Chevrolet U3636
Service agents must comply with all International, Federal, State, Provincial, and/or Local laws applicable to the activities it performs under this bulletin, including but not lim
Quick answer
For certain 2020–2023 Chevrolet Bolt EV and Bolt EUV vehicles in the US, U3636 Symptom 09 may be a false failure addressed by updated Hybrid Powertrain Control Module 2 (HPCM2) software under GM bulletin 23-NA-157. Verify vehicle applicability and diagnosis with a Chevrolet dealer or qualified service facility.
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 U3636 mean?
For certain 2020–2023 Chevrolet Bolt EV and Bolt EUV vehicles in the US, U3636 Symptom 09 may be a false failure addressed by updated Hybrid Powertrain Control Module 2 (HPCM2) software under GM bulletin 23-NA-157. Verify vehicle applicability and diagnosis with a Chevrolet dealer or qualified service facility.
2. Technical explanation
Verified evidence specifically concerns U3636 Symptom 09. GM bulletin 23-NA-157 states that updated HPCM2 software was developed to repair a U3636 09 false failure. The bulletin also states that, when U3636 09 is set and the battery pack has not previously been replaced, normal Service Information diagnostics should be followed. A later field-action communication, N242443490, instructs technicians to refer to 23-NA-157 when U3636 Symptom 09 is current or stored in history before proceeding with that field action. The supplied diagnostic title/meaning is truncated legal language from the service-bulletin procedure and does not establish a consumer-facing definition of U3636 beyond the evidence for Symptom 09.
3. What system is affected?
Hybrid Powertrain Control Module Control 2 (HPCM2) / hybrid-electric powertrain system, based on the verified service-bulletin evidence.
4. How serious is this code?
Not yet established by verified evidence. The supplied evidence does not assign a severity level.
5. Symptoms you may notice
- U3636 Symptom 09 may be current or stored in diagnostic history.
- Other driver-observable symptoms are not yet established by verified evidence.
6. Possible causes
- A U3636 Symptom 09 false failure may be addressed by updated HPCM2 software.
- If U3636 Symptom 09 is set and the battery pack has not previously been replaced, GM bulletin 23-NA-157 directs normal Service Information diagnostics.
- Other causes are not yet established by verified evidence.
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 Chevrolet dealer or qualified service facility.
- Provide the technician with DTC U3636 Symptom 09, if that is the reported code, and ask them to check GM bulletin 23-NA-157 and any applicable field action.
- Do not perform high-voltage battery or powertrain repairs yourself.
- Service agents must comply with applicable laws for dangerous-goods handling, deployment, preparation, classification, packaging, marking, labeling, and shipping, as stated in bulletin 23-NA-157.
10. Step-by-step troubleshooting
- Confirm whether the recorded code is specifically U3636 Symptom 09 and whether it is current or history.
- Verify whether the battery pack was previously replaced, as required by GM bulletin 23-NA-157 for the described diagnostic path.
- Have the service facility follow normal GM Service Information diagnostics when U3636 09 is set and the battery pack has not previously been replaced.
- Have the service facility determine whether updated HPCM2 software applies.
11. When to contact service
Contact a Chevrolet dealer or qualified service facility for diagnosis. The verified bulletin directs technicians to assess U3636 Symptom 09, battery-pack replacement history, normal Service Information diagnostics where applicable, and HPCM2 software applicability.
12. What the service center may check
- Check for U3636 Symptom 09 as a current or history DTC.
- Check battery-pack replacement history.
- Refer to GM bulletin 23-NA-157 before proceeding with field action N242443490 when U3636 Symptom 09 is current or history.
- Perform normal GM Service Information diagnostics when U3636 09 is set and the battery pack has not previously been replaced.
- Determine whether HPCM2 software requires updating.
13. Possible repair or resolution
- GM bulletin 23-NA-157 states that updated HPCM2 software was developed to repair a U3636 09 false failure.
- A final repair outcome for an individual vehicle is not yet established by verified evidence.
14. Affected vehicles
- Chevrolet Bolt EUV · 2020–2023 · US
- Chevrolet Bolt EV · 2020–2023 · US
15. Related TSBs / service bulletins
- GM/NHTSA manufacturer communication 23-NA-157, published September 8, 2023: addresses U3636 Symptom 09 false failures with updated HPCM2 software and provides direction based on battery-pack replacement history.
- GM/NHTSA manufacturer communication N242443490, published September 26, 2024: instructs technicians to refer to 23-NA-157 if U3636 Symptom 09 is current or history before continuing the field action.
16. Recall information
- No recall is established by the supplied verified evidence.
17. Official manufacturer information
Official NHTSA-hosted documents: 23-NA-157: https://static.nhtsa.gov/odi/tsbs/2023/MC-10243719-0001.pdf ; N242443490: https://static.nhtsa.gov/odi/tsbs/2024/MC-11008165-0001.pdf
19. Frequently asked questions
What does U3636 Symptom 09 mean on a Chevrolet Bolt?
The supplied verified evidence does not provide a complete plain-language definition. It establishes that GM bulletin 23-NA-157 addresses a possible U3636 09 false failure.
Can software resolve U3636 Symptom 09?
GM bulletin 23-NA-157 states that updated HPCM2 software was developed to repair a U3636 09 false failure.
Does U3636 Symptom 09 mean the battery pack must be replaced?
Not established by the supplied evidence. The bulletin requires technicians to verify whether the battery pack was previously replaced and directs normal Service Information diagnostics when U3636 09 is set and the pack has not previously been replaced.
Which vehicles are covered by the supplied applicability data?
US-market 2020–2023 Chevrolet Bolt EV and 2020–2023 Chevrolet Bolt EUV.