MACS Monthly Newsletter - 2022 - JUN2

That could mislead the technician
into hours of trying to find a missed
problem. But almost surely the computer
likely is telling the technician
that coolant flow is still low, probably
because there still is air in the
system, and he should keep working
to bleed it.
If repeated bleeding doesn't indicate
any more air in the system,
and the code still won't clear, and
the engine was overheating, water
pump failure may indeed be responsible.
If the pump is noisy, that does
seem to point directly to the pump.
Electric water pump R&R is not
Figure 2: Right side of engine shows electric water pump in GM Active Cooling
system.
time, the repair and maintenance take on a special
importance. With the valves, sensors and computer
control, the system is capable of much more diagnostic
output than a conventional mechanical system.
The operation of the electric pump unsurprisingly,
is regulated closely.
So, if pump rpm is higher or lower than it should be
for the current applied, and if the coolant temperature
sensors read higher or lower than the computer
" believes " they should, it can use that information to
troubleshoot the system.
One of the computer's more useful diagnostics is
of coolant flow, which combined with coolant temperature
in the system, can indicate if the pump is
working efficiently. If the coolant level is sensed
as obviously low, and the diagnostic trouble code
P3075 is logged, that tells the technician that the
computer has detected low coolant flow. Okay, the
leak is repaired, the technician fills the system, and
clears the code. But it returns.
a tediously time-consuming job on
mainstream cars. The basic reason
for normally easy access for
the electric water pump is that it 's
mounted to the exterior of the engine.
To date, no one is integrating
the pump into an engine. And why
would it be? The pump is run by an
electric motor, so the typical reason
for building it onto or partly in
the engine, is to package to run off
a drive belt, a timing belt or chain, which doesn't
apply to an electric-motor-driven unit. Of course, a
packed powertrain compartment still could turn removal
of an externally mounted pump into a tough
job. So as a matter of general approach, before just
trying to remove the pump, take a close look to be
sure there's adequate clearance for a problem-free
R&R.
Even before you take the R&R step, in addition to
looking for trouble codes, don't forget diagnosis the
" old-fashioned way. " The computer can't tell you everything,
including many causes of overheating. You
should check to hear if the pump is making mechanical
noises and note if the wiring and terminals are
listed in a trouble code's diagnostic aids, such as a
poor or broken connection or a short.
You might also gain useful information by reviewing
what it takes to set a trouble code. A code only
June 2022
2
MACS Service Reports
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MACS Monthly Newsletter - 2022

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