The engine capacity indicates the trans model is 4R44E.
As no diagnostic codes are present, the problem is most likely to be mechanical.
No reverse gears.
Check the following:
1. Fluid level.
2. Shift linkage.
3. Low line control pressure.
4. Filter assembly (plugged).
5. Valve body (sticking valves).
6. Incorrectly tightened valve body bolts (cross-leaks).
7. Low-reverse servo (piston seal leaking).
8. Direct and low-reverse clutch/band assemblies.
Tuesday, May 4th, 2021 AT 10:50 AM