Computer Control Diagnostics
Although a "computer diagnosis" may sound serious, it is actually
a common practice used by automotive repair professionals to identify
problems inside today's computer-controlled cars. Computer control
diagnostics is often the most efficient and cost effective way for the
technicians at Murray's Auto Clinic in Silver Spring, MD to pinpoint
the cause of the problems you are experiencing with your car.
How Computer Control Diagnostics Work
Modern vehicles are equipped with an On-Board Diagnostics (OBD) that manages
the electronic control system. If a signal is recorded outside the normal
limits, or if an expected change in a signal is not recorded, a Diagnostic
Trouble Code (DTC) is stored in the OBD. If you are experiencing car trouble,
an automotive repair technician will connect a scanning tool to a diagnostic
link connector that is commonly located under the instrument panel on
the driver's side. This scan tool displays any DTCs stored by the
OBD. However, DTCs don't necessarily mean that a particular part or
component is bad bur rather indicate that the OBD has seen something it
didn't expect in a certain circuit. To pinpoint the problem, the technician
starts with the DTC and then performs additional tests ranging from mechanical
checks to in-depth electronic diagnosis.
Computer-Controlled Sensors and Modules
There are hundreds of different sensors and modules throughout your vehicle
that control almost every aspect of performance—and trouble with
just one of them can cause major car troubles. Here are some of the most
common sensors and electronic components that result in engine failure:
Crankshaft/Camshaft Position Sensor: This monitors the rotations of the engine and tells the computer exactly
when to trigger the fuel injectors or the ignition spark.
Electronic Control Module: The ECM controls spark timing, fuel delivery, and emission controls and
continuously monitors signals from sensors and input devices inside or
near the engine.
Fuel Injector: The ECM tells the fuel injector exactly when and how much fuel to inject
into the intake manifold to produce the needed amount of power.
Throttle Position Sensor: The TPS monitors the position of the accelerator pedal and throttle linkage
so the ECM can make accurate air/fuel mixture adjustments to optimize
performance and keep emissions low.
Speaking of emissions, one of the primary reasons for a failed emissions
test is a problem within the powertrain and emission control systems.
If your vehicle fails emissions, you will be given a Vehicle Emissions
Inspection Certificate and a Diagnostic Report which details the reasons
for the failure. You will automatically fail emissions testing if the
"Check Engine" light is on, so bring your car to Murray's
Auto Clinic before visiting VEIP. A diagnostics scan can reveal the cause
of the check engine light, which is most often caused by:
- Faulty oxygen sensor
- Faulty catalytic convertor
- Faulty mass airflow sensor
- Faulty spark plugs and/or spark plug wires