U1A00:87
Anti-Lock Control - Four-Channel
Pinpoint Test AF: DTC U1A00:49, U1A00:87, U1A00:88
Normal Operation
The yaw rate sensor, lateral and longitudinal accelerometers are contained in the Restraints Control Module (RCM). The RCM (Restraints Control Module) measures vehicle yaw rate, roll rate, lateral and longitudinal acceleration and then sends the information to the ABS module along a dedicated Controller Area Network (CAN). This dedicated CAN (Controller Area Network) is used only for communication between the RCM (Restraints Control Module) and the ABS module. The information sent to the ABS module is used to help determine if the AdvanceTrac(R) system needs to be activated.
- DTC U1A00:49 (Private Communication Network: Internal Electronic Failure)- this DTC sets in continuous memory and on demand when there is a communication issue between the ABS module and the RCM (Restraints Control Module).
- DTC U1A00:87 (Private Communication Network: Missing Message )- this DTC sets in continuous memory and on demand when expected messages such as yaw rate sensor, lateral accelerometer and longitudinal accelerometer missing for more than 5 seconds.
- DTC U1A00:88 (Private Communication Network: Bus Off )- this DTC sets in continuous memory and on demand when the communication bus is down between the ABS module and the RCM (Restraints Control Module) and they are unable to communicate.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- RCM (Restraints Control Module)
- ABS module
PINPOINT TEST AF : DTC U1A00:49, U1A00:87, U1A00:88
WARNING: Never probe the electrical connectors on air bag, Safety Canopy(R) or side air curtain modules. Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
AF1 CHECK FOR AN HS-CAN (High Speed Controller Area Network) CONCERN WITH THE RCM (Restraints Control Module)
- Ignition ON.
- NOTE: The Network Test does not test the dedicated CAN (Controller Area Network) communications between the ABS module and RCM (Restraints Control Module).
Using a scan tool, carry out the Network Test.
Does the RCM (Restraints Control Module) pass the Network Test?
Yes
GO to AF2.
No
REFER to Information Bus to diagnose the RCM (Restraints Control Module) does not respond to the scan tool.
AF2 VERIFY THE RCM (Restraints Control Module) PART NUMBER
- Using a scan tool, retrieve and record the RCM (Restraints Control Module) part number from the log viewer.
- Check the part number recorded against the number listed in the parts catalog.
Does the part number on the RCM (Restraints Control Module) match the part number listed in the parts catalog?
Yes
GO to AF3.
No
INSTALL the correct RCM (Restraints Control Module). CLEAR the DTCs. REPEAT the self-test.
AF3 CHECK THE DEDICATED CAN (Controller Area Network) CIRCUITS FOR A SHORT TO VOLTAGE
- Depower the Supplemental Restraint System (SRS). Refer to Restraints and Safety Systems &/or Air Bag Systems.
- Disconnect: RCM (Restraints Control Module) C310B.
- Disconnect: ABS Module C135.
- Connect: Battery Negative Cable.
- Ignition ON.
- Measure the voltage between the ABS module C135, harness side and ground as follows:
ABS Module Circuit C135-8 VCA23 (BU/WH) C135-9 VCA24 (GN/OG)
Is any voltage present?
Yes
REPAIR the affected circuit(s) for a short to voltage. CLEAR the DTCs. REPEAT the self-test.
No
GO to AF4.
AF4 CHECK THE DEDICATED CAN (Controller Area Network) CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the ABS module C135, harness side and ground as follows:
ABS Module Circuit C135-8 VCA23 (BU/WH) C135-9 VCA24 (GN/OG)
Are the resistances greater than 10,000 ohms?
Yes
GO to AF5.
No
REPAIR the affected circuit(s). TEST the system for normal operation.
AF5 CHECK THE DEDICATED CAN (Controller Area Network) CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between ABS module C135-9, circuit VCA24 (GN/OG), harness side and ABS module C135-8, circuit VCA23 (BU/WH), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to AF6.
No
REPAIR the circuits. CLEAR the DTCs. REPEAT the self-test.
AF6 CHECK THE DEDICATED CAN (Controller Area Network) CIRCUITS FOR AN OPEN
- Measure the resistance between the ABS module C135, harness side and the RCM (Restraints Control Module) C310B, harness side as follows:
ABS Module Circuit RCM (Restraints Control Module) C135-8 VCA23 (BU/WH) C310B-20 C135-9 VCA24 (GN/OG) C310B-19
Are the resistances less than 5 ohms?
Yes
GO to AF7.
No
REPAIR the affected circuit(s). CLEAR the DTCs. CYCLE the ignition key. REPEAT the self-test.
AF7 CHECK FOR CORRECT RCM (Restraints Control Module) OPERATION
- Disconnect: RCM (Restraints Control Module) Connectors.
- Check for:
- corrosion
- pushed-out pins
- spread terminals
- Connect: RCM (Restraints Control Module) Connectors.
- Make sure the connectors are seated correctly.
- Repower the SRS (Supplemental Restraint System). Refer to Restraints and Safety Systems &/or Air Bag Systems.
- Operate the system, verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new RCM (Restraints Control Module). CLEAR the DTCs. REPEAT the self-test.
If DTCs U1A00:49, U1A00:87 or U1A00:88 are retrieved again, GO to AF8.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
AF8 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect: ABS Module.
- Check for:
- corrosion
- pushed-out pins
- spread terminals
- Connect: ABS Module.
- Make sure the connector is seated correctly, then operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module . TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.