Cooling Fan Always On (LPL or LPV)
Diagnostic Instructions
Diagnostic Fault Information
Cooling Fan Low Speed Relay
Circuit
|
Short to Ground
|
High Resistance
|
Open
|
Short to Voltage
|
Signal Performance
|
Relay Coil Ignition
|
P0691
|
P0691
|
P0691
|
-
|
-
|
Relay Switch B+
|
1
|
1
|
1
|
-
|
-
|
Relay Coil Control
|
P0691
|
P0691
|
P0691
|
P0692
|
-
|
Relay Output Control
|
1
|
1
|
1
|
2
|
-
|
1. Fan Inoperative Without a DTC.
2. Fan Always ON Without a DTC.
|
|
| |
Cooling Fan Medium Speed Relay (w/AC), Cooling Fan High Speed
(w/o AC)
Circuit
|
Short to Ground
|
High Resistance
|
Open
|
Short to Voltage
|
Signal Performance
|
Relay Coil Ignition
|
P0693
|
P0693
|
P0693
|
-
|
-
|
Relay Switch B+
|
1
|
1
|
1
|
-
|
-
|
Relay Coil Control
|
P0693
|
P0693
|
P0693
|
P0694
|
-
|
Relay Output Control
|
1
|
1
|
1
|
2
|
-
|
1. Fan Inoperative Without a DTC.
2. Fan Always ON Without a DTC.
|
|
| |
Cooling Fan High Speed Relay (w/AC)
Circuit
|
Short to Ground
|
High Resistance
|
Open
|
Short to Voltage
|
Signal Performance
|
Relay Coil Ignition
|
P0695
|
P0695
|
P0695
|
-
|
-
|
Relay Switch B+
|
1
|
1
|
1
|
-
|
-
|
Relay Coil Control
|
P0695
|
P0695
|
P0695
|
P0696
|
-
|
Relay Output Control
|
1
|
1
|
1
|
2
|
-
|
1. Fan Inoperative Without a DTC.
2. Fan Always ON Without a DTC.
|
|
| |
Circuit/System Description
The engine control module (ECM) commands the fans ON in either
high speed, medium speed, or low speed, depending on cooling
requirements.
Low Speed
In low speed operation, the ECM applies ground to the coil side of
the cooling fan low speed relay with the cooling fan relay 1
control circuit. This energizes the relay coil. The low speed
cooling fan relay supply power to the cooling fan motor through an
internal fan resistor.
Medium Speed
In medium speed operation, the ECM commands the medium speed fan
relay on. This energizes the relay coil. The medium speed cooling
fan relay supply power to the cooling fan motor through an internal
fan resistor. The cooling fan is connected to a dedicated ground,
and operates at medium speed.
High Speed
In high speed operation, the ECM applies a ground to the coil side
of all the high speed cooling fan relay. When energized, the high
speed relays apply voltage directly to the cooling fan through the
switch side of the relay.
Reference Information
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Cooling System Description and Operation
Electrical Information Reference
Circuit/System Verification
Cooling Fan Always ON with AC
| 1. |
Verify that DTC P0116, P0117
or P0118 is not present. |
| 2. |
Command the Cooling Fan Relay
1 ON and OFF with a scan tool. The cooling fan motor should turn ON
at low speed and OFF when changing between the commanded
states. |
| ⇒ |
If the cooling fan motor does not operate
correctly, refer to Cooling Fan Always ON with AC. |
| 3. |
Command the Cooling Fan Relay
2 ON and OFF with a scan tool. The cooling fan motor should turn ON
at medium speed and OFF when changing between the commanded
states. |
| ⇒ |
If the cooling fan motor does not operate
correctly, refer to Cooling Fan Always ON with AC. |
| 4. |
Command the Cooling Fan Relay
3 ON and OFF with a scan tool. The cooling fan motor should turn ON
at high speed and OFF when changing between the commanded
states. |
| ⇒ |
If the cooling fan motor does not operate
correctly, refer to Cooling Fan Always ON with AC. |
Cooling Fan Always ON without AC
| 1. |
Verify that DTC P0116, P0117
or P0118 is not present. |
| 2. |
Command the Cooling Fan Relay
1 ON and OFF with a scan tool. The cooling fan motor should turn ON
at low speed and OFF when changing between the commanded
states. |
| ⇒ |
If the cooling fan motor does not operate
correctly, refer to Cooling Fan Always ON without AC. |
| 3. |
Command the Cooling Fan Relay
2 ON and OFF with a scan tool. The cooling fan motor should turn ON
at medium speed and OFF when changing between the commanded
states. |
| ⇒ |
If the cooling fan motor does not operate
correctly, refer to Cooling Fan Always ON without AC. |
Circuit/System Testing
Cooling Fan Always ON with AC
| 1. |
Ignition OFF, disconnect the
relays listed below: |
| |
• |
KR20B Cooling Fan Medium Speed
2 Relay |
| |
• |
KR20C Cooling Fan Low Speed
Relay |
| |
• |
KR20D Cooling Fan High Speed
Relay |
| 2. |
Ignition ON, verify the G10
Cooling Fan Motor is not activated. |
| ⇒ |
If the G10 Cooling Fan Motor is activated, test
the control circuits listed below for a short to voltage. If the
circuit tests normal, replace the X50A Fuse Block - Underhood. |
| |
• |
G10 Cooling Fan Motor low
speed control terminal 2 |
| |
• |
G10 Cooling Fan Motor medium
speed control terminal 3 |
| |
• |
G10 Cooling Fan Motor high
speed control terminal 4 |
| 3. |
Ignition OFF, disconnect the
harness connector X1 at the K20 Engine Control Module. Test for
infinite resistance between the relay coil control circuit
terminals listed below and ground. |
| |
• |
KR20B Cooling Fan Medium Speed
2 Relay control terminal 85 |
| |
• |
KR20C Cooling Fan Low Speed
Relay control terminal 85 |
| |
• |
KR20D Cooling Fan High Speed
Relay control terminal 85 |
| ⇒ |
If less than the specified value, test the relay
coil control circuit for a short to ground. If the circuit tests
normal, replace the X50A Fuse Block - Underhood. |
| 4. |
Connect the KR20B Cooling Fan
Medium Speed 2 Relay. |
| 5. |
Ignition ON, verify the G10
Cooling Fan Motor is not activated. |
| ⇒ |
If the G10 Cooling Fan Motor is activated, test or
replace the KR20B Cooling Fan Medium Speed 2 Relay. |
| 6. |
Ignition OFF, connect the
KR20C Cooling Fan Low Speed Relay. |
| 7. |
Ignition ON, verify the G10
Cooling Fan Motor is not activated. |
| ⇒ |
If the G10 Cooling Fan Motor is activated, test or
replace the KR20C Cooling Fan Low Speed Relay. |
| 8. |
Ignition OFF, connect the
KR20D Cooling Fan High Speed Relay. |
| 9. |
Ignition ON, verify the G10
Cooling Fan Motor is not activated. |
| ⇒ |
If the G10 Cooling Fan Motor is activated, test or
replace the KR20D Cooling Fan High Speed Relay. |
| 10. |
If all circuit tests normal,
replace the K20 Engine Control Module. |
Cooling Fan Always ON without AC
| 1. |
Ignition OFF, disconnect the
relays listed below: |
| |
• |
KR20C Cooling Fan Low Speed
Relay |
| |
• |
KR20D Cooling Fan High Speed
Relay |
| 2. |
Ignition ON, verify the G10
Cooling Fan Motor is not activated. |
| ⇒ |
If the G10 Cooling Fan Motor is activated, test
the control circuits listed below for a short to voltage. If the
circuit tests normal, replace the X50A Fuse Block - Underhood. |
| |
• |
G10 Cooling Fan Motor low
speed control terminal 2 |
| |
• |
G10 Cooling Fan Motor high
speed control terminal 4 |
| 3. |
Ignition OFF, disconnect the
harness connector X1 at the K20 Engine Control Module. Test for
infinite resistance between the relay coil control circuit
terminals listed below and ground. |
| |
• |
KR20C Cooling Fan Low Speed
Relay control terminal 85 |
| |
• |
KR20D Cooling Fan High Speed
Relay control terminal 85 |
| ⇒ |
If less than the specified value, test the relay
coil control circuit for a short to ground. If the circuit tests
normal, replace the X50A Fuse Block - Underhood. |
| 4. |
Ignition OFF, connect the
KR20C Cooling Fan Low Speed Relay. |
| 5. |
Ignition ON, verify the G10
Cooling Fan Motor is not activated. |
| ⇒ |
If the G10 Cooling Fan Motor is activated, test or
replace the KR20C Cooling Fan Low Speed Relay. |
| 6. |
Ignition OFF, connect the
KR20D Cooling Fan High Speed Relay. |
| 7. |
Ignition ON, verify the G10
Cooling Fan Motor is not activated. |
| ⇒ |
If the G10 Cooling Fan Motor is activated, test or
replace the KR20D Cooling Fan High Speed Relay. |
| 8. |
If all circuit tests normal,
replace the K20 Engine Control Module. |
Component Testing
Dynamic Test
| 1. |
Ignition OFF, disconnect the
applicable relay. |
| 2. |
Test for 70-110 Ω
between terminals 85 and 86 of the relay. |
| ⇒ |
If the resistance is not within the specified
range, replace the relay. |
| 3. |
Test for infinite resistance
between the following terminals: |
| ⇒ |
If not the specified value, replace the relay. |
| 4. |
Install a 20 A fused jumper
wire between relay terminal 85 and 12 V. Install a jumper wire
between relay terminal 86 and ground. Test for less than 2 Ω
between terminals 30 and 87. |
| ⇒ |
If greater than the specified value, replace the
relay. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|
