Service Bulletin Date: March, 2012

1 Copyright 2012 General Motors LLC. All Rights BulletinFile in Section: 07 - Transmission/TransaxleBulletin No.: 08-07-30-021 GDate: March, 2012 TECHNICALS ubject: Loss of High Speed GMLAN Communications, Intermittent No Crank, IP GageFluctuation, Intermittent Door Lock Cycling, Intermittent Chime Operation, Various IPWarning Lamps Illuminated, Transmission May Not Shift, Communication DTCs U0073,U0100, U0101, U0102, U0109, U0121 or U0140 Set (Repair Terminals in TransmissionHarness Connector, Repair Open or Shorted GM High Speed LAN Circuits, Open orShorted Data Link Resistor, Corrosion or Poor Connections in Various Control ModuleConnectors)Models: 2007 2010 Cadillac XLR2007 2012 Cadillac Escalade Models2009 2012 Cadillac Escalade Hybrid2007 2012 Chevrolet Avalanche, Corvette, Silverado, Suburban, Tahoe2008 2012 Chevrolet Silverado Hybrid, Tahoe Hybrid2007 2012 GMC Sierra, Yukon Models2008 2012 GMC Sierra Hybrid, Yukon Hybrid2008 2009 HUMMER H2 Equipped With Gasoline Engine and 6 Speed Automatic Transmission 6L80 (RPO MYC)or 6L90 (RPO MYD)Equipped With Hybrid Propulsion (RPO HP2) and Two Mode 2ML70 AutomaticTransmissionThis Bulletin is being revised to add the 2012 model year and additional Correctioninformation.

2 Please discard Corporate Bulletin Number 08-07-30-021F(Section 07 Transmission/Transaxle).ConditionSome customers may comment on any of the followingconditions: The malfunction indicator lamp (MIL) may beilluminated. Instrument panel cluster (IPC) warning lamps mayilluminate. The transmission may not shift or defaults to2nd gear. The door locks may cycle by themselves. The engine may not crank intermittently. A driver information center (DIC) message may bedisplayed. The IPC gages may fluctuate. Applying the brakes may cause the IPC tobecome erratic and the chimes to on the vehicle and build, technicians mayfind one or more, but not limited to the following, HighSpeed GMLAN Communication DTCs set as Current orHistory: P0700: Transmission Control Module (TCM)Requested MIL Illumination. U0073: Control Module CommunicationsBus OFF. U0100: Lost Communication With ECM/PCM. U0101: Lost Communication With TransmissionControl Module (TCM).

3 U0102: Lost Communication with Transfer CaseControl Module (TCCM). U0109: Lost Communication With Fuel PumpControl Module. U0121: Lost Communication With ABS ControlModule. U0140: Lost Communication With Body ControlModule (BCM). U186B: Lost Communication With 2 March, 2012 Bulletin No.: 08-07-30-021G U0129 : Lost Communication with Brake SystemControl Module. U186B: Lost Communication with TCM. U0293: Lost Communication with HP2 PowertrainControl Module. U1862: Battery Energy Control Module LostCommunication with Communications GatewayModule. U1886: Battery Energy Control Module LostCommunication with Engine ControlModule (ECM). U1888: Hybrid Powertrain Control Module LostCommunication With Starter/Generator conditions may be caused by, but not limited to,any of the following: Chafed, damaged, pinched, open or shortedwiring. The terminal(s) for the High Speed GMLAN SerialData Bus has or have backed out of the 16-wayelectrical connector to the automatic transmission.

4 The terminal position assurance (TPA) lock in thetransmission 16-way electrical connector is notfully seated. The High Speed GMLAN Serial Data Bus circuitsare open or shorted to ground. Corrosion in a control module connector. Intermittent or poor connections in the inlineconnectors containing the High Speed GMLANS erial Data Bus circuits. Water intrusion in a control module :Model Year 2007 vehicles. The Terminator Resistor is open or :Model Year 2008 Sierra and Silverado vehicles. The Data Link Resistor is open or :Model Year 2009 and newer Sierra andSilverado vehicles. The Data Link Resistor 1 is open or :Model Year 2008 and newer Avalanche,Escalade, Tahoe, Yukon vehicles. The Data Link Resistor 1 is open or :Model Year 2008 and newer Hybrid RPO HP2vehicles. The Data Link Resistor 2 (RPO HP2) is open :The following cause only pertains to hybridRPO HP2 vehicles equipped with OnStar DeleteRPO UE0.

5 The High Speed GMLAN jumper harness loopconnector that plugs into the bottom rear of theinterior driver side junction block, is open orshorted from chafing on the IP ThisDon't Do ThisRepair or replace anybacked out or damagedtransmission connectorterminal(s) as NOT replace any controlmodule, wiring harness orcomponent until you havefirst isolated the cause of thecondition or followed thisprocedure in its that the transmissionconnector TPA is fullyseated (TPA is centered incheck window).Repair the High SpeedGMLAN Serial Data Buscircuits that are open,shorted to ground or havepoor the corrosion orwater intrusion condition inthe affected the TerminatorResistor that is open the Data LinkResistor 1 or Data LinkResistor 2 (RPO HP2vehicles only) that is open the junction blockjumper harness loopconnector wiring that is openor shorted. (RPO HP2 Vehicles equipped withOnStar DeleteRPO UE0 Only).Information for the Procedures toDiagnose and Repair the the Diagnostic System Check-Vehicleto begin your a thorough visual inspection of on the vehicle and vehicle build,some of the procedures may not be following procedure is the only oneapplicable to the Corvette and Wiring Harness at TransmissionCase Retaining Clip and Inspection ofthe 16-way Electrical Connector forBacked Out Terminals1.

6 Turn OFF the ignition and all Raise and support the vehicle. Refer to Lifting andJacking the Vehicle in No.: 08-07-30-021 GMarch, 2012 Page 3204330220433033. Locate the 16-way electrical connector on the rightside of the automatic transmission as Inspect for chafed, damaged, pinched, open orshorted wiring within the conduit of the harnesswhere it is secured at the transmission by a metalattachment clip as shown. Inspect any wiringharness where these metal attachment clips areused on the vehicle as needed. If the wiring is damaged, repair as to Power and Signal Distribution > WiringSystems and Power Management > DiagnosticInformation and Procedures in SI. Protect theconduit by covering any sharp edge with butyltape and the conduit and wiring harness withwoven polyester (PET) electrical tape. Securethe harness as the 16-way connector,inspectfor any backed out terminals (1) as seated terminals (2,3) are shown If a backed out terminal (1) is found, identifythe terminal(s) on therepair Look at the connector in order to identify thenumber of the cavity with the backed outterminal.

7 Refer to Wiring Systems and PowerManagement > Component Locator > MasterElectrical Component List in :For 2ML70 Only: Disconnect the 4 WALelectrical 4 March, 2012 Bulletin No.: 08-07-30-021G6. Use the following procedure to disconnect the16-way electrical Release and hold the slide lock on the wiringharness Rotate the connector lever and remove theconnector from the any backed out terminals (3) as seated terminals (1,2) are shown If a backed out terminal (3) is found, identifythe terminal(s) on therepair Look at the connector in order to identify thenumber of the cavity with the backed outterminal. Refer to Wiring Systems and PowerManagement > Component Locator > MasterElectrical Component List in Repair or replace the terminal(s) as necessaryusing the following Locate the terminal position assurance (TPA)as :The TPA cannot be removed from the connectorwhile there are terminals present in the connector Use a small flat blade tool to push the TPAuntil it bottoms No.

8 : 08-07-30-021 GMarch, 2012 Page See the release tool cross reference in theReference Guide of the J-38125 to ensurethat the correct release tool is used. Use theJ-38125-28 tool to release the terminals byinserting the tool into the terminal cavity While holding the removal tool in place,gentlypull the wire out of the back of :If the female terminal(s) must be replaced, it ispart number 22124472200. It is located in Yazaki traynumber 12 in the J-38125 Terminal Repair Repair or replace the terminal(s) as to the instructions in the If the wiring is damaged, repair as needed. Refer toPower and Signal Distribution > Wiring Systemsand Power Management > Diagnostic Informationand Procedures in Slide the new terminal(s) into the correct cavity atthe back of the connector until it locks in place. Thenew terminal(s) should be even with the otherterminal(s).11. Ensure that each terminal is locked in place bygentlypulling on the :The male terminal(s) cannot be repaired as theyare an integral part of the transmission controlmodule (TCM).

9 12. Inspect for bent or misaligned terminal(s) in thetransmission half of the electrical connector. If they are bent, use a suitable tool and applygentle pressure to straighten them. Indicate onthe repair order the terminal number thatwas bent. If they are damaged, replace the TCM. Refer toControl Solenoid Valve and TransmissionControl Module Assembly Replacement in Prior to installing the transmission connector,perform the following steps to ensure that the TPAlock is fully the TPA lock in the reassembledtransmission connector. Refer to the arrow in theillustration above, which points to a TPA lock. Thisone is in an unseated position. Using a small flatblade tool, push to seat the TPA until it bottomsout. Verify the TPA is fully If the TPA is off-center in the check window asshown, then it is only partially seated. Note thelarge gap at the arrow. Reseat the TPA lock andensure that it is fully 6 March, 2012 Bulletin No.

10 : 08-07-30-021G2089400 If the TPA lock is centered in the window asshown, then it is fully seated. The gaps shownby the arrows should be even on both :For 2ML70 Only: Connect the 4 WAL Connect the 16-way electrical connector to Lower the Clear any DTCs that may be present with a scantool and verify the proper operation of the of Fuse Block - I/P (Left Side)for Loose Connector X11. Turn OFF the ignition and all Disconnect the negative battery cable. Refer toBattery Disconnect Caution and Battery NegativeCable Disconnection and Connection in Remove the left side fuse block as Inspect connector X1 (1) on the back of the fuseblock for a loose connection. Secure the connectoras Install the left side fuse Connect the negative battery cable. Refer toBattery Negative Cable Disconnection andConnection in Clear any DTCs that may be present with a scantool and verify the proper operation of the IP Wiring Harness Near ParkBrake Pedal AssemblyThe above condition may cause one or more of thefollowing fuses to open: 60A - MBEC1 (#72) (Underhood) 30A - AMP (#40) (Underhood) 15A - RDO (#41) (Underhood) 10A - IPC (#46) (Underhood) 15A - AIR BAG BATT (#51) (Underhood) 10A - DSM (Left side of IP) Bulletin No.