Use alfaOBD and an OBDLinkMX+ bluetooth scanner with an android device to check for fault codes from ALL modules. Many scanners do not read the ABS and Steering modules, and many of those codes do not set a CEL. A faulty module will not communicate and that sets a network code. If you don't understand the CAN C Bus Network, take it to someone that does. This isn't something you just throw parts at.

28 - DTC-Based Diagnostics / MODULE, Body Control (BCM) / Diagnosis and Testing

U0131-87-LOST COMMUNICATION WITH ELECTRIC POWER STEERING MODULE - MISSING MESSAGE

Theory of Operation

The primary communication network between electronic control modules is the Controller Area Network (CAN) data bus system. The Controller Area Network (CAN) data bus allows all electronic modules connected to the bus to share information with each other. Regardless of whether a message originates from a module on the higher speed CAN C (500K) Bus or on the lower speed bus, CAN Interior High Speed (IHS) (125K) Bus, the message structure and layout is similar, which allows the Body Control Module (BCM) to process and transfer messages between the CAN buses. The BCM stores Diagnostic Trouble Codes (DTCs) for certain bus network faults on the CAN C (500K) Bus and CAN IHS (125K) Bus.

The CAN bus modules are connected in parallel to the two-wire bus using a twisted pair, where the wires are wrapped around each other to provide shielding from unwanted electromagnetic induction, thus preventing interference with the relatively low voltage signals being carried through them. While the CAN bus is operating (active), one of the bus wires will carry a higher voltage and is referred to as the CAN High or CAN bus (+) wire, while the other bus wire will carry a lower voltage and is referred to as the CAN Low or CAN bus (-) wire.

For additional information on the communication network and star connector locations, (Refer to 08 - Electrical/8E - Electronic Control Modules/COMMUNICATION - Description).

•When Monitored:
With the ignition on for at least five seconds.

Battery voltage between 10 and 16 volts.

Body Control Module (BCM) is configured correctly.

•Set Condition:
Bus messages not received from the Electric Power Steering Module (EPS) for approximately two to five seconds.

Possible Causes

CAN C BUS (+) CIRCUIT SHORTED TO VOLTAGE
CAN C BUS (-) CIRCUIT SHORTED TO GROUND
DTCS RELATED TO BATTERY VOLTAGE, IGNITION, OR VIN MESSAGES
BCM NOT CONFIGURED CORRECTLY
EPS POWER AND GROUND
ELECTRIC POWER STEERING MODULE (EPS)
MODULE THAT SET THIS DTC

1.VERIFY DTC IS ACTIVE

NOTE: Make sure the battery voltage is between 10 and 16 volts before proceeding.

1. With the scan tool, read active DTCs.

Is this DTC active?

Yes

•Go To 2

No

•(Refer to 29 - Non-DTC Diagnostics/Communication - Diagnosis and Testing) and perform the Stored Lost Communication DTCs diagnostic procedure.


2.CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS

1. With the scan tool, read all active DTCs from all modules.

NOTE: Check for BCM configuration, CAN C hardware electrical, VIN Missing/Mismatch, battery or ignition related DTCs.

Does the scan tool display any active DTCs to the conditions listed above?

Yes

•(Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Diagnosis and Testing) and perform the appropriate diagnostic procedure.

No

•Go To 3


3.VERIFY THE ELECTRIC POWER STEERING (EPS) MODULE IS ACTIVE ON THE BUS

1. Turn the ignition on.

2. With the scan tool, verify the EPS Module is active on the bus.

Is the EPS Module active on the bus?

Yes

•Go To 4

No

•(Refer to 29 - Non-DTC Diagnostics/Communication - Diagnosis and Testing) and perform the NO RESPONSE FROM EPS MODULE (ELECTRIC POWER STEERING MODULE) diagnostic procedure.


4.CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS

1. With the scan tool, read all the DTCs.

Is there more than one module with active DTCs “Logged Against” the EPS Module?

Yes

•Replace/update the Electric Power Steering (EPS) Module in accordance with the Service Information.
•Perform the EPS MODULE VERIFICATION TEST. Refer to 28 - DTC-Based Diagnostics/MODULE, Electric Power Steering (EPS) /Standard Procedure.

No

•Go To 5


5.CLEAR DTC IN MODULE SETTING FAULT

1. With the scan tool, select the module setting the DTC against the EPS Module.

2. Clear active DTCs.

Is this DTC still active?

Yes

•Replace/update the module that set this DTC in accordance with the Service Information.
•Perform the appropriate verification test for the module being replaced. If there is no verification test for the associated module perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Body Control (BCM) - Standard Procedure).

No

•Go To 6


6.CYCLE IGNITION

1. Cycle the ignition from RUN to OFF three times ending with the key in the RUN position.

Does this DTC become active?

Yes

•Go To 7

No

•The condition is not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched and partially broken wires and the wiring harness connectors for broken, bent, pushed out and corroded terminals.
•Perform the appropriate verification test for the module. If there is no verification test for the associated module perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Body Control (BCM) - Standard Procedure).


7.CHECK FOR ADDITIONAL LOST COMMUNICATION FAULTS

1. With the scan tool, view the modules.

Does the BCM and other CAN C BUS modules show Lost Communication with the remaining CAN C BUS modules?

Yes

•Go To 8

No

•Replace/update the module that set this DTC in accordance with the Service Information.
•Perform the appropriate verification test for the module being replaced. If there is no verification test for the associated module perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Body Control (BCM) - Standard Procedure).


8.CHECK THE CAN C BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE

1. Measure the voltage between the (D57) CAN C Bus (+) circuit and ground.

Is the voltage above 5.0 volts?

Yes

•Repair the short to voltage in the CAN C Bus (+) circuit. The short to voltage is present in one of the CAN C Bus circuits. Use the Star Connectors to isolate portions of the CAN C Bus in order to locate the concern.
•Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Body Control (BCM) - Standard Procedure).

No

•Go To 9


9.CHECK THE CAN C BUS (-) CIRCUIT FOR A SHORT TO GROUND

1. Turn the ignition off.

2. Measure the resistance between ground and the (D58) CAN C Bus (-) circuit.

Is the resistance below 10k Ohms?

Yes

•Repair the short to ground in the CAN C Bus (-) circuit. The short to ground is present in one of the CAN C Bus circuits. Use the Star Connectors to isolate portions of the CAN C Bus in order to locate the concern.
•Perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Body Control (BCM) - Standard Procedure).

No

•Replace/update the module that set this DTC in accordance with the Service Information.
•Perform the appropriate verification test for the module being replaced. If there is no verification test for the associated module perform the BODY VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Body Control (BCM) - Standard Procedure).



28 - DTC-Based Diagnostics / MODULE, Antilock Brake (ABS) / Diagnosis and Testing

U0401-00-IMPLAUSIBLE DATA RECEIVED FROM ECM/PCM
.
NOTE:
Check for DTCs in the associated module before continuing with this diagnostic procedure.

When Monitored and Set Conditions

When Monitored: This diagnostic runs continuously when the following conditions are met:

•Ignition on.
•System voltage between 10.0 and 16.0 volts.
•One valid CAN message received at least once.
•No U0002-88-CAN C Bus Off Performance DTC present.

Set Conditions:

•Anti-lock Brake System (ABS) Module detects an incorrect CAN message from the Powertrain Control Module (PCM).

Default Actions:

•ABS is disabled.

Possible Causes

ANTI-LOCK BRAKE SYSTEM (ABS) MODULE CAN BUS DTCS
POWERTRAIN CONTROL MODULE (PCM) CAN BUS DTCS
ANTI-LOCK BRAKE SYSTEM (ABS) MODULE
POWERTRAIN CONTROL (PCM)

1.CHECK FOR AN ACTIVE DTC

NOTE: This DTC must be active for the results of this test to be valid.

1. Perform any Service Bulletins that may apply.

2. Turn the ignition on.

3. With the scan tool, read ABS DTCs and record on the repair order.

4. Cycle the ignition switch from off to on.

5. With the scan tool, read ABS DTCs.

Is the DTC active?

Yes

•Go To 2

No

•Perform the ABS-INTERMITTENT CONDITION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).


2.CHECK IF POWERTRAIN CONTROL MODULE DTCS ARE PRESENT

1. With the scan tool, read the PCM DTCs.

Are there any PCM DTCs present?

Yes

•Perform the appropriate diagnostic procedures. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Diagnosis and Testing).

No

•Go To 3


3.CHECK OTHER MODULES FOR CAN BUS DTCS

1. With the scan tool, read the DTCs.

Are there any CAN BUS DTCs present?

Yes

•Using the schematics as a guide, check the Powertrain Control Module (PCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the Powertrain Control Module (PCM) in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control/Removal) .

No

•Using the schematics as a guide, check the Anti-lock Brake System (ABS) Module pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the Anti-lock Brake System (ABS) Module in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Anti-Lock Brake System - Removal) .
•Perform the ABS VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Anti-Lock Brake (ABS) - Standard Procedure) .

 

It's not the PCM. Those are network codes. Do proper diagnosis.