Park at Deukmejian Parking Lot. Then hike up the main trail straight until you see the marked trail veering up to the right. That sign says Mt. Lukens and/or Crescenta View Trail. Continue 2 miles until you reach the large circle of rocks--a former camp site? There's very little shade on this trail so bring plenty of water, a hat, and sunscreen. There's a cache hidden and a shady spot after 1 mile up.
You can reach this cache from the trail!
You're looking for a cammo'd peanut butter jar.
In southern california wilderness, be aware of poison oak, ticks, rattlesnakes, etc.