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DTC › BMU5 BMU5 / 0277 4 variants

BDU pre-charge error

â–¶ How to fix

• If the battery system has been pre-charged to many times in a short while (3 times within 30s) the pre-charge resistor might be over heated. Wait for 2 minutes for the resistor to cool down • Check for DTC’s regarding the heater that might be the reason for pre-charge malfunction • Check VCB system for short circuits. Use DTC(0286 Current out of range) actions • Check the VCB main fuse located in the maintenance disconnector mounted in the battery pack(E83). Measure the resistance if open load change the fuse and also the BDU according to instruction in Multi. • Dismount the battery pack (E83) according to instruction in multi • Control the connections between the IBU and BDU that they are connected properly. • Change IBU mounted in battery pack(E83) according instruction in Multi • Change BDU mounted in battery pack(E83) according instruction in Multi NOTE! Replacing the IBU and BDU are considered as electrical work and shall only be performed by Scania certified personnel. Vehicle shall be made safe according to electrical work procedure.

What you'll see

No driver-visible symptom recorded.

System reaction

• The hybrid system will go to error state. It is not possible to activate the battery pack (E83). • VOR, the hybrid system will not work since the battery will not be engaged. The DCC will not receive VCB-power and the 24-volt system will drain the 24-volt batteries. • Amber warning lamp "24V batteries not charged" and "Hybrid System Fault" is shown in ICL

Diagnostic depth

Detection

Component fault nr. 10 from the IBU indicates the pre-charge time was above 1 second or Component fault nr. 11 from the IBU indicates that the energy content in the pre-charge resistor was above 385J.

Possible cause

• Pre-charge energy exceeded upper limit • Timeout error occurred during pre-charge • Heater is active during pre charge. • A short circuit make it impossible to charge the system. • BDU pre-charge circuit defective • BMU voltage measurement or pre-charge driver defective

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