Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC U1170-87: Lost Communication with Brake System Control Module (ch2) Missing Message [12/2024 - ]: Description
If there is a communication error between the engine stop and start ECU and electronically control brake system, the engine stop and start ECU stores DTCs and illuminates the stop and start cancel indicator.
HINT:
- When there is an open in the output side of the backup boost converter (built into the engine stop and start ECU), power to the system with the open is cut off. The engine stop and start ECU stores CAN communication DTCs for the system with the open stop and start system vehicle control history code X087A.
- When the backup boost converter (built into the engine stop and start ECU) detects overcurrent in any of the circuits it supplies power to, it shuts off the circuit. The engine stop and start ECU stores CAN communication DTCs for the system which circuit was shut off and stores stop and start system vehicle control history code X087A.
e.g.: When the backup boost converter (built into the engine stop and start ECU) detects overcurrent in the power source circuit of the skid control ECU (brake actuator assembly) and cuts off power supply, the engine stop and start ECU stores DTCs U0129-87 and vehicle control history code X087A.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Warning Indicate | Note |
|---|---|---|---|---|---|---|
| U1170-87 | Lost Communication with Brake System Control Module (ch2) Missing Message | No communication between the engine stop and start ECU and the skid control ECU (brake actuator assembly) for 2.22 second |
|
Does not come on | Blinks | SAE Code: U1170 |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.