4L70E Shift Kit 1993-2010, new and ready to install. Fits the 4L70E. Ships fast from the USA.
If a GM truck or SUV with a 4L70E, 4L65E or 4L60E has the check engine light on for P1870, a hard 1-2 shift and a converter that will not lock or will not hold fourth, this is the kit built around that exact chain of failures. It is the TransGo SK 4L60E valve body kit, listed here for 1993-2010 units except hybrids, which takes in the 2006-2010 Silverado, Sierra, Tahoe, Yukon and Trailblazer SS 4L70E years along with the earlier 4L60E and 4L65E trucks.
P1870 is a transmission component slipping code, and in this family it most often starts with the converter clutch. Sonnax explains that from 1998 on these units run EC3 converter control, which holds a controlled amount of slip rather than a hard lockup. The pulse-width modulated signal keeps the TCC regulator and isolator valves oscillating in their bore, the aluminum wears, apply pressure leaks away, and the computer reads too much slip. TransGo adds that the ECM then raises line pressure to protect the converter, which is where the hard 1-2 comes from.
This listing highlights the kit's ISO-CONV valve, a single drop-in valve that replaces both the factory isolator and converter regulator valves, with an added spacer for trucks with cylinder deactivation. No reamer or machining is needed. The kit also recalibrates the accumulators, servo and pressure regulator, and addresses the harmonic pressure bounce on the variable-displacement pump that wears the pump slide and valve bores.
Read freeze-frame data for the P1870 and check TCC slip rpm on the scan tool once the converter is commanded on. Steady high slip with a good converter points at the regulator and isolator bore. A bouncing pressure gauge supports the pump slide bounce diagnosis. Check that the pressure control solenoid amperage is in range before blaming the valve body; the EPC solenoid guide covers that test. For a broader look at no-lockup and TCC faults, see 4L70E common problems and fixes.
The listing names 1993-2010 GM 4L60E, 4L65E and 4L70E, except hybrid units. The 4L70E years within that window are 2006-2010. Trucks with Active Fuel Management cylinder deactivation use the spacer included for that purpose. TransGo also offers a separate HD2 reprogramming kit for heavy duty and performance builds; this standard kit is the right choice for a stock or towing truck that needs the factory problems fixed. Valve body and pump revisions changed during these years, so send your year and VIN if you want us to check. The rest of the hard parts are in the 4L70E collection.
The ISO-CONV valve and valve body springs go in with the pan and valve body removed, which can be done in the truck. The pump-related changes need the unit apart, so a rebuild is the ideal time. Work from TransGo's instructions, lay parts out in order, and torque the valve body bolts evenly. Fill with DEXRON-VI and check the level hot. Clear the codes and drive through several lockup cycles so the computer relearns. If the converter clutch circuit itself is suspect, replace the TCC solenoid while you are in there, and if harness wear shows near the reverse input drum, swap the internal wiring harness too.
| Fits | 4L70E 1993-2010 |
| Part type | Shift Kit |
| Condition | New |
| Brand | TransGo |
| Reference | P1870 |
| Ships | From the USA |
| Warranty | 1-year |
It targets the most common cause: TCC regulator and isolator bore wear that lets the converter slip. If the converter itself is damaged or the TCC solenoid is failing, the code can return, so test those too.
It is a one-piece drop-in valve in this kit that replaces both the factory isolator and converter regulator valves, so no reaming is required.
Yes. The kit includes a spacer added for vehicles with cylinder deactivation (Active Fuel Management).
For a heavily modified or performance build, TransGo recommends its HD2 reprogramming kit. For a stock or towing truck with P1870, a hard 1-2 or no lockup, this standard kit is designed for those complaints.
Clear codes, fill with DEXRON-VI, and drive through repeated shifts and lockup events so the computer adapts. A scan tool reset of shift adapts helps if your truck supports it.
