The Isuzu 4HL1 is a 4.8-liter, turbocharged, direct-injection diesel engine found in medium-duty trucks like the Isuzu N-Series (NKR, NPR, NQR) and some FRR models. Unlike older mechanical injection pumps, the 4HL1 uses an ECD-V3 electronic control system manufactured by Bosch under license from Isuzu.
For a factory-accurate pinout, download the Isuzu ECD-V3 System Troubleshooting Manual (Pub. No. 5-17894-022.0). isuzu 4hl1 ecu pinout