Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1993 Volvo 850 L5-2.4L VIN 55 B5254SFACTORY OEM SERVICE PROCEDURE
Control Module Box Cooling Fan Not Running
CHECKING CONTROL MODULE BOX COOLING FAN
Conditions for Fault Tracing:
^ No DTCs present.
^ Fault is permanent.
Fault Sources:
^ Open-circuit in signal lead or supply lead.
^ Signal lead short-circuited to ground.
^ Faulty fan.
TESTING PROCEDURE
Fault Symptoms
If fan runs continuously, even when ignition is OFF:
- Check lead between Ignition Control Module (ICM) A28 and fan connector terminal 1 for short-circuit to ground.
If above symptom is not present:
- Proceed to: Functional Test of Fan.
Functional Test of Fan
^ Disconnect control module box air inlet pipe.
^ Activate Ignition System Diagnostic Test Mode 3, and check if control module box fan runs when engine cooling fan operates.
See: COMPUTERS AND CONTROL SYSTEMS / TESTING AND INSPECTION / OUTPUT DEVICE TEST - DIAGNOSTIC TEST MODE 3 / IGNITION SYSTEM.
If fan runs:
- Fault is intermittent.
If fan does not run:
- Proceed to: Checking Signal Lead.
Checking Signal Lead
^ Switch OFF ignition.
^ Disconnect fan.
^ Connect test box to Ignition system and check ground terminals.
^ Connect ohmmeter between #28 (ICM A28) on test box and tan connector terminal 1.
Instrument should indicate approx. 0 Ohms.
If reading is correct:
- Proceed to: Checking Fan Supply Lead.
If resistance is infinite:
- Check lead between ICM A28 and fan connector terminal 1 for open-circuit.
Checking Fan Supply Lead
^ Switch OFF ignition.
^ Disconnect fan.
^ Connect voltmeter between fan connector terminal 2 and ground.
Instrument should indicate battery voltage.
If reading is correct:
- Try with new fan.
If reading is incorrect:
- Check lead between fan connector terminal 2 and battery for open-circuit.
Conditions for Fault Tracing:
^ No DTCs present.
^ Fault is permanent.
Fault Sources:
^ Open-circuit in signal lead or supply lead.
^ Signal lead short-circuited to ground.
^ Faulty fan.
TESTING PROCEDURE
Fault Symptoms
If fan runs continuously, even when ignition is OFF:
- Check lead between Ignition Control Module (ICM) A28 and fan connector terminal 1 for short-circuit to ground.
If above symptom is not present:
- Proceed to: Functional Test of Fan.
Functional Test of Fan
^ Disconnect control module box air inlet pipe.
^ Activate Ignition System Diagnostic Test Mode 3, and check if control module box fan runs when engine cooling fan operates.
See: COMPUTERS AND CONTROL SYSTEMS / TESTING AND INSPECTION / OUTPUT DEVICE TEST - DIAGNOSTIC TEST MODE 3 / IGNITION SYSTEM.
If fan runs:
- Fault is intermittent.
If fan does not run:
- Proceed to: Checking Signal Lead.
Checking Signal Lead
^ Switch OFF ignition.
^ Disconnect fan.
^ Connect test box to Ignition system and check ground terminals.
^ Connect ohmmeter between #28 (ICM A28) on test box and tan connector terminal 1.
Instrument should indicate approx. 0 Ohms.
If reading is correct:
- Proceed to: Checking Fan Supply Lead.
If resistance is infinite:
- Check lead between ICM A28 and fan connector terminal 1 for open-circuit.
Checking Fan Supply Lead
^ Switch OFF ignition.
^ Disconnect fan.
^ Connect voltmeter between fan connector terminal 2 and ground.
Instrument should indicate battery voltage.
If reading is correct:
- Try with new fan.
If reading is incorrect:
- Check lead between fan connector terminal 2 and battery for open-circuit.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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