8L90 Internal Wiring Harness 2015, new and ready to install. Fits the 8L90. Ships fast from the USA.
This is a new genuine GM 24045609 internal harness for the 8L90 and 8L45 eight-speeds, 2015 and up. It is the part shops reach for when a Silverado, Sierra, Tahoe, Yukon, Escalade, Camaro, Corvette, Colorado or Canyon sets P0711 for the fluid temperature sensor, drops into failsafe now and then, or throws range or solenoid circuit codes that come and go with heat and vibration. GM bulletin PIP5700F lists 24045609 as the pass-through harness, item 37, the section that runs from the round case connector into the transmission.
The 8L90 and 8L45 TCM is mounted outside the transmission, so every signal the unit sends or receives passes through this wiring: nine solenoids on the valve body, the fluid temperature sensor, speed sensors and the internal mode switch that reports the shifter position. Transmission Digest explains that the harness has changed several times. It launched as a two-piece design, a pass-through case connector section joined to an internal harness at the X176 connector, went to a one-piece harness around 2019, then returned to two pieces in 2020 when GM switched the internal mode switch from 10 pins to 4. GM no longer supplies the one-piece harness, so any replacement now is the two-piece setup. The listing describes a 27-blade round case connector with 22-prong and 6-prong connectors inside.
Unplug the case connector and look for fluid, green corrosion, spread or pushed-back terminals. GM guidance for one range-sensor fault is to reconnect the pass-through connector first and replace the harness only if the condition returns. Watch fluid temperature on a scan tool from a cold start; a reading that jumps or sticks points at the sensor circuit. Our 8L90 solenoid symptoms guide covers resistance checks at the case connector, and 8L90 common problems and fixes separates wiring faults from hydraulic ones.
PIP5700F lists 24045609 as the pass-through harness for non stop/start (non-ESS) applications with either the 10-pin or the 4-pin mode switch. Vehicles with stop/start use a different pass-through (24298759 or 24045608). The valve body harness, item 313, is a separate part (24046895 for 10-pin, 24046896 for 4-pin) and is not included. Transmission Digest warns GM pinouts for 2020-up connectors contain errors and that a mismatched pass-through will set codes at once; a 10-pin connector has four large terminals at the center of the X176 connector, a 4-pin has three. Check your old part number, or send us your year and VIN. The rest of the family is in our 8L90/8L45 collection.
Drain the fluid, drop the pan and remove the valve body for access. Mark every solenoid connector before you unplug it. Sonnax traced a 3-4 neutral to the S8 and S9 connectors being swapped during a harness job: the two solenoids are identical and use the same plug, so match S8 to the 3.75 inch conduit lead on terminal 1 and S9 to the 1.75 inch lead on terminal 7. Release the case connector, install the new harness with fresh seals, and route it clear of the moving parts. While the valve body is out, consider the 8L90 valve body solenoid set if your codes have pointed at solenoids, and install a new filter and steel pan gasket kit. Refill with DEXRON HP (GM lists 7.4 quarts for a fluid change), set level hot, clear codes and run the adaptive relearn.
| Fits | 8L90 2015 |
| Part type | Internal Wiring Harness |
| Condition | New |
| Brand | GM |
| Reference | 24045609 |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
GM bulletin PIP5700F lists 24045609 as the pass-through harness, item 37, the section that carries the round case connector. The valve body harness is a separate part number.
No, according to PIP5700F. 24045609 is listed for non-ESS (no stop/start) applications. Stop/start vehicles use 24298759 or 24045608 depending on the mode switch.
P0711 fluid temperature codes, intermittent failsafe, range or mode switch codes, and solenoid circuit codes that move between solenoids. Fluid in the case connector is a common find.
Many shops replace both. PIP5700F pairs this pass-through with valve body harness 24046895 (10-pin mode switch) or 24046896 (4-pin), which is sold separately.
Swapping the S8 and S9 solenoid connectors. Sonnax traced a 3-4 neutral to that error; S8 connects to terminal 1 on the 3.75 inch lead and S9 to terminal 7 on the 1.75 inch lead.
