4L60E Internal Transmission Wiring Harness, 2006-2008

This is the internal harness that runs inside the pan from the case connector to the shift solenoids, TCC and PWM solenoids, pressure control solenoid and pressure switch manifold on the valve body. It is listed for 2006-2008 Chevrolet, GMC and Pontiac vehicles with the 4L60E or 4L70E, and replaces GM 24234121 and aftermarket 350-0078.

Internal harness failures show up as intermittent codes that come and go with temperature: P0753, P0758, P0973 through P0976 shift solenoid circuit codes, TCC codes, or a truck that drops into limp mode (locked in a high gear) and then works fine after it cools. Old harnesses get brittle from heat, the insulation cracks where it flexes near the case connector, and the wires chafe against the valve body. Swapping solenoids will not fix it if the wiring is the problem.

To replace it, drop the pan and filter, unplug each solenoid and the pressure switch, release the case connector from the housing, and route the new harness along the same path with the retainers in place so it does not rub on the valve body. Check the case connector O-ring while you are there. Match the connector layout on your old harness before you install, since early 4L60E units use a different harness.