u0121 : lost communication w ith the anti-lock brake

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DTC U0121: Lost Communication With The Anti-Lock Brake System (ABS) ControlModule

Description

The PSCM monitors the HS-CAN bus when the ignition has been on for more than 5 seconds, when thevoltage to the PSCM is greater than 9 volts and when there are no DTCs present that are inhibitingPSCM operation.

DTC U0121:00 (Lost Communication with the Anti-lock Brake System (ABS) Control Module: No SubType Information) - This DTC will set when communication between the PSCM and the ABS modulefails. The ABS module sends the following messages to the PSCM; steering angle, wheel speed, yawrate, stability control active and ABS active. If one or more of these messages is missing for morethan 1 second and the PSCM has not set DTC U0001:88, then the PSCM will set U0121:00.

Possible Causes

Fuse(s)Wiring, terminals or connectorsDTCs present in the ABS module

Diagnostic Aids

DTC U0121:00 indicates that the ABS module cannot communicate over the HS-CAN bus. This could bedue to a DTC being set in the ABS or a circuit fault in the HS-CAN bus. Do not install a new PSCM aspart of the repair for a PSCM DTC U0121:00.The presence of DTC U0121:00 will prevent the active park assist system and lane keep assist function(if equipped) from activating. If set during an active park assist event, the event will be terminated andthe active park assist system will deactivate. The driver may also experience the vehicle pulling to theleft or right during acceleration.

Action

CARRY OUT an ABS module self-test. If the diagnostic scan tool indicates the module is notresponding, REFER to MODULE COMMUNICATIONS NETWORK to DIAGNOSE the networkcommunication concern. If ABS module DTCs are present, REFER to ANTI-LOCK BRAKE SYSTEM(ABS) AND STABILITY CONTROL to DIAGNOSE the ABS system fault.

Introduction

This pinpoint test is intended to diagnose the following:

unable to communicate with powertrain control module (PCM)unable to activate the PCM self-testincorrect self-test procedureharness circuits: ISP-R, PCMRC, PWRGND and VPWR

YMMS: Mar 8, 2021Engine: 2.0L Eng License:VIN: Odometer:

2014 Ford Explorer Base



Fig 1: Identifying Electronic Throttle Body Throttle Position Sensor Connector Terminals

Courtesy of FORD MOTOR CO.

Vehicle Connector Pin Circuit

E-Series 6.8L, E-Series 5.4L, Expedition, Explorer GTDI 3.5L, F-Series Super Duty 6.8L,

A 3 2

ETCRTN ETCREF



Flex GTDI 3.5L, MKS 3.5L, MKT 3.5L, Motorhome/Stripped Chassis/Step Van, Mustang 5.8L, Navigator, Taurus GTDI 3.5L

E-Series 4.6L B 2 3

ETCRTN ETCREF

Escape 1.6L, Fiesta 1.6L, Fusion 1.5L, Fusion 1.6L, Transit Connect 1.6L

C 2 6

ETCRTN ETCREF

Fiesta 1.0L C 3 1

ETCRTN ETCREF

All other vehicles D 4 5

ETCRTN ETCREF

Powertrain Control Module (PCM) Connector

For PCM connector views or reference values, refer to SECTION 6: REFERENCE VALUES .

Vehicle Connector Pin Circuit

E-Series 4.6L, E-Series 5.4L 190-PIN

B22, B50, B69, B70 B30, B67, B68 B38 B42

PWRGND VPWR PCMRC ISP-R

E-Series 6.8L 190-PIN

B69, B70 B67, B68 B37 B42


Edge 2.0L, Explorer 2.0L, Focus

154 PIN

B1, B2, B4 B5, B6 B27 B15


Escape 1.6L, Escape 2.0L, Explorer GTDI 3.5L, Flex GTDI 3.5L, Fusion 1.5L, Fusion 1.6L, Fusion 2.0L, MKS 3.5L, MKT 2.0L, MKT 3.5L, MKZ 2.0L, Taurus 2.0L,

198 PIN B96, B97, B98, B99 B101, B102, B103 B58 B48




Taurus GTDI 3.5L, Transit Connect 1.6L

F-150 3.5L 198 PIN

B50, B96, B97, B98, B99 B101, B102, B103 B58 B48


F-650/F-750, F-Series Super Duty, Motorhome/Stripped Chassis/Step Van

190-PIN

B69, B70 B67, B68 B38 B42


Fiesta GTDI 1.6L, Fiesta 1.0L 198 PIN

B96, B97, B99 B101, B102, B103 B58 B48


Fiesta TiVCT 1.6L 128 PIN

B35, B36, B47, B48 B11, B12, E13, E37 B1 B8


All other vehicles 190-PIN

B50, B69, B70 B67, B68 B38 B42


Test Procedure

QA1 CARRY OUT A VEHICLE INSPECTION AND VERIFY THE SELF-TEST PROCEDURE

NOTE: If the self-test or communication concern occurred

after a failed or an aborted reprogram, the module may be

blank. Attempt to reprogram the module again before

continuing with this pinpoint test.

Visually inspect the following for obvious signs of electrical damage:harness wiringelectrical connections

Verify the correct procedure was used to activate the self-test for the scan tool. Refer to SCANTOOL SETUP AND FUNCTIONALITY .

Was the correct self-test procedure used?

Yes No

GO to QA2 . REFER to SCAN TOOL SETUP AND FUNCTIONALITY .

QA2 CARRY OUT THE NETWORK TEST



NOTE: When using Integrated Diagnostic System (IDS),

the scan tool attempts to communicate with the PCM first.

After establishing communication with the PCM, the scan tool

then attempts to communicate with all modules on the

vehicle. If an IDS session cannot be established, IDS may state

no communication can be established with the PCM:

choose No when the scan tool prompts whether or not to retry communication.enter a PCM part number, tear tag or calibration number to identify the vehicle and start asession. The PCM part number and 4-character tear tag are located on the PCM.Ignition ON, engine OFF.Carry out the network test.

Do all modules indicate pass?

Yes No

For DTCs U0101,U0402, U1011 orU1013, GO to QA7. For DTC U0104, GOto QA12. For DTCs U0121,U0415, U1012 orU1039, GO to QA8. For DTC U0138, GOto QA13. For DTCs U0140 orU0422, GO to QA9. For DTCs U0155 orU0423, GO to QA10. For DTC U0212, GOto QA11. For DTC U0298, GOto QA14. For all others,REFER to SECTION3: SYMPTOMCHARTS , GO toPinpoint Test QT .

If only PCM indicates fail, GO to QA3 . For network test or all other modules indicates fail, REFER to the applicableservice information article, Module Communications Network, to diagnose thePCM does not respond to the scan tool or no high speed controller areanetwork (CAN) communication, all modules are not responding symptom.

QA3 CHECK FOR VREF VOLTAGE AT THE ETBTPS SENSORIgnition ON, engine OFF.ETBTPS connector disconnected.Measure the voltage between:

(+) ETBTPS Connector, Harness Side (-) ETBTPS Connector, Harness Side

ETCREF ETCRTN



Is the voltage between 4.5 - 5.5 V?

Yes No

REFER to the applicable service information article, Module Communications Network, todiagnose the PCM does not respond to the scan tool or no high speed controller area network(CAN) communication, all modules are not responding symptom.

GOtoQA4.

QA4 CHECK THE ISP-R VOLTAGE AT THE PCMIgnition OFF.PCM connector disconnected.Ignition ON, engine OFF.Measure the voltage between:

(+) PCM Connector, Harness Side (-)

ISP-R Ground

Is the voltage greater than 10.5 V?

Yes No

GO to QA5 . REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test.

QA5 CHECK THE PCM VPWR CIRCUITS FOR VOLTAGEIgnition OFF.Disconnect the PCM.Connect a 5 amp fused jumper wire between the following:

Point A PCM Connector, Harness Side Point B

PCMRC Ground

Ignition ON, engine OFF.Measure the voltage between:


VPWR Ground

Is the voltage greater than 10.5 V?

Yes No

GO to QA6 . GO to PINPOINT TEST B.

QA6 CHECK THE PCM GROUND CIRCUITS FOR AN OPENIgnition OFF.Measure the resistance between:


PWRGND Ground



Is the resistance less than 5 ohms?

Yes No

GO to QA17. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test.

QA7 CHECK FOR A TRANSMISSION CONTROL MODULE (TCM) CONCERNCheck for any TCM DTCs.Check for other TCM related symptoms.

Is a concern present?

Yes No

REFER to the applicable Automatic Transaxle/Transmission article,DTC Charts to continue diagnosis.

For DTCs U1011 or U1013,GO to QA15. For all others, GO to QA17.

QA8 CHECK FOR AN ANTI-LOCK BRAKE SYSTEM (ABS) MODULE CONCERNCheck for any ABS module DTCs.Check for other ABS related symptoms.


Yes No

REFER to the applicable service information article, Vehicle DynamicSystems, DTC Charts to continue diagnosis.

For DTC U1012, GOto QA15. For all others, GO toQA17.

QA9 CHECK FOR A BODY CONTROL MODULE (BCM) CONCERNCheck for any BCM DTCs.Check for other BCM related symptoms.


Yes No

REFER to the applicable service information article, Multifunction Electronic Modules,DTC Charts to continue diagnosis.

GO toQA17.

QA10 CHECK FOR AN INSTRUMENT PANEL CLUSTER (IPC) CONCERNCheck for any IPC DTCs.Check for other IPC related symptoms.


Yes No

REFER to the applicable service information article, Instrumentation, Message Center, andWarning Chimes, DTC Charts to continue diagnosis.

GO toQA17.

QA11 CHECK FOR A CRUISE CONTROL CONCERNCheck for any other PCM DTCs.Check for other PCM related symptoms.




Yes No

Refer to the applicable service information article, Cruise Control to continue diagnosis ofthe cruise control system.

GO toQA17.

QA12 CHECK FOR A STEERING ANGLE SENSOR MODULE (SASM) CONCERNCheck for any SASM DTCs.Check for other SASM related symptoms.


Yes No

REFER to the applicable service information article, Vehicle Dynamic Systems to continuediagnosis of the SASM system.

GO toQA17.

QA13 CHECK FOR AN ALL TERRAIN CONTROL MODULE (ATCM) CONCERNCheck for any ATCM DTCs.Check for other ATCM related symptoms.


Yes No

REFER to the applicable service information article, Four Wheel Drive 4WD Systems tocontinue diagnosis of the ATCM system.

GO toQA17.

QA14 CHECK FOR A DC TO DC CONVERTOR CONTROL MODULE CONCERNCheck for any DC to DC convertor control module DTCs.Check for other DC to DC convertor control module related symptoms.


Yes No

REFER to the applicable service information article, Voltage Convertor/Invertor to continuediagnosis of the DC to DC control module system.

GO toQA17.

QA15 CHECK FOR A POWERTRAIN CONTROL MODULE (PCM) CONCERNCheck for any other PCM DTCs.


Yes No

DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the nextDTC. GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .

GO toQA16.

QA16 REFLASH THE PCMClear the PCM DTCs.Reprogram or update the PCM calibration. Refer to FLASH ELECTRICALLY ERASABLEPROGRAMMABLE READ ONLY MEMORY (EEPROM) , Programming the VID Block for aReplacement PCM.Road test the vehicle.



Carry out the PCM self-test.Verify the concern is still present.

Is the concern still present?

Yes No

For DTC U1012, REPROGRAM or UPDATE the ABS Calibration. REFERto the applicable service information article, Module Configuration. Clear the PCM DTCs. REPEAT the self-test. For all others, REPROGRAM or UPDATE the TCM Calibration. REFER tothe applicable service information article, Module Configuration. Clear the PCM DTCs. REPEAT the self-test.

The system is operatingcorrectly at this time.

QA17 CHECK FOR CORRECT PCM OPERATIONDisconnect all the PCM connectors.Visually inspect for:

pushed out pinscorrosion

Connect all the PCM connectors and make sure they seat correctly.Carry out the network test and verify the concern is still present.Carry out the PCM self-test.Verify the concern is still present.


Yes No

INSTALL a new PCM. REFER to FLASH ELECTRICALLYERASABLE PROGRAMMABLE READ ONLY MEMORY(EEPROM) , Programming the VID Block for a ReplacementPCM.

The system is operating correctly atthis time. The concern may have beencaused by a loose or corrodedconnector.

U0121 - LOST COMMUNICATION WITH ANTI-LOCK BRAKE SYSTEM (ABS)CONTROL MODULE

U0121 - LOST COMMUNICATION WITH ANTI-LOCK BRAKE SYSTEM (ABS) CONTROL MODULE

Description: The PCM continuously monitors the controller area network (CAN) for messages from theABS. This DTC sets when the PCM fails to receive the ABS message within the defined amount oftime.

Possible Causes:

Communication error

Diagnostic Aids: Check for other PCM DTCs or PCM related symptoms. Diagnose all other PCMDTCs or PCM related symptoms first.

Application Key On Engine Off Key On Engine Running Continuous Memory

All GO to PINPOINT TEST QA: UNABLE TO ACTIVATE SELF-TEST/NETWORKCOMMUNICATION ERROR .

U0121:00 Or U0129



Normal Operation And Fault Conditions

DTC FAULT TRIGGER CONDITIONS

DTC Description Fault Trigger Conditions

U0121:00

Lost CommunicationWith ABS ControlModule: No Sub TypeInformation

Sets in the C-CM if data messages received from the ABS moduleover the HS-CAN are missing.

U0129Lost CommunicationWith Brake SystemControl Module

Sets in the PCM if data messages received from the ABS moduleover the HS-CAN are missing. The adaptive cruise control isdeactivated if it does not receive an active braking message from theABS module.

PINPOINT TEST H: U0121:00 Or U0129

H1 VERIFY THE CUSTOMER CONCERNIgnition ON.Verify there is an observable symptom present.

Is an observable symptom present?

Yes : GO to H2 .

No : The system is operating normally at this time. The DTC may have been set due to highnetwork traffic or an intermittent fault condition.

H2 CHECK THE COMMUNICATION NETWORKIgnition ON.Using a scan tool, perform a network test.

Does theABSmodule pass the network test?

Yes : GO to H3 .

No : GO to PINPOINT TEST B .

H3 RETRIEVE THE RECORDEDDTCsFROM THEC-CM,ABSMODULE ANDPCMSELF-TESTSUsing a scan tool, perform the self-test on the following modules.

C-CMABS modulePCM

Are any low or high voltageDTCsrecorded?

Yes : For the C-CM , GO to PINPOINT TEST Q or GO to PINPOINT TEST R.For ABS module, GO to PINPOINT TEST A or REFER to GO to PINPOINT TEST P .For PCM , GO to PINPOINT TEST B (Diagnostic Trouble Code (DTC) P0562), or GO toPINPOINT TEST A (Diagnostic Trouble Code (DTC) P0563).

No : GO to H4 .

H4 RECHECK THEC-CMDTCsUsing a scan tool, clear the DTCs .Repeat the C-CM self-test.

IsDTCU0121:00 still present?



Yes : GO to H5 .

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

H5 CHECK FORDTCU0121:00 ORDTCU0129 SET IN OTHER MODULESUsing a scan tool, clear all DTCs .Ignition OFF.Wait 10 seconds.Ignition ON.Using a scan tool, perform Self-Test.Retrieve the continuous memory DTCs from all modules.

Do both theC-CMsetDTCU0121:00 and thePCMsetDTCU0129?

Yes : INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE.

No : INSTALL a new C-CM . Refer to Cruise-Control Module (C-CM).

U0121:00 [ Active Park Assist : Pinpoint Tests ]

Diagnostic Overview

Diagnostics in this service information assume a certain skill level and knowledge of Ford-specificdiagnostic practices. REFER to DIAGNOSTIC METHODS for information regarding Ford-specificdiagnostic practices.Refer to MODULE COMMUNICATIONS NETWORK for schematic and connector information.


The PAM communicates with the ABS module through the HS-CAN .DTC FAULT TRIGGER CONDITIONS


U0121:00Lost Communication WithABS Control Module: No Sub-Type Information

Sets in the PAM if data messages received from the ABSmodule over the HS-CAN are missing after the active parkassist system is activated.

PINPOINT TEST K: U0121:00

K1 VERIFY THE CUSTOMER CONCERNIgnition ON.Verify that there is an observable symptom present.


Yes : GO to K2 .


K2 CHECK THE COMMUNICATION NETWORKIgnition ON.Using a scan tool, perform network test.




Yes : GO to K3 .


K3 RECHECK THEPAMDTCsUsing a scan tool, clear the DTCs .Operate the system and test the system for normal operation.Using a scan tool, check the PAMDTCs .


Yes : GO to K4 .


K4 CHECK FORDTCU0121 ORDTCU0121:00 IN OTHER MODULESUsing a scan tool, clear all DTCs .Ignition OFF.Wait 10 seconds.Retrieve the CMDTCs from all modules.

IsDTCU0121 orDTCU0121:00 set in any module?

Yes : INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE.

No : GO to K5 .

K5 CHECK FOR CORRECTPAMOPERATIONDisconnect and inspect the PAM connector.Repair:

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

Reconnect the PAM connector. Make sure it seats and latches correctly.Operate the system and determine if the concern is still present.


Yes : CHECK OASIS for any applicable TSBs . If a TSB exists for this concern,DISCONTINUE this test and FOLLOW TSB instructions. If no TSBs address this concern,INSTALL a new PAM . REFER to PARKING AID MODULE (PAM) .

No : The system is operating correctly at this time. Concern may have been caused by moduleconnections. ADDRESS the root cause of any connector or pin issues.

U0121:00 [ Instrumentation, Message Center And Warning Chimes : Pinpoint Tests ]




U0121:00 Lost Communication With ABSControl Module: No Sub-TypeInformation

Sets in continuous memory in the IPC if data messagesreceived from the ABS module over the HS-CAN aremissing for 5 seconds or more.



PINPOINT TEST AU: U0121:00

AU1 VERIFY THE CUSTOMER CONCERNIgnition ON.Verify there is an observable symptom present.


Yes : GO to AU2 .


AU2 CHECK THE COMMUNICATION NETWORKIgnition ON.Using a scan tool, perform a network test.Carry out the network test.


Yes : GO to AU3 .

No : REFER to MODULE COMMUNICATIONS NETWORK .

AU3 RETRIEVE THE RECORDEDDTCsFROM THEABSMODULE SELF-TESTUsing a scan tool, perform the ABS module self-test.

IsDTCU3003:16 orDTCU3003:17 recorded?

Yes : REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL .

No : GO to AU4 .

AU4 RETRIEVE THE RECORDEDDTCsFROM THEIPCSELF-TESTUsing a scan tool, perform the IPC self-test.


Yes : For DTC U3003:16, GO to PINPOINT TEST BD.For DTC U3003:17, GO to PINPOINT TEST BE.

No : GO to AU5 .

AU5 RECHECK THEIPCDTCsClear the DTCs .Wait 10 seconds.Repeat the IPC self-test.


Yes : INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) ANDSTABILITY CONTROL . CLEAR the DTCs . REPEAT the IPC self-test. If DTC U0121:00 is stillpresent, INSTALL a new IPC . REFER to Instrument Panel Cluster (IPC).


U0121:00 [ Multifunction Electronic Modules : Pinpoint Tests ]

Diagnostic Overview



U0121:00




U0121:00Lost Communication With ABSControl Module: No Sub-TypeInformation

Sets in continuous memory in the BCM if data messagesreceived from the ABS module over the HS-CAN aremissing for 5 seconds or more.

PINPOINT TEST N: U0121:00

N1 VERIFY THE CUSTOMER CONCERNIgnition ON.Verify there is an observable symptom present.


Yes : GO to N2 .


N2 CHECK THE COMMUNICATION NETWORKUsing a scan tool, perform network test.

Does the ABS module pass the network test?

Yes : GO to N3 .


N3 RETRIEVE THE RECORDEDDTCsFROM THEBCMSELF-TESTUsing a scan tool, perform BCM self-test.Check for recorded BCMDTCs from the self-test.


Yes : For DTC U3003:16, GO to PINPOINT TEST H.For DTC U3003:17, GO to PINPOINT TEST I.

No : GO to N4 .

N4 CHECK FORDTCsU3003:16 AND U3003:17 FROM THE ABS MODULE SELF-TESTUsing a scan tool, retrieve the continuous memory DTCs from the ABS module.


Yes : For DTC U3003:16, GO to PINPOINT TEST A .For DTC U3003:17, GO to PINPOINT TEST P .

No : GO to N5 .

N5 RECHECK THEBCMDTCs



NOTE: If new modules were installed prior to the DTC

being set, the module configuration may be incorrectly set

during PMI or the PMI may not have been carried out.

Using a scan tool, clear the DTCs . Repeat the BCM self-test.IsDTCU0121:00 still present?

Yes : GO to N6 .


N6 CHECK FORDTCU0121:00 SET IN OTHER MODULESClear the DTCs .Ignition OFF.Ignition ON.Wait 10 seconds.Using a scan tool, retrieve the continuous memory DTCs from all modules.

IsDTCU0121:00 set in any other module?

Yes : INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE. CLEAR the DTCs .

No : INSTALL a new BCM . REFER to BODY CONTROL MODULE (BCM) - WITHINTELLIGENT ACCESS (IA) or REFER to BODY CONTROL MODULE (BCM) - WITHOUTINTELLIGENT ACCESS (IA).

Pinpoint Test N: Lost Communication U0121, U0129, U0415

Diagnostic Overview

Diagnostics in this service information assume a certain skill level and knowledge of Ford-specificdiagnostic practices. Refer to DIAGNOSTIC METHODS for information about these practices.Refer to MODULE COMMUNICATIONS NETWORK for schematic and connector information.


The TCM uses information contained in messages from the ABS module sent on the HS-CAN .DTC FAULT TRIGGER CONDITIONS


U0121 Lost Communication WithABS Control Module

This DTC sets if the TCM does not receive an expectedmessage from the ABS module.

U0129 Lost Communication WithBrake System Control Module

This DTC sets if the TCM does not receive an expectedmessage from the ABS module.

U0415 Invalid Data Received FromABS Control Module

This DTC sets if the TCM receives messages from the ABSmodule that are invalid or outside of an expected range.

Possible Sources



Connectors damaged or pushed-out terminals, corrosion, loose wires and missing or damaged sealsABS module

PINPOINT TEST N: LOST COMMUNICATION

N1 CHECK THE COMMUNICATION NETWORKIgnition ON.Enter the following diagnostic mode on the scan tool: Carry out the network test.

Did the ABS module pass the network test?

Yes : GO to N2 .

No : REFER to MODULE COMMUNICATIONS NETWORK to diagnose no communicationwith the ABS module.

N2 CHECK THETCMCMDTCsEnter the following diagnostic mode on the scan tool: Carry out the self-test and retrieve DTCs.Clear the DTCs.Wait 10 seconds.Repeat the self-test.

Are DTCs U0121, U0129 or U0415 present?

Yes : GO to N3 .


N3 RETRIEVE THE RECORDED DTCs FROM THETCMSELF-TESTCheck for recorded DTCs from the TCM self-test.

Are DTCs P0702, P0882, P0883, P0884 or P1397 present?

Yes : REFER to CHARGING SYSTEM .

No : GO to N4 .

N4 RETRIEVE THE RECORDED DTCs FROM THE ABS SELF-TESTCheck for recorded DTCs from the ABS self-test.

Are DTCs C1B14:11, C1B14:12 or C1B14:1C present?

Yes : REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL .

No : GO to N5 .

N5 CHECK FOR DTC U01210 SET IN OTHER MODULESIgnition ON.Enter the following diagnostic mode on the scan tool: Carry out the self-test for all modules.Retrieve the CMDTCs from all modules.

Is DTC U0121 set in the PCM or in theIPC?

Yes : CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, discontinue thistest and follow TSB instructions. If no TSBs address this concern, REFER to ANTI-LOCKBRAKE SYSTEM (ABS) AND STABILITY CONTROL .

No : CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, discontinue thistest and follow TSB instructions. If no TSBs address this concern, INSTALL a new TCM .REFER to TRANSMISSION CONTROL MODULE (TCM). PROGRAM the TCM with the latest



calibration level. PERFORM the Solenoid Body Strategy Download procedure. REFER toSOLENOID BODY STRATEGY DOWNLOAD.

Section 3: Symptom Charts

All diagnosis begins in Section 3 with QT Powertrain Control Module (PCM) Quick Test. If the PCMQuick Test is completed and no diagnostic trouble codes (DTCs) have been retrieved, the technician isdirected to the NO DIAGNOSTIC TROUBLE CODES (DTCS) PRESENT SYMPTOM CHART INDEX .The No Diagnostic Trouble Codes (DTCs) Present Symptom Chart Index contains the list of symptomsaddressed in this service information , and directs the technician to the appropriate chart in the NODIAGNOSTIC TROUBLE CODES (DTCS) PRESENT SYMPTOM CHARTS . If no PCM DTCs arepresent and the vehicle symptom is not listed in the No Diagnostic Trouble Codes (DTCs) PresentSymptom Chart Index, the technician should go to the appropriate Service Information article to continuediagnosis.

u0121 : lost communication w ith the anti-lock brake

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