Infiniti Q45 (FY33). Manual - part 81
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How to Perform Trouble Diagnoses for Quick
and Accurate Repair
INTRODUCTION
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The TCS has two electronic control units. One is called the TCS/
ABS control unit. The ABS system has an electronic control unit to
control major functions and for the ABS. The other is the throttle
control module (TAC module) which is used to control the throttle
opening. The control units accept input signals from sensors and
instantly drive actuators. It is essential that both kinds of signals are
proper and stable. Also there should be no such conventional prob-
lems as oil leaks in the TCS operating circuits. Nor should there be
lack of brake fluid or other problems with the brake system.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than continuously. Most intermittent problems are
caused by poor electric connections or faulty wiring. In this case,
careful checking of suspicious circuits may help prevent the
replacement of good parts.
A visual check only may not find the cause of the problems, so a
road test should be carried out.
Before undertaking actual checks, take just a few minutes to talk
with a customer who approaches with a TCS complaint. The cus-
tomer is a very good source of information on such problems;
especially intermittent ones. Through the talks with the customer,
find out what symptoms are present and under what conditions
they occur.
Start your diagnosis by looking for “conventional” problems first.
This is one of the best ways to troubleshoot brake problems on a
TCS controlled vehicle. Also check related Service Bulletins for
information.
It is strongly recommended that the TCS/ABS control unit be
checked for electrical problems first. Then check the TAC
module.
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TROUBLE DIAGNOSES
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