Lexus ES: Lost Communication with Brake System Control Module Missing Message (U012987)
MONITOR DESCRIPTION
The ECM and skid control ECU (brake booster with master cylinder assembly) send and receive signals via CAN communication.
If a communication error occurs between the ECM and skid control ECU (brake booster with master cylinder assembly), the ECM illuminates the MIL and stores this DTC.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory | Note |
|---|---|---|---|---|---|---|
| U012987 | Lost Communication with Brake System Control Module Missing Message | All of the following conditions are met for 4.98 seconds or more (1 trip detection logic):
|
| Comes on | DTC stored | SAE Code: U0129 |
MONITOR STRATEGY
| Related DTCs | U0129: Lost communication with brake system control module |
| Required Sensors/Components (Main) | ECM |
| Required Sensors/Components (Related) | - |
| Frequency of Operation | Continuous |
| Duration | 4.98 seconds |
| MIL Operation | Immediate |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
| Monitor runs whenever the following DTCs are not stored | None |
| Both of the following conditions are met | - |
| Auxiliary battery voltage | 10 V or higher |
| Power switch | On (IG) |
TYPICAL MALFUNCTION THRESHOLDS
| Communication signal | Lost communication with brake system control module |
CONFIRMATION DRIVING PATTERN
HINT:
-
After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.
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-
When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.
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- Connect the Techstream to the DLC3.
- Turn the power switch on (IG).
- Turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the power switch off and wait for at least 30 seconds.
- Turn the power switch on (IG) [A].
- Turn the Techstream on.
- Wait 5 seconds or more.
- Enter the following menus: Powertrain / Engine / Trouble Codes [B].
-
Read the pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine / Utility / All Readiness.
- Input the DTC: U012987.
-
Check the DTC judgment result.
Techstream Display
Description
NORMAL
- DTC judgment completed
- System normal
ABNORMAL
- DTC judgment completed
- System abnormal
INCOMPLETE
- DTC judgment not completed
- Perform driving pattern after confirming DTC enabling conditions
HINT:
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system is malfunctioning.
-
[A] to [B]: Normal judgment procedure.
The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.
- When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.
CAUTION / NOTICE / HINT
NOTICE:
-
Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.
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(Select Powertrain in Health Check and then check the time stamp data.)
Click here
-
If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.
Click here
HINT:
Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
| 1. | GO TO CAN COMMUNICATION SYSTEM |
(a) Refer to the CAN Communication System.
Click here
| NEXT | .gif) | END |
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Components
COMPONENTS ILLUSTRATION *A for HV Model - - *1 HYBRID VEHICLE CONTROL ECU *2 INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY WITH MAIN BODY ECU *3 NO. 3 INSTRUMENT PANEL TO COWL BRACE SUB-ASSEMBLY - - N*m (kgf*cm, ft.*lbf): Specified torque - - ILLUSTRATION *
Installation
INSTALLATION PROCEDURE 1. INSTALL BRAKE MASTER CYLINDER GASKET (a) Install a new brake master cylinder gasket to the brake booster with master cylinder assembly. 2. INSTALL BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (a) Install the brake booster with master cylinder assembly with the 4 nuts. Tor
