SPN 647 - FMI 4 (Fault Code 245)
Sunday, July 15, 2018
Fault Codes CUMMINS GTA38 K38 K50 QSK38 QSK50/60 CM850,
Fault Codes CUMMINS Signature ISX QSX15 CM570
SPN647 FMI4
Fan Control Circuit - Voltage Below Normal or Shorted to Low Source
CODES:
Fault Code: 245
PID(P), SID(S): S33
SPN: 647
FMI: 4/4
Lamp: Amber
REASON: Low signal voltage detected at the fan control circuit when commanded ON.
EFFECT: The fan can stay on continuously or not run at all.
Circuit Description:
The fan control circuit is a device used by the engine to control the fan operation. When the engine control module (ECM) energizes the fan control circuit, the engine fan is engaged.
The fan control circuit utilizes a pulse width modulated (PWM) signal. A PWM signal is a pulsed voltage signal between 0-VDC and system voltage. The frequency of the pulsed voltage signal is dependent on the application requirement.
There are two types of fans supported by the fan control circuit; variable speed and ON/OFF. The recommended Cummins® electronic service tool or equivalent can be used to determine which fan type is currently set up for use. The fan control circuit varies by original equipment manufacturer (OEM). Certain OEMs can use a solenoid return that is wired to the ECM or can use a return that goes to the engine block or chassis ground.
Component Location:
The control solenoid location varies by OEM. Refer to the appropriate OEM service manual to determine the location.
Conditions for Running the Diagnostics:
This diagnostic runs when the keyswitch is in the ON position and when the pulse width modulated (PWM) device is getting energized or de-energized. In some cases, the diagnostics can also run at some fixed intervals.
Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the fan control circuit pulse width modulated (PWM) signal was not at system voltage when the pulse width modulated (PWM) signal was commanded ON.
Action Taken When the Fault Code is Active:
• The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
-Fan operation will be disabled.
Conditions for Clearing the Fault Code:
• To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
• The fault code status displayed by the recommended Cummins® electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
• The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
• The "Reset All Faults" command in the recommended Cummins® electronic service tool or equivalent can be used to clear active and inactive faults.
Shop Talk:
The fan control logic can be adjusted with the recommended Cummins® electronic service tool or equivalent. There are two choices: 12 or 24 volts ON, or 0 volts ON. For proper fan operation, the fan control logic setup with the recommended Cummins® electronic service tool or equivalent must match the hardware configuration on the vehicle.
This fault code is logged when the ECM commands 12 or 24-VDC to the fan control solenoid, but the voltage on the fan control signal circuit is less than 12 or 24-VDC. The low voltage on the signal circuit usually indicates a short circuit to ground in the harness or solenoid.
If Fault Code 245 is still active after completing the following troubleshooting steps, consult the OEM service manual for procedures to check the fan control circuit for a short circuit to ground.
Read More:
SPN 632 - FMI 3 (Fault Code 255)
SPN 632 - FMI 4 (Fault Code 254)
Blog.Teknisi
Fan Control Circuit - Voltage Below Normal or Shorted to Low Source
 |
| Fan Control Circuit |
CODES:
Fault Code: 245
PID(P), SID(S): S33
SPN: 647
FMI: 4/4
Lamp: Amber
REASON: Low signal voltage detected at the fan control circuit when commanded ON.
EFFECT: The fan can stay on continuously or not run at all.
Circuit Description:
The fan control circuit is a device used by the engine to control the fan operation. When the engine control module (ECM) energizes the fan control circuit, the engine fan is engaged.
The fan control circuit utilizes a pulse width modulated (PWM) signal. A PWM signal is a pulsed voltage signal between 0-VDC and system voltage. The frequency of the pulsed voltage signal is dependent on the application requirement.
There are two types of fans supported by the fan control circuit; variable speed and ON/OFF. The recommended Cummins® electronic service tool or equivalent can be used to determine which fan type is currently set up for use. The fan control circuit varies by original equipment manufacturer (OEM). Certain OEMs can use a solenoid return that is wired to the ECM or can use a return that goes to the engine block or chassis ground.
Component Location:
The control solenoid location varies by OEM. Refer to the appropriate OEM service manual to determine the location.
Conditions for Running the Diagnostics:
This diagnostic runs when the keyswitch is in the ON position and when the pulse width modulated (PWM) device is getting energized or de-energized. In some cases, the diagnostics can also run at some fixed intervals.
Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the fan control circuit pulse width modulated (PWM) signal was not at system voltage when the pulse width modulated (PWM) signal was commanded ON.
Action Taken When the Fault Code is Active:
• The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
-Fan operation will be disabled.
Conditions for Clearing the Fault Code:
• To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
• The fault code status displayed by the recommended Cummins® electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
• The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
• The "Reset All Faults" command in the recommended Cummins® electronic service tool or equivalent can be used to clear active and inactive faults.
Shop Talk:
The fan control logic can be adjusted with the recommended Cummins® electronic service tool or equivalent. There are two choices: 12 or 24 volts ON, or 0 volts ON. For proper fan operation, the fan control logic setup with the recommended Cummins® electronic service tool or equivalent must match the hardware configuration on the vehicle.
This fault code is logged when the ECM commands 12 or 24-VDC to the fan control solenoid, but the voltage on the fan control signal circuit is less than 12 or 24-VDC. The low voltage on the signal circuit usually indicates a short circuit to ground in the harness or solenoid.
If Fault Code 245 is still active after completing the following troubleshooting steps, consult the OEM service manual for procedures to check the fan control circuit for a short circuit to ground.
Read More:
SPN 632 - FMI 3 (Fault Code 255)
SPN 632 - FMI 4 (Fault Code 254)
Blog.Teknisi
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