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CKP REF:
Crankshaft Reference.
CKP:
Crankshaft Position Sensor.
Closed Loop (C/L):
This is when a control system performs an
action (expecting a certain result), then
checks the results and corrects its actions
(if necessary) until the desired results are
achieved. Example: Fuel delivery. The PCM
operates a fuel injector in a way that should
deliver an optimum air/fuel mixture, as long
as everything in the fuel system is operating
as expected. In closed loop operation, the
PCM uses the oxygen sensor to check the
results (fuel delivery may be different than
expected because of variations in fuel pres-
sure or injector operation). If the oxygen sen-
sor indicates a rich condition, the PCM will
compensate by reducing fuel delivery until
the oxygen sensor signals an optimum air/
fuel mixture. Likewise, the PCM will com-
pensate for a lean condition by adding fuel
until the oxygen sensor once again signals
an optimum air/fuel mixture. Thus, closed
loop operation means the PCM can fine
tune control of a system to achieve an exact
result providing the PCM has a means to
check results (like an oxygen sensor).
CO:
Carbon Monoxide
Continuous Memory Codes:
See Pending Codes.
CPS:
Crankshaft Position Sensor. This sensor
sends a frequency signal to the PCM. It is
used to reference fuel injector operation and
synchronize spark plug firing on distributor-
less ignition systems (DIS).
CTS:
Coolant Temperature Sensor. IA thermistor
a sensor whose resistance decreases
with increases in temperature is threaded
into the engine block, contacting the engine
coolant. It sends a voltage signal to the PCM
indicating the temperature of the coolant.
The PCM uses this signal for control of fuel
delivery, spark advance, and EGR flow.
Data Link Connector (DLC):
The Data Link Connector (DLC) is a uni-
versal term for the interface port between
the vehicles on-board computer and a di-
agnostic tool. Vehicles with OBD II use a
16-pin connector located in the passenger
compartment.
Data Stream:
This is the actual data communications
broadcast from the vehicles PCM to the
data connector. The individual manufactur-
ers determine the number of data bytes a
specific engine will broadcast. The size of
the data stream is usually dependent on
the complexity of the engine, transmission,
ABS, and other systems supported by the
PCM. All manufacturers supply program
documents for each year, engine, and op-
tion combination that a particular PCM sup-
ports in all the manufacturers vehicles.
This information is used to design and build
aftermarket diagnostic equipment.
DEPS:
Digital Engine Position Sensor.
Detonation:
Uncontrolled ignition of the air/fuel mixture
in the cylinder. Also referred to as knock,
detonation indicates extreme cylinder pres-
sures or hotspots which are causing the
air/fuel mixture to detonate early. High cyl-
inder pressures may be caused by exces-
sive load (trailer towing, A/C operation, etc.)
or by excessive spark advance. High oc-
tane fuel has a higher resistance to uncon-
trolled ignition, and may be used to control
detonation when the PCM is unable to re-
tard timing sufficiently to prevent it from oc-
curring. NOTE: High octane fuel is not a
cure for the problem, only the symptom. If
your vehicle experiences long-term deto-
nation, check for other causes.