Scanning For Diagnostic Trouble Codes Video
How to Check for Trouble Codes
If you see a "check engine" or a "service engine soon" light in your instrument
cluster, your car has stored a diagnostic trouble
code. This means the computer system on your vehicle has detected a problem
within various systems it controls and monitors. Your vehicle has many different
sensors that monitor and control the various systems that keep
performance, mileage and
emissions at an optimum
level. If the trouble code light has been illuminated your vehicle enters into "limp
mode" this means it is running on a predetermined program that
causes poor mileage and increased
emissions. To find out what your vehicles computer sees wrong, you will need a simple
to use tool called an OBD11 trouble coder reader.
All 1996 and newer vehicles utilize a "D" style plug-in connector that connects
to the code reader. On most vehicles the connector is located in the driver's compartment,
usually under the dash on the drivers side. Once the code reader is plugged in you
can retrieve trouble codes the
engine computer has
stored in its memory. If your car is older than 1996, an OBD1 scanner is required
to read the codes. These OBD1 scanners will vary
depending on manufacturer. These diagnostic trouble codes are the same codes the
dealer and repair shops use to diagnose
and repair your vehicle. A code
reader can also be used to clear the trouble codes from the computers memory after
repairs have been made. An engine trouble code reader is an easy to use tool and
is a worthwhile investment for future repairs.
Trouble Code Retrieval Guide
Malfunction Indicator Lamp
The MIL has illuminated during driving this means there is a malfunction trouble
code stored in the vehicle's computer.
Locate Your Vehicle's Computer Connector
Locate your vehicle's computer connector (ALDL), most are on the
lower driver's side. In some vehicles you might need to look around a little, on
the passenger's side, and around the center console under a plastic cover. For more
information, check your
owner's manual.
Connecting to The Computer to Read Codes
Connect your code reader to the under dash connector. The code reader will automatically
turn on and prompt you to the next step for code retrieval. Once the code has been
identified look up the definition on the trouble code chart supplied with your code
reader. After repairs have been made, clear trouble codes and recheck system. After
codes have been cleared the computer system is ready for internal testing, this
means that while the vehicle is in operation the onboard computer is performing
tests on the control and monitoring systems. These tests are called "monitors" most
cars have between 4 and 8 monitor systems. The
computer goes through
its testing procedure in about 40 to 60 miles.
Common Problems
- OBD2 (OBDII) Scan Test
is Incomplete - The computer system or PCM (powertrain control module) that
controls your car is equipped with a basic operating program. This operating
program is designed to control your engine, transmission, emissions, safety
systems and more. If a scan has been performed by using a code scanner and a
"scan could not be completed" code is retrieved further troubleshooting is necessary.
Usually a trouble code P1000
or manufacturers equivalent. We have listed reasons for this condition.
-
Stuck
Engine Thermostat - If the engine thermostat has stuck open it forces the
engine coolant to stay at too low of a temperature causing the computer to stay
in open loop. This open loop creates a state of pre-programmed parameters were
no diagnostic tests can be preformed. (The PCM is constantly waiting for the
engine to heat up to operating temperature)
-
Shorted Oxygen Sensor
- Coolant Temperature
Sensor - The PCM relies on information from main sensors to operate properly;
if one of these sensors is severely shorted it can cause the PCM to stay in
open loop causing an incomplete systems check.
-
Shorted Fuel Injector
-If a fuel injector short circuits it can cause the engine not to run by shorting
the injector driver in the computer. This in turn can cause incomplete code
gathering that can result in a P1000 code.
After a car repair has been performed the
MIL (malfunction inductor lamp) indicator will illuminate because the technician
neglected to plug in a sensor. A blown
fuse can cause the MIL to illuminate. A shorted sensor can also cause the MIL
to illuminate.
Related Car Repair Information
