VoltzsEngineeringSign in
Lesson 33In production35 min

Cooling fan circuits

Engine overheats but the fan works when directly powered. What controls the rest of the chain?

See the full curriculumAbout this module

What this lesson covers

CORE TEACHING Relay packs; fan modules; variable speed; coolant/A/C requests; PWM/LIN; ECU strategies. PRACTICAL DEMONSTRATIONS AND TESTS Scan fan request; actuator test; check heavy feed/ground; command signal; current draw. ADVANCED / SCAN TOOL LAYER Scope PWM/LIN command; compare ECT/A-C pressure inputs to requested fan speed. KEY DIAGNOSTIC QUESTIONS What input should request the fan? Does ECU request it? Does module receive command and deliver current? MUST-COVER CHECKPOINTS Map simple vs module-controlled architecture; prove heavy power and ground; verify switch/request; command output; measure load current; inspect signal/network where used.

What you will be able to do

Engine overheats but the fan works when directly powered. What controls the rest of the chain?

Where it sits in the programme

Builds on
Lesson 32: Fuel pump electrical diagnosis
Feeds into
Lesson 34: Wipers, park circuits and intelligent motors

More in Vehicle Circuits

  1. 27Electric windows from switch to motor
  2. 28Electric mirrors
  3. 29Central locking and keyless handles
  4. 30Exterior lighting and strange voltages
  5. 31Blower motor diagnosis
  6. 32Fuel pump electrical diagnosis
  7. 33Cooling fan circuits
  8. 34Wipers, park circuits and intelligent motors