{"id":19820,"date":"2026-10-29T05:00:17","date_gmt":"2026-10-29T09:00:17","guid":{"rendered":"https:\/\/gm-techlink.com\/?p=19820"},"modified":"2026-10-30T11:42:59","modified_gmt":"2026-10-30T15:42:59","slug":"tcsc-top-issues-this-week","status":"publish","type":"post","link":"https:\/\/gm-techlink.com\/?p=19820","title":{"rendered":"TCSC Top Issues This Week"},"content":{"rendered":"

The Techline Customer Support Center (TCSC) is available to help dealerships with diagnostic and programming issues related to Techline Connect (TLC) and the Service Programming System (SPS).<\/p>\n

TCSC has now released its latest tips to help technicians when using Techline Connect applications. (Fig. 1) Look for the latest information on TechLink each week.<\/p>\n

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\"\"Fig. 1<\/strong><\/p>\n

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To get the most out of Techline Connect, be sure to review the following items before making a call to TCSC.<\/p>\n

The following information covers current issues and trends facing dealerships as of October 29, 2026.<\/strong><\/p>\n

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WEEKLY ISSUES<\/strong><\/p>\n

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1. NEW<\/span> \u2013 2023 Hummer BSCM E4398 Errors<\/strong><\/p>\n

There is a known issue when programming the BSCM on MY2023 HUMMER models where error E4398 will appear in Techline Connect. If you are experiencing this issue, please contact Techline.<\/p>\n

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2. NEW<\/span> \u2013 2027 Vehicles: Brake System Control Module (BSCM) Loses Communication After Programming<\/strong><\/p>\n

Engineering is aware of an issue where the BSCM may go offline after a programming event on MY27 vehicles. This issue is currently under investigation. Meanwhile, the issue can be corrected with a 15-minute sleep cycle (key off, open\/close doors) to have the BSCM come back online.<\/p>\n

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3. SK4 (Extended Idle) Now Released for MY26+ T1 SUVs<\/strong><\/p>\n

The SK4 Extended Idle calibration is now available for 2026+ Tahoe, Suburban, Yukon and Escalade SUVs. Techline is now able to support the calibration add for these requests.<\/p>\n

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4. Service Power Steering Message with No DTCs Set on MY2025+ OPTIQ and LYRIQ<\/strong><\/p>\n

There is a known issue after programming the PSCM where a Service Power Steering\/Power Steering Unavailable – Drive With Care message will appear on the DIC without any DTCs set in the vehicle on 2025+ OPTIQ and LYRIQ models.<\/p>\n

This issue is being investigated by Engineering. Meanwhile, if you encounter this issue, please contact Techline for a VCI to correct it.<\/p>\n

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5. PACM PN 84169044 E4491 (B0, 85) in SPS2 on 2019 Trucks and SUVs<\/strong><\/p>\n

There is a known issue involving Park Assist Control Module part number<\/strong> 84169044<\/strong> where programming will fail in SPS2 (E4491 (B0, 85) on 2019 trucks and SUVs. This is a known supplier issue that is currently being investigated. There is currently no ETA at this time.<\/p>\n

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6. Super Cruise Inoperative or Unavailable, DTC B1599 SYM86 \u2013 #PIC6663<\/strong><\/p>\n

#PIC6663 (Document ID: 7220269) has been released to address issues with Super Cruise caused by DTC B1599 set in the K124 Image Processing Module on 2027 LYRIQ and T1 SUV models. Please refer to the PI for more information.<\/p>\n

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7. K73 OnStar\/Telematics Module E4393 Programming <\/strong><\/p>\n

Users may receive E4393 programming errors when programming K73 OnStar\/Telematics Module – Delta Programming<\/strong>. This error may occur on any vehicle.<\/p>\n

If you are experiencing this issue, please contact TCSC. Note: TCSC contact instructions are at the bottom of this document.<\/p>\n

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8. K299 Audio\/Video Interface Rear Module E4393 Programming Error on 2026 T1 SUVs<\/strong><\/p>\n

Users may receive E4393 programming errors when programming the K299 Audio Video Interface Rear Module \u2013 Rear Module Delta (Step 2)<\/strong>. If you encounter this error when programming, select the Do Not Use \u2013 Unsupported Function<\/strong> option for this module to successfully complete programming.<\/p>\n

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9. EPC Showing Incorrect Radio Hardware for 2025 Blazer EV with IVD Radio<\/strong><\/p>\n

Users report that the Electronic Parts Catalog (EPC) is directing to an incompatible part for the 2025 Blazer EV with the IVD radio.<\/p>\n

PN 85852385 is not compatible with the 2025 Blazer EV. Please order PN 85791702 instead.<\/p>\n

GM is working on correcting the EPC to show the correct hardware.<\/p>\n

Note: If you are unable to place an order for PN 85791702, please reach out to the dealership\u2019s Regional Operations Manager.<\/p>\n

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10. 2021 Tahoe, Suburban, Yukon, Escalade, Corvette, Envision, CT4, CT5 Unable to Complete SDAC \u2013 #PIT6507<\/strong><\/p>\n

There is currently a known issue affecting some 2021 model year vehicles where the SDAC (Serial Data Authentication Configuration) may fail. The radio, IPC, or Telematics (OnStar) modules may be the cause of these failures.<\/p>\n

DO NOT REPLACE THE MODULE.<\/strong> This is a known SPS issue and the current workaround is to reprogram the SDGM for the latest released calibrations and retry the programming event. If this does not resolve the issue, please refer to #PIT6507 for instructions on disconnecting the SDGM X3 connector and for more information on affected vehicles.<\/p>\n

Note: The X3 connector is very delicate. Please handle it with care.<\/p>\n

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11. UTQ (Content Theft), BCN (Retail Locking) and 6N6 (Rear Window Disable) Not Yet Available on 2026 Vehicles<\/strong><\/p>\n

Calibrations for RPOs UTQ, BCN and 6N6 are not yet available for model year 2026 vehicles but are planned to be released. However, there is not currently an ETA.<\/p>\n

Note: RPO SK4 calibrations are now available for T1 Trucks (Silverado, Sierra) and SUVs (Tahoe, Suburban, Yukon, Escalade).<\/p>\n

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COMMON ISSUES AND HELPFUL INFORMATION<\/strong><\/p>\n

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1. <\/strong>Bulletin<\/strong> #26-NA-156: Information on SPS Request Blocked by OnStar – Stolen Vehicle Key Programming Block<\/strong><\/p>\n

Dealers report when attempting to program in SPS2 that a \u201cSPS Request blocked by OnStar\u201d message is preventing the procedure from proceeding. Please see Bulletin #26-NA-156 (Document: 7135881) for instructions on how to resolve this issue.<\/p>\n

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2. ECM\/Radio\/IPC Part Missing from SPS2 Part Dropdown<\/strong><\/p>\n

When performing IPC Graphics programming, Radio USB, or ECM programming, you may be prompted in SPS2 to select \u201cService Hardware.\u201d<\/strong> However, this is misleading.<\/p>\n