Pinpoint Test V: Abs Module Communication Concern With DCMR

WARNING: This page is about a different car, the 2023 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.

Normal Operation and Fault Conditions

With the ignition ON, the DCMR sends messages to the GWM over the HS-CAN1. The GWM relays these messages to the ABS module over the FD-CAN. If the ABS module does not receive these messages within the allotted time frame or if the messages contain invalid data, the module sets a DTC. This can be due to a DCMR failure, a circuit failure on the network or an excessive load on the network. For information on the messages sent to the ABS module by the DCMR, REFER to: Anti-Lock Brake System (ABS) and Stability Control - System Operation and Component Description .

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
ABS U0136:00	Lost Communication With Differential Control Module - Rear: No Sub Type Information	This DTC sets when the ABS module does not receive any messages from the DCMR within the allowed time.

Possible Sources

Network communication concern
GWM
DCMR

V1 CHECK THE COMMUNICATION NETWORK

Ignition ON.

NOTE: Diagnostic Trouble Codes (DTCs) may be displayed from previous diagnostic actions.

Using a diagnostic scan tool, carry out the Network Test.

Does the DCMR pass the Network Test?

Yes	RETRIEVE and RECORD all DCMR Diagnostic Trouble Codes (DTCs). REFER to: Rear Drive Axle and Differential - Vehicles With: Electronic Limited-Slip Differential . If there are no Diagnostic Trouble Codes (DTCs) in the DCMR module, GO to V3

GO to V2

V2 CHECK THE GWM COMMUNICATION

Review the results of the modules communicating on the network from the previous step.

Does the GWM pass the network test?

Yes	DIAGNOSE the DCMR module does not communicate with the diagnostic scan tool. REFER to: Controller Area Network (CAN) Module Communications Network .

No	DIAGNOSE the GWM module does not communicate with the diagnostic scan tool. REFER to: Controller Area Network (CAN) Module Communications Network .

V3 RECHECK THE ABS MODULE DIAGNOSTIC TROUBLE CODES (DTCS)

Using a diagnostic scan tool, clear the ABS module Diagnostic Trouble Codes (DTCs).

Ignition OFF.

Ignition ON.

Using a diagnostic scan tool, carry out the ABS module self-test.

Retrieve and record all ABS module Diagnostic Trouble Codes (DTCs).

Are any of the Diagnostic Trouble Codes (DTCs) in the Fault Trigger Conditions Table retrieved again?

Yes

GO to V4

No	The system is operating correctly at this time. The DTC was likely set due to high network traffic or an intermittent fault condition.

V4 CHECK FOR VOLTAGE DIAGNOSTIC TROUBLE CODES (DTCS) IN THE ABS MODULE
- Review the ABS module Diagnostic Trouble Codes (DTCs) retrieved in the previous step.
Is DTC U3003:16 or U3003:17 present?

Yes For DTC U3003:16, GO to Pinpoint Test A For DTC U3003:17, GO to Pinpoint Test F

No GO to V5

V5 RETRIEVE ALL DTCS FROM THE GWM
- Using a diagnostic scan tool, carry out the GWM self-test.
Are any Diagnostic Trouble Codes (DTCs) present?

Yes DIAGNOSE all GWM Diagnostic Trouble Codes (DTCs). REFER to: Controller Area Network (CAN) Module Communications Network .

No GO to V6

V6 RETRIEVE ALL DTCS FROM THE DCMR

Using a diagnostic scan tool, carry out the DCMR self-test.

Are any Diagnostic Trouble Codes (DTCs) present?

Yes	DIAGNOSE all DCMR Diagnostic Trouble Codes (DTCs). REFER to: Rear Drive Axle and Differential - Vehicles With: Electronic Limited-Slip Differential .

GO to V7

V7 CHECK FOR OTHER CAUSES OF COMMUNICATION NETWORK CONCERN

NOTE: If new modules were installed prior to the DTC being set, the module configuration can be incorrectly set during the PMI or the PMI may not have been carried out.

Check the vehicle service history for recent service actions related to the DCMR or the ABS module. If recent service history is found:
- Verify the correct replacement module was installed. HVBOM may be used to verify correct part fit.
- Verify the configuration of replacement module was correct. Re-configure the module using as-built data if prior configuration is suspect.
- Verify the module was not obtained from a like vehicle and installed into customer vehicle. Return the swapped module to source vehicle and obtain new replacement module.

Operate the system and determine if the observable symptom is still present.

Is the observable symptom still present?

Yes

GO to V8

No	The system is operating correctly at this time. The concern may have been due to incorrect parts replacement procedures or incorrect module configuration.

V8 CHECK FOR COMMUNICATION DIAGNOSTIC TROUBLE CODES (DTCS) IN OTHER MODULES
- Ignition ON.
- Using a diagnostic scan tool, carry out the Network Test.
Is U0136:xx present and active in 1 or more modules in addition to the ABS module?

Yes GO to V9

No GO to V10

V9 VERIFY DCMR OPERATION

Ignition OFF.

Disconnect all DCMR electrical connectors.

Disconnect all ABS module electrical connectors.

Disconnect all GWM electrical connectors.

Using a good light source, inspect all disconnected electrical connectors for the following:
- corrosion - install new connector or terminal and clean the module pins
- damaged or bent pins - install new terminals or pins
- pushed-out pins - install new pins as necessary
- spread terminals - install new terminals as necessary

Connect all GWM electrical connectors. Make sure the connectors seat and latch correctly.

Connect all ABS module electrical connectors. Make sure the connectors seat and latch correctly.

Connect all DCMR electrical connectors. Make sure the connectors seat and latch correctly.

Operate the system and verify the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no services articles address this concern, INSTALL a new DCMR. REFER to: Differential Control Module Rear (DCMR) .

No	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.

V10 VERIFY ABS OPERATION

Ignition OFF.

Disconnect all DCMR electrical connectors.

Disconnect all ABS module electrical connectors.

Disconnect all GWM electrical connectors.

Using a good light source, inspect all disconnected electrical connectors for the following:
- corrosion - install new connector or terminal and clean the module pins
- damaged or bent pins - install new terminals or pins
- pushed-out pins - install new pins as necessary
- spread terminals - install new terminals as necessary

Connect all GWM electrical connectors. Make sure the connectors seat and latch correctly.

Connect all ABS module electrical connectors. Make sure the connectors seat and latch correctly.

Connect all DCMR electrical connectors. Make sure the connectors seat and latch correctly.

Operate the system and verify the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no services articles address this concern, INSTALL a new EBB unit. REFER to: Electric Brake Booster (EBB) .

No	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.