U0100 Howo / Shacman — lost ECM comms, causes and repair

Fault codes / U0100

Cluster, gearbox, ABS do not see the ECM. Often power or a broken CAN in the cab-to-frame loom, not a dead brain.

Which trucks see it

WD615, WP10–WP13, MC11, ISM11. Nearby: U0155 cluster, U0101 TCM.

Symptoms

• scan tool cannot talk to engine
• dead tach
• no start
• gearbox limp

Likely causes

• No ECM power/ground, fuse.
• CAN-H/L open.
• ECM itself — after power and bus check out.

What to check

1. Power and ground at the ECM plug.
2. 60 ohm CAN with key off.
3. Cab-frame flex on Howo/Shacman.
4. See if ECM is visible alone.

Can you keep driving

No start or no gears — tow. One-off after a wash — you can drive, then fix the loom.

Look up the code in the service

Other codes

• P0087 — low common-rail pressure
• P0193 — rail pressure sensor high signal
• P0299 — boost below target
• P0335 — crankshaft sensor no signal
• P0401 — EGR insufficient flow
• P0562 — system voltage low
• P0201 — cylinder 1 injector circuit
• P0116 — water in fuel (Weichai table) / not always coolant SAE
• P2509 — intermittent ECM power (no OEM in DB)