2015 HINO 195 Won't Re-gen! Fault Code P0628 Present

likemlow · Jun 21, 2019

Hi all!! We just got Hino DX2 software (now I just have to learn how to use it) I'm trying to diagnose a P0628 Fault Code. Went through a trouble tree from Mitchell. Tested Ohms on the SCV was within spec, swapped it for another one anyway. Fuel Temp sensor was not within spec. - Replaced. Checked for voltage and ground on SCV connector - Present. Unplugged ECM harness and SCV connector, checked for ground short in harness- None present. Fault code still active. I've ran out of ideas. Anything I can do with the Hino scanner? Thanks for any input!!

Hino123 · Jun 23, 2019

Load test the wires with a load (test headlamp) while performing a "wiggle test" and verify the wires will hold a load. Check the pins in the connector at the SCV for corrosion and pin drag. You could check for a wire to wire short in the harness. I have never replaced a fuel temp sensor EVER on an Isuzu or Hino. Nor do I know anyone other than you that has changed one. Im personally curious what the out of specification was. Its a voltage related code so check your grounds and voltages. You can go into the engine and monitor the (actual common rail pressure) and (desired common rail pressure) also monitor "pump final value target" Record all 3. and take on a test drive to operating temp. Compare the actual to the desired pressures. They should be close. Then look at your pump final target valves when unit is warm. They should be in the 1670 ma to 1780 ma range. It sound like wiring not a mechanical component to me. I attached the description of the fault code below. Good luck

likemlow · Jun 26, 2019

Took forever but problem solved! One of the Pins on the SCV harness connector was pushing out ever so slightly. Even when we were probing the connector we didn't notice any movement. It was only when we plugged it into the SCV we noticed it. :dash2: