: Signals sent to the fuel injectors and Suction Control Valve (SCV).
If your 4HL1 engine cranks but won't start, focus your testing on these areas: Isuzu 4HL1 Engine Control Manual | PDF | Hypertext - Scribd isuzu 4hl1 ecu pinout link
: Essential for the ECM to wake up and operate. : Signals sent to the fuel injectors and