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Cadillac U35B5

voltage battery surge tank and document via photo. 3. Observe and record the Battery Energy Control Module parameter(s); K16 – Battery Energy Control Module -> Data Display -> High

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceService evaluation is appropriate because the official bulletin places U35B5 within a high-voltage battery diagnostic procedure requiring trained personnel. Urgency is not otherwise established by the supplied evidence.
Confidence95%

Quick answer

U35B5 is documented in Cadillac bulletin 23-NA-151 for certain U.S.-market Cadillac LYRIQ and VISTIQ vehicles. The supplied evidence associates it with inspection/documentation of high-voltage battery surge-tank coolant level and Battery Energy Control Module high-voltage isolation data. Its exact fault definition, driving status, charging status, and severity are not yet established by verified evidence.

This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.

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1. What does U35B5 mean?

U35B5 is documented in Cadillac bulletin 23-NA-151 for certain U.S.-market Cadillac LYRIQ and VISTIQ vehicles. The supplied evidence associates it with inspection/documentation of high-voltage battery surge-tank coolant level and Battery Energy Control Module high-voltage isolation data. Its exact fault definition, driving status, charging status, and severity are not yet established by verified evidence.

2. Technical explanation

The supplied canonical text is a truncated service-procedure fragment rather than a verified plain-language DTC definition. Bulletin 23-NA-151 includes U35B5 in diagnostic screening. Earlier versions instruct trained technicians to visually inspect and photograph coolant level in the high-voltage battery surge tank and to record Battery Energy Control Module high-voltage isolation data. Later revisions list U35B5 among current DTCs to verify; the April 8, 2025 revision also notes updated information involving pack damage and SPS data-dump capture.

3. What system is affected?

High-voltage battery system, including the high-voltage battery surge tank and Battery Energy Control Module high-voltage isolation data, as identified in the bulletin procedure.

4. How serious is this code?

Unknown. Not yet established by verified evidence.

5. Symptoms you may notice

  • No driver-visible symptoms are established by the supplied verified evidence.
  • The bulletin procedure calls for documentation of the customer concern, but the supplied evidence does not state a specific symptom for U35B5.

6. Possible causes

  • Not yet established by verified evidence. The supplied bulletin evidence provides diagnostic inspection and data-collection steps, not a verified root cause for U35B5.

7. Can I still drive the vehicle?

Not yet established by verified evidence.

8. Can I charge the vehicle?

Not yet established by verified evidence.

9. What you can safely do

  • Arrange diagnosis by a Cadillac/GM service facility or a technician with required high-voltage training.
  • Record the warning messages, charging behavior, and operating conditions present when the code or concern occurred.
  • Do not attempt high-voltage battery, coolant-system, or isolation-resistance repairs yourself.

10. Step-by-step troubleshooting

  1. A trained technician should verify whether U35B5 is current or history, as specified by the applicable revision of bulletin 23-NA-151.
  2. The bulletin procedure includes visually inspecting and photographing coolant level in the high-voltage battery surge tank.
  3. The procedure includes observing and recording Battery Energy Control Module high-voltage isolation data.
  4. The April 2025 bulletin revision mentions SPS data-dump capture and pack-damage-related updates.

11. When to contact service

Service evaluation is appropriate because the official bulletin places U35B5 within a high-voltage battery diagnostic procedure requiring trained personnel. Urgency is not otherwise established by the supplied evidence.

12. What the service center may check

  • Verify U35B5 status as current or history, per the applicable bulletin revision.
  • Document the customer concern.
  • Inspect and photograph coolant level in the high-voltage battery surge tank.
  • Record Battery Energy Control Module high-voltage isolation data.
  • Perform SPS data-dump capture where directed by the applicable April 2025 bulletin revision.

13. Possible repair or resolution

  • No specific repair or final resolution for U35B5 is established by the supplied verified evidence.
  • Follow the applicable Cadillac/GM diagnostic procedure in bulletin 23-NA-151.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Cadillac/GM bulletin 23-NA-151, NHTSA manufacturer communication MC-10245234, published October 19, 2023: includes U35B5 in the procedure and directs inspection/photo documentation of high-voltage battery surge-tank coolant level plus recording of Battery Energy Control Module high-voltage isolation data.
  • Cadillac/GM bulletin 23-NA-151, NHTSA manufacturer communication MC-11002022, published June 5, 2024: directs verification of U35B5 as current or history and inspection/documentation of high-voltage battery surge-tank coolant level.
  • Cadillac/GM bulletin 23-NA-151, NHTSA manufacturer communications MC-11011944 and MC-11012693, published November 20, 2024 and December 11, 2024: list U35B5 among DTCs to verify as current.
  • Cadillac/GM bulletin 23-NA-151, NHTSA manufacturer communication MC-11017886, published April 9, 2025: revision dated April 8, 2025 removes U35B5 from stated steps 2 and 7 and adds references to pack damage and SPS data-dump capture.

16. Recall information

  • No recall is established by the supplied verified evidence.

17. Official manufacturer information

Official NHTSA-hosted manufacturer communications: https://static.nhtsa.gov/odi/tsbs/2025/MC-11017886-0001.pdf ; https://static.nhtsa.gov/odi/tsbs/2025/MC-11012693-0001.pdf ; https://static.nhtsa.gov/odi/tsbs/2024/MC-11011944-0001.pdf ; https://static.nhtsa.gov/odi/tsbs/2024/MC-11002022-0001.pdf ; https://static.nhtsa.gov/odi/tsbs/2023/MC-10245234-0001.pdf

19. Frequently asked questions

What does U35B5 mean?

A complete plain-language definition is not established by the supplied verified evidence. The supplied canonical meaning is a truncated service-procedure fragment. Official bulletin evidence associates U35B5 with high-voltage battery diagnostic screening.

Which vehicles are covered by the supplied evidence?

The supplied applicability data lists U.S.-market Cadillac LYRIQ model years 2023–2026 and Cadillac VISTIQ model years 2023–2026. Exact applicability should be confirmed against the current bulletin and vehicle VIN.

Can I drive or charge with U35B5?

Not yet established by verified evidence.

Is U35B5 covered by a recall?

No recall is established by the supplied verified evidence.

20. Sources & verification

Verified
Cadillac U35B5: voltage battery surge tank and document via photo. 3.… | EV Diagnostics