05 GMC Safari wouldn't start.

lld39

3 weeks ago wouldn't start / crank / nothing. All electrical working. 3 hours later started. 3 days ago same problem had towed to shop. Started they tested stuff couldn't find any problems. Any ideas ?

elias

inspect wire/connections inbetween positive battery post and starter for any corrosion/issue. also you can parallel that wire with a single jumper cable to see if that cures a starter-won't-engage/no-crank condition.
could be flakey/intermittent starter-motor or solenoid. next time no-start occurs, maybe you can try giving a couple solid raps on the starter motor with a tire iron while someone tries to start it, to prod the solenoid to kick out the starter motor gear.