Is taking a kid rock climbing in a jeep child endangerment?

If it is your kid or you have the parent's permission and proper safety precautions are made then this is not endangerment. You are looking at trouble when you end up with a seriously injured child/dead kid and there is alcohol involved, a lack of safety gear, or clear lack of providing adequate safety (child not strapped in) or engaging in excessively dangerous activity. Most likely you are a divorcee not wanting their ex to take the child on these excursions and you want to make the case that this is endangerment to control the ex's activities with or ability to see the kids in which case you don't have a case and the truth of the matter is that you can not control what your ex does with your kids during their time unless it is abusive or neglectful. You may not like this activity but done correctly it is probably far more dangerous for you to let a kid ride a bike without a helmet than to occasionally rock climb in a jeep.