Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC U0599 (35), U1220 (34) (Battery Condition Monitor Module)
DTC U0599 : DC-DC Converter Serial Communication Receive Error
DTC U1220 : DC-DC Converter Serial Communication Transmit Error
NOTE: Before you troubleshoot, review the general troubleshooting information .
| DTC Description | Confirmed DTC | Pending DTC | Freeze Frame |
|---|---|---|---|
| U0599 DC-DC Converter Serial Communication Receive Error | |||
| U1220 DC-DC Converter Serial Communication Transmit Error |
DTC (Electric Powertrain)
- Problem verification
-1. Turn the vehicle to the ON mode.
-2. Clear the DTC with the HDS.
-3. Turn the vehicle to the OFF (LOCK) mode.
-4. Turn the vehicle to the ON mode, and wait for 10 seconds.
-5. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC Freeze Frame U0599 DC-DC Converter Serial Communication Receive Error U1220 DC-DC Converter Serial Communication Transmit Error Is DTC U0599 and/or U1220 indicated?
YES
Go to step 2.
NO
Intermittent failure. The system is OK at this time. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.
- DTC check
-1. Check for Pending or Confirmed DTCs with the HDS.
Traction motor control module
DTC Description Confirmed DTC Pending DTC Freeze Frame Generator motor control module
DTC Description Confirmed DTC Pending DTC Freeze Frame DTC (Electric Powertrain)
Are DTC U0599 or U1220, and any other DTCs indicated at the same time?
YES
Go to the indicated DTC's troubleshooting.
NO
Go to step 3.
- CAN gateway system DTCs check
-1. Check for CAN gateway system DTCs with the HDS.
DTC Description DTC DTC (CAN GATEWAY)
Are any DTCs indicated?
YES
Go to the CAN gateway system troubleshooting .
NO
Go to step 4.
- Open wire check (F-CAN A_H line)
-1. Remove the service plug and the IPU cover .
-2. Disconnect the following connectors.
Battery condition monitor module connector E (32P) PCU 33P connector -3. Measure the resistance between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Battery condition monitor module connector E (32P): disconnected PCU 33P connector: disconnected Test point 1 Battery condition monitor module connector E (32P) No. 9 Test point 2 PCU 33P connector No. 5 Is there 1.0 Ω or less?
YES
The F-CAN A_H wire is OK. Go to step 5.
NO
Repair an open in the F-CAN A_H wire between the PCU and the battery condition monitor module (E9).
- Open wire check (F-CAN A_L line)
-1. Measure the resistance between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Battery condition monitor module connector E (32P): disconnected PCU 33P connector: disconnected Test point 1 Battery condition monitor module connector E (32P) No. 8 Test point 2 PCU 33P connector No. 6 Is there 1.0 Ω or less?
YES
The F-CAN A_L wire is OK. Replace the PCU .
NO
Repair an open in the F-CAN A_L wire between the PCU and the battery condition monitor module (E8).
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.