Weak battery or poor connections
Your Jeep Grand Cherokee's transmission can go into limp mode if you are using a weak battery. You should check the battery and cables from both ends, battery and car. If the limp mode is caused by bad battery then you can upgrade the Transmission Control Module software at your dealer. This upgrade won't make your battery better, but does not allow TCM to go into limp mode cause of under voltage. To avoid starting problems in future, you should still change the battery soon.

4. Gearbox plug adapter, OEM 68021352AA


Transmission plug adapter is located under the car and often starts leaking oil. Once oily, the plugs have bad electrical connection and transmission goes into limp mode and starts showing fault codes. It is easy to check the plug - look under the car and check if the plug is oily. If it's oily - get it replaced. Also check if the cables are fine - with time the insulation can crack and cables can short circuit. Then the outcome is again P0702 and limp mode. You can easily fix it with some tape.