Coolant heater overheated
Warning! The heater may be very hot. Working on the component may result in serious injury. Before starting any work, make sure that the heater has cooled off. •Disconnect H32-A and H32-B. Measure the resistance on the component between the pins H32-A3 and H32-A4. The resistance should be around 2.7kΩ at 20°C. If the resistance is below 660Ω, change the heater. •Leave H32-A and H32-B disconnected. Measure the resistance on the cable harness over E81-B3 and E81-B6. If the resistance is <OL, change the cable. •Reconnect H32-A, E81-B and E81-C. Leave H32-B disconnected. •Check the coolant level in the expansion tank for the battery cooling system. Run the pump in deaeration mode in SDP3 and make sure that the coolant level after the aeration is within the accepted levels. •Change the magnetic valve. Reconnect H32-B. Run “heater diagnostics program” in SDP3. •Drain the battery thermal management system from its coolant according to the instruction in PD2255172. Fill with new unused coolant. Run the “heater diagnostics program” in SDP3. •Change the BMU.
What you'll see
No driver-visible symptom recorded.
System reaction
• BMU request disable system and hybrid malfunction appears in the ICL • 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
The heater internal temperature sensor has detected too high temperature at three consecutive attempts to start the heater (with heater cool down between the attempts).
Bypass valve malfunction Heater temperature sensor feedback malfunction Clogging in cooling pipes Local air pockets in cooling system