What really does cause induction contamination? - TAT - The ...

‘s a fact
problem solving
AUDA401114
AUDI A4 1.8T
2001
4 Cylinders
Customer Complaint
Vehicle was overheating.
Problem Summary
Scan tool code relating to coolant
temperature sensor was incorrect.
A new sensor had recently been
fitted.
Diagnostic Sequence
The system operation was
checked. The engine temperature
climbed beyond the required
levels for fans to cut in. There
was no action from the engine
fans on high or low speeds.
Tested the circuits and found the
signal was going to the control
module (as indicated in pic 3) but
still no fans.
The engine fan control module is
located on the fan shroud behind
the radiator on the inner top
passenger side.
Checked both fan motor circuits,
in and out, and had no continuity.
Found both fans internally open
circuited.
Fault Description
The fan assembly is located
between the engine and the
radiator.
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7
To access the fans and
remove the complete
assembly, the front end
has to be disassembled
including the front
bar and headlights so
that the radiator and
condenser section can
be pulled forward.
When the fans and
shroud assembly were
finally removed and
pulled apart they were
found to be totally
worn out. They were
so bad that both of
the commutators were
cut clean by the brush
spring arms.
As can be seen in these
images, the brushes
had broken up, allowing
the springs to contact
the segments and work
as the brush until they
cut right through to the
insulating bakelite.
Fault Solution
A new engine dual fan and
housing assembly was indentified
and supplied. The control box had
to be swapped over, the assembly
was refitted and the front end
reassembled. Functions tested
and all were OK.
Recommended Time
Labour time was 8.5 hours,
taking into account research time,
location of parts and actual time
spent fixing the problem.
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The Automotive Technician 17