Hopper

For fun and giggles, I did an engine code check on my truck and wound up with a P0483 - "cooling fan rationality check function". Anyone have a clue what this means? My fan seems to turn just fine.

vzdude

I know its a lot, but here is the test for that code. Fairly simple after you read past all the mumbo jumbo! Hope it helps!



Symptom:
P0483-FAN SPEED
When Monitored and Set Condition:
P0483-FAN SPEED
When Monitored: While the engine is running.
Set Condition: The actual fan speed does not match the commanded fan speed.
POSSIBLE CAUSES
OTHER DTC’S
SIGNAL CIRCUIT SHORT TO SUPPLY CIRCUIT
SIGNAL WIRE OPEN FROM ECM TO FAN CLUTCH ASSEMBLY
INTERMITTENT CONDITION
SUPPLY CIRCUIT OPEN FROM ECM HARNESS CONNECTOR TO FAN CLUTCH HARNESS CONNECTOR
SIGNAL CIRCUIT SHORTED TO RETURN IN THE HARNESS
SIGNAL CIRCUIT SHORTED TO VOLTAGE
SIGNAL CIRCUIT IN ECM SHORTED TO GROUND INSIDE ECM
SIGNAL CIRCUIT SHORTED TO VOLTAGE IN THE ECM
(Y3) 5-VOLT SUPPLY IN ECM
TEST ACTION APPLICABILITY
1 With the DRBIIIt, read DTCs.
Is DTC P0480 present?
ENGINE- 5.9L
CUMMINS 24V
DIESEL
Yes ! Repair other DTC’s first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 2
2 Disconnect the
Measure the resistance between the signal circuit in the fan clutch assembly and the
battery supply circuit in the fan clutch assembly.
Is the resistance less than 10 Ohms?
ENGINE- 5.9L
CUMMINS 24V
DIESEL
Yes ! Replace the Fan clutch assembly.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 3
149
DRIVEABILITY - DIESELTEST ACTION APPLICABILITY
3 Disconnect the ECM harness connectors.
Check connectors - Clean/repair as necessary.
Measure the resistance of the signal circuit between the ECM harness connector and
the fan clutch assembly harness connector.
Is the resistance less than 10 Ohms?
ENGINE- 5.9L
CUMMINS 24V
DIESEL
Yes ! Go To 4
No ! Repair the open circuit from the ECM harness connector to the
Fan clutch harness connector.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
4 Measure the resistance of the supply circuit between the ECM harness connector and
the fan clutch assembly harness connector.
Is the resistance less than 10 Ohms?
ENGINE- 5.9L
CUMMINS 24V
DIESEL
Yes ! Go To 5
No ! Repair the open circuit from ECM harness connector to Fan
clutch connector.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
5 Measure the resistance between the signal circuit in the fan clutch assembly harness
connector and the return circuit in the fan clutch assembly harness connector.
Is the resistance less than 10 Ohms?
ENGINE- 5.9L
CUMMINS 24V
DIESEL
Yes ! Repair the shorted circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 6
6 Measure the voltage between the signal circuit in the fan clutch assembly harness
connector and battery negative.
Is the voltage greater than 1 volt?
ENGINE- 5.9L
CUMMINS 24V
DIESEL
Yes ! Repair the signal circuit shorted to voltage.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 7
7 Reconnect the ECM harness connectors.
Measure the resistance between the signal circuit in the fan clutch assembly harness
connector and battery negative.
Is the resistance less than 10 Ohms?
ENGINE- 5.9L
CUMMINS 24V
DIESEL
Yes ! Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No ! Go To 8

TEST ACTION APPLICABILITY

8 Reconnect the fan harness connector.
Turn the ignition on.
While back probing the fan connector measure the voltage between the fan speed
signal circuit in the fan clutch assembly harness connector and battery negative
while manually rotating the fan blade.
Did voltage go from less than 0.7 volts to 4.7 to 5.7 volts?
ENGINE- 5.9L
CUMMINS 24V
DIESEL
Yes

151

DRIVEABILITY - DIESEL

P0483-FAN SPEED —

Continued

Hopper

That is a boat-load. Thanks!

Road Traveler

Yeah I have gotten that code twice and both times my A/C dies!!