First-round leader Brendan Steele posted a 4-under 68 and is one shot back at minus-12. Scott Gibson also carded a 68 to move into third at 11-under-par 133. Anthony Rodriguez was 4 under par for his second round and that left him in fourth at minus-10.
Griff opened with a birdie on the first. He ran off four birdies in a five-hole span from the fifth at Glendale Golf & Country Club to jump to 12 under.
The 34-year-old stumbled to a bogey on the 10th after missing the green left, but recovered that stroke with a birdie on No. 14. Griff posted his final birdie on the 17th to grab the lead.
'I've been feeling good about things and am still putting well,' Griff admitted. 'But it's still only two days. I'll get up Saturday, have a good breakfast, come out and play and see what happens.'
Steele slipped to a bogey on the second to open his round. He ran off three straight birdies from the fifth to climb to minus-10.
The 23-year-old parred his next six holes. He got to 11 under with a birdie at 14, then moved within one of the lead with a birdie on No. 17.
'I was just trying to go out and do the same thing,' Steele said of his round. 'I didn't want to think about where I was compared to everyone else. There is too much time left.'
Michael Sims, Eugene Smith and Ryan Miller share fifth place at 9-under-par 135. Rusty Kennedy is one stroke further back at minus-8.
Stephen Gangluff fired a 7-under 65 to join Wil Collins and Daniel DeLeon in ninth place at 7-under-par 137. Defending champion Matt McQuillan is one stroke further back at minus-6 and tied for 12th.
The cut fell at 1-under-par 143 with 67 players advancing to the final two rounds.