pressure switch, A and B shift solenoids, 3-2 downshift solenoid, EPC solenoid, TCC solenoid, PWM solenoid |
| Fits | GM 4L60E 2003-on; 4L65E, 4L70E |
| Weight | 1.99 lb |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is listed for 2003-up, but GM changed the internal harness and pass-through connector in 2006 when the input speed sensor was added. Compare the connector in your pan to the one in the photos, or send us your year and VIN and we will confirm.
No. From 2009 GM eliminated the 3-2 solenoid and the pressure switch manifold and moved to an internal mode switch, so this assembly does not apply to those transmissions.
Inside the pan the harness lives in hot fluid for years and the insulation gets brittle and cracks. A cracked wire or a leaking pressure switch manifold causes intermittent codes that a single solenoid swap will not cure, so the whole assembly is the one-trip fix.
Dexron VI ATF. Check the level hot with the engine running in Park, then road test and recheck.
Yes. Clear codes and reset the transmission adaptive pressure values with a scan tool. Until the computer relearns, shifts can feel firm or uneven.
Only if the TCC solenoid or its wiring is the cause. On these units P0741 is often valve body bore wear, so check the solenoid circuits first and vacuum test the valve body if they pass.
