Pinpoint Test S: DTC (Diagnostic Trouble Code) U0253:87

Refer to Module Communications Network for schematic and connector information.

Normal Operation and Fault Conditions

The IPMB communicates with the APIM through the HS-CAN2, GWM and HS-CAN1.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
IPMB U0253:87	Lost Communication With Accessory Protocol Interface Module: Missing Message	Sets in continuous memory in the IPMB if expected messages from the APIM are not received for 5 seconds or more when the ignition is on.

Possible Sources

Communication network concern
APIM concern
IPMB concern
GWM concern

S1 VERIFY THE CUSTOMER CONCERN

Ignition ON.

Verify whether an observable symptom present.

Is an observable symptom present?

Yes

GO to S2

No	CLEAR the DTC. The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.

S2 CHECK THE COMMUNICATION NETWORK
- Using a diagnostic scan tool, perform the network test
Does the APIM pass the network test?

Yes GO to S3

No Refer to: Communications Network .

S3 PERFORM THE APIM (SYNC MODULE) SELF-TEST

Using a diagnostic scan tool, perform the APIM self-test.

Are any non-network Diagnostic Trouble Codes (DTCs) recorded?

Yes	DIAGNOSE all non-network Diagnostic Trouble Codes (DTCs). Refer to: Information and Entertainment System .

GO to S4

S4 CHECK THE GWM (GATEWAY MODULE A) DIAGNOSTIC TROUBLE CODES (DTCS)
- Using a diagnostic scan tool, check the GWM Continuous Memory Diagnostic Trouble Codes (CMDTCs).
Are any Diagnostic Trouble Codes (DTCs) recorded?

Yes Refer to: Communications Network .

No GO to S5

S5 PERFORM THE IPMB (IMAGE PROCESSING MODULE B) SELF-TEST

Using a diagnostic scan tool, perform the IPMB self-test.

Are any Diagnostic Trouble Codes (DTCs) recorded?

Yes	DIAGNOSE all non-network Diagnostic Trouble Codes (DTCs). Refer to the DTC Chart: IPMB .

GO to S6

S6 RECHECK THE IPMB (IMAGE PROCESSING MODULE B) CONTINUOUS MEMORY DIAGNOSTIC TROUBLE CODES (CMDTCS)

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

Ignition OFF.

Ignition ON.

Wait 10 seconds.

Retrieve the IPMB Continuous Memory Diagnostic Trouble Codes (CMDTCs).

Is DTC U0253:87 still present?

Yes

GO to S7

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

S7 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 APIM or IPMB. If recent service history is found:
- verify correct replacement module was installed
  - vehicle parts build list may be used to verify correct part fitment
- verify the configuration of replacement module was correct
  - re-configure 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 S8

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

S8 CHECK FOR CORRECT APIM (SYNC MODULE) OPERATION

Ignition OFF.

Disconnect and inspect the APIM connectors.

Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary

Reconnect the APIM connectors. Make sure they seat and latch correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes

CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a Technical Service Bulletin (TSB) exists for this concern, DISCONTINUE this test and FOLLOW the Technical Service Bulletin (TSB) instructions. If no Technical Service Bulletins (TSBs) address this concern, refer to APIM GUIDED ROUTINE

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.