Engine Cooling System: Diagnosis Saturn VUE I

Diagnostic Starting Point - Engine Cooling

Begin the system diagnosis with the diagnostic system check. Refer to Diagnostic System Check - Engine Cooling . The Diagnostic System Check will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the Class 2 serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Scan Tool Output Controls

Engine Control Module (ECM) L61 Scan Tool Output Controls

Powertrain Control Module (PCM) L66 Scan Tool Output Controls

Scan Tool Data List

Use the Scan Tool Data Display Values and Definitions Information in order to assist in diagnosing the HVAC Control Module problems. Compare the vehicles actual scan tool data with the typical data display value table information. Use the data information in order to aid in understanding the nature of the problem when the vehicle does not match with the typical data display values.

The scan tool data values were taken from a known good vehicle under the following conditions

1. The ignition switch is in the ON position.
2. The engine is running at idle.
3. The vehicle is in PARK.
4. The doors are closed.
5. The windows are closed.
6. The A/C is ON.
7. The ambient air temperatures are at 22-27°C (70-80°F).

Body Control Module (BCM) Scan Tool Data List

Engine Control Module (ECM) Scan Tool Data List - L61/2.2L

Powertrain Control Module (PCM) Scan Tool Data List - L66/3.5L

Diagnostic Trouble Code (DTC) List

Diagnostic Trouble Code (DTC) List

Scheme 5

Circuit Description

When the engine coolant is at the proper level in the surge tank, the low coolant level switch is closed. When in this condition, battery voltage is applied to the low coolant level signal circuit of the body control module (BCM). When coolant is below the proper level, the low coolant level switch opens. Because no voltage is applied to the low coolant level signal circuit, the BCM responds by sending a serial data message to the instrument panel cluster to turn on the low coolant level light. The BCM has an internal timer, which will not turn on the low coolant level light unless the coolant level is low for longer than 30 seconds. The timer avoids falsely turning on the light due to the movement of coolant within the surge tank.

Conditions for Running the DTC

1. Ignition switch in RUN or Crank position.
2. Low coolant warning light always ON with the ignition in Start.
3. BACKUP fuse in underhood fuse block is open.

Conditions for Setting the DTC

1. B0936 - The BCM detects a short to ground or an open on the coolant level signal circuit.
2. The condition exists for longer then 30 seconds.

Conditions for Clearing the DTC

1. The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. Use the scan tool Clear DTC Information function.

Diagnostic Aids

1. Check for poor connection at the BCM.
2. Check for poor connection at the low coolant level switch.
3. If the fault is suspected to be intermittent refer to «Testing for Intermittent Conditions and Poor Connections»(ref-188770-S18124834412005090200000) in Wiring Systems.

Conditions for Clearing the MIL/DTC

1. The ECM/PCM will turn the malfunction indicator lamp (MIL) OFF after 3 consecutive trips that the diagnostic has been run and passed.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using the scan tool.

1. Cooling fan inoperative - Refer to «Cooling Fan Inoperative (L61)»(ref-188798-S22491423032005090200000) «Cooling Fan Inoperative (L66)»(ref-188798-S27759120382005090200000) .
2. Engine cooling system overheated condition (thermostat, low engine coolant etc.) - Refer to «Engine Overheating»(ref-188798-S05571703362005090200000) .
3. Radiator or condenser air flow restricted
4. Air dam missing or loose
5. Overload due to trailer towing
6. ECT sensor leaking engine coolant into ECT sensor harness connector causing elevated temperatures
7. ECT sensor skewed

DTC P0217 Circuit

The engine control module (ECM) controls the low speed cooling fan operation by grounding the low speed fan relay control circuit with an internal solid state device called a driver. For high speed cooling fan operation, the ECM grounds the high and low speed relay control circuit at the same time. Battery positive voltage is supplied to the low and high speed fan relays. When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding a fan relay OFF, the voltage potential of the control circuit should be high, near battery voltage.

The ECM monitors the relay control circuits for the following conditions

1. Short to ground
2. Short to voltage
3. An open circuit

If the ECM detects an improper voltage level on the low or high speed driver circuits, then code P0480, P0481, P0691, P0692, P0693, P0694 or P1650 will set and the effected driver will be disabled.

1. The ignition voltage is between 8.0-18.0 volts
2. The engine speed is more than 40 RPM
3. The ECM driver transitions from ON to OFF or from OFF to ON

1. P0481 - The ECM detects an open circuit on the high speed cooling fan relay control circuit.
2. P0693 - The ECM detects a short to ground on the high speed cooling fan relay control circuit.
3. P0694 - The ECM detects a short to voltage on the high speed cooling fan relay control circuit.
4. P0480 - The ECM detects an open on the low speed cooling fan relay control circuit.
5. P0691 - The ECM detects a short to ground on the low speed cooling fan relay control circuit.
6. P0692 - The ECM detects a short to voltage on the low speed cooling fan relay control circuit.
7. The above condition is present for 5 seconds.
8. P1650 - The ECM detects a short to voltage on both the low and high speed cooling fan relay control circuit.
9. The above condition is present for 6 seconds.

Action Taken When the DTC Sets

1. The ECM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
2. The ECM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

1. The ECM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
2. The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. Use the scan tool Clear DTC Information function.

1. If the condition is not present, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-188770-S18124834412005090200000) in Wiring Systems.
2. Review the Freeze/Failure Records vehicle mileage since the diagnostic test failed. This may help determine how often the condition that caused the DTC to be set occurs.
3. Allow engine coolant temperature to drop below 80°C (176°F).
4. Set the A/C to the OFF position.
5. Once the ECM has enabled a low or high fan speed, that speed must run for a minimum of 20 seconds.

Battery positive voltage is supplied to the cooling fan 1 relay from the COOL FAN #1 fuse. The powertrain control module (PCM) controls the cooling fan 1 relay by grounding the low speed cooling fan relay control circuit via an internal solid state device called a driver.

Battery positive voltage is supplied to the cooling fan 2 relay and the cooling fan 3 relay from the COOL FAN #2 fuse. The powertrain control module (PCM) controls the relays by grounding the high speed cooling fan relay control circuit.

When the PCM is commanding a relay on, the voltage potential of the control circuit should be low, near 0 volts. When the PCM is commanding the control circuit to a relay, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the DTC will set.

The PCM will monitor the control circuit for the following

1. A short to ground
2. A short to voltage
3. An open circuit
4. An open relay coil
5. An internally shorted or excessively low resistance relay coil

When the PCM detects any of the above conditions, the DTC will set and the affected driver will be disabled.

1. The ignition is ON.
2. System voltage is between 8-18 volts.
3. The engine speed is more than 40 RPM
4. The relay control circuit is transitioned from OFF to ON or ON to OFF.

1. P0481 - The PCM detects an open circuit on the high speed cooling fan relay control circuit.
2. P0693 - The PCM detects a short to ground on the high speed cooling fan relay control circuit.
3. P0694 - The PCM detects a short to voltage on the high speed cooling fan relay control circuit.
4. P0480 - The PCM detects an open on the low speed cooling fan relay control circuit.
5. P0691 - The PCM detects a short to ground on the low speed cooling fan relay control circuit.
6. P0692 - The PCM detects a short to voltage on the low speed cooling fan relay control circuit.
7. The above condition is present for 5 seconds.
8. P1650 - The PCM detects a short to voltage on both the low and high speed cooling fan relay control circuit.
9. The above condition is present for 6 seconds.

1. The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
2. The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
3. The Service Vehicle Soon (SVS) light may be illuminated.

1. The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
2. The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
3. The DTC can be cleared by using the scan tool.

1. If the condition is not present, refer to «Testing for Intermittent Conditions and Poor Connections»(ref-188770-S18124834412005090200000) in Wiring Systems.
2. Review the Freeze/Failure Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Cooling System. Refer to «Checking Aftermarket Accessories»(ref-188770-S05143345352005090200000) in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Inspect the surge tank reservoir for the proper coolant level.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Low Engine Coolant Indicator Always On»(ref-188798-S35491202522005090200000)
2. «Cooling Fan Always On (L61)»(ref-188798-S20750413732005090200000) or «Cooling Fan Always On (L66)»(ref-188798-S18811381152005090200000)
3. «Cooling Fan Inoperative (L61)»(ref-188798-S22491423032005090200000) or «Cooling Fan Inoperative (L66)»(ref-188798-S27759120382005090200000)
4. «Engine Overheating»(ref-188798-S05571703362005090200000)
5. «Loss of Coolant»(ref-188798-S13738685092005090200000)
6. «Thermostat Diagnosis»(ref-188798-S16574484012005090200000)
7. «Coolant Heater Inoperative»(ref-188798-S11767989992005090200000)
8. «Engine Fails To Reach Normal Operating Temperature»(ref-188798-S29898998342005090200000)

Thermostat Diagnosis

Thermostat Diagnosis

Cooling System Leak Testing

Tools Required

1. SA9141E Cooling System Pressure Test Kit. See «Special Tools and Equipment»(ref-188798-S26468822222005090200000) .
2. J 42401 Radiator Cap / Surge Tank Test Adapter. See «Special Tools and Equipment»(ref-188798-S26468822222005090200000) .

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(ref-188798-S41848644222005090200000) .
3. Wash the pressure cap mating surface with water.
4. Use the SA9141E with J 42401 in order to apply pressure to the cooling system. See «Special Tools and Equipment»(ref-188798-S26468822222005090200000) . Wet the O-rings on the Surge Tank Pressure Test Adapter J42401-2 (insert) with water or clean coolant and insert into tank. Wet the rubber gasket of the cap adapter J42401-3 (cap) and install on surge tank.
5. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gage for any pressure loss.
6. Repair any leaks as required.