Diagnose
Status September 2003 (EvoBus-Service / AFT)
Page: 58 of 83
4.1.13
Coolant temperature
The coolant temperature is calculated every 40 ms. The calculated coolant temperature is a filtered
variable (low-pass filter). If the voltage of the coolant temperature sensor is above 4.97 V or below 0.35 V
for more than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected
and the fault code 1515 or 1516 is entered. In the "Engine starting" engine state (starting) the charge-air
temperature is used as a substitute value. In the other engine states the substitute value is 92 °C. If the
fault debouncing time has not yet expired, however the voltage value is outside the limits, then the last
coolant temperature calculated under valid conditions is retained. In the case of a fault, the measured
value is sent on the CAN as "Signal not available".
The characteristic curve of the coolant temperature sensor is stored in the engine data record.
Characteristic curve: Coolant temperature sensor
SEN - T engine: sensor code
Coolant temperature [°C] = f(Sensor voltage [V])
C
oolant temp
er
atu
re
Voltage
