Cooling Fan Inoperative. Cadillac XLR 2007

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2007 🢒 XLR 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Cooling Fan Inoperative

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan speed control module. The cooling fan control module varies the voltage drop across the engine cooling fan motor in relation to the pulse width modulated signal. The cooling fan speed is affected by many different conditions and can be adjusted from 10 to 90 percent duty cycle (PWM). 90 percent is considered high fan speed. When multiple cooling speed requests are received the ECM uses the highest cooling fan speed of all the requests. During normal fan ON operation the control circuit voltage will be low and near battery voltage when the fan is OFF.

Diagnostic Aids

The ECM has the capability of providing command to the fan relays even while a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded on by the ECM.

Reference Information

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling Fan Description and Operation

Connector End View Reference

•	Engine Controls Connector End Views for the 4.4L engine and Engine Controls Connector End Views for the 4.6L engine

•	Engine Control Module Connector End Views for the 4.4L engine and Engine Control Module Connector End Views for the 4.6L engine

•	Electrical Center Identification Views

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

•	Cooling System Connector End Views

•	Scan Tool Data List for the 4.4L engine and Scan Tool Data List for the 4.6L engine

•	Scan Tool Data Definitions for the 4.4L engine and Scan Tool Data Definitions for the 4.6L engine

•	Scan Tool Output Controls for the 4.4L engine and Scan Tool Output Controls for the 4.6L engine

Circuit/System Verification

Ignition ON, command the cooling fan ON and OFF with a scan tool. Observe that the cooling fan turns ON and OFF with each command.

Circuit/System Testing

Ignition OFF, disconnect the cooling fan control module.
Connect a jumper wire between the fan ground circuit terminal and ground.
Connect a 30A fused jumper wire between the positive terminal at the battery and the fan voltage supply circuit terminal and verify fan activation.

⇒	If the fan does not activate, test the fan voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, test the fan ground circuit for an open/high resistance. If the fan did not activate and the circuits test normal, replace the fan.

Ignition ON, connect the 30A fused jumper wire between the fan control module voltage supply circuit terminal and the fan voltage supply circuit terminal and verify fan activation.

⇒	If the fan does not activate, test the fan control module voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.