Emission Control Systems; On-Board Diagnostics - Chrysler 1998 Viper RT/10 Owner's Manual

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EMISSION CONTROL SYSTEMS 2 5 - 1
EMISSION CONTROL SYSTEMS
C O N T E N T S
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EVAPORATIVE EMISSION CONTROLS . . . . . . . . 10 ON-BOARD DIAGNOSTICS 1
ON-BOARD DIAGNOSTICS
INDEI
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G E N E R A L I N F O R M A T I O N
S Y S T E M D E S C R I P T I O N 1
D E S C R I P T I O N A N D O P E R A T I O N
C I R C U I T A C T U A T I O N T E S T M O D E . . . . . . . . . . . 2
C O M P O N E N T M O N I T O R S
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D I A G N O S T I C T R O U B L E C O D E S 2
H I G H A N D L O W L I M I T S 9
G E N E R A L
I N F O R M A T I O N
SYSTEM DESCRIPTION
The Powertrain Control Module (PCM) monitors
many different circuits i n the fuel injection, ignition,
emission and engine systems. I f the P C M senses a
problem w i t h a monitored circuit often enough to
indicate an actual problem, i t stores a Diagnostic
Trouble Code (DTC) i n the PCM's memory. I f the
code applies to a non-emissions related component or
system, and the problem is repaired or ceases to
exist, the P C M cancels the code after 40 warrriup
cycles. Diagnostic trouble codes t h a t affect vehicle
emissions illuminate the Malfunction Indicator Lamp
( M I L ) . Refer to Malfunction Indicator Lamp i n this
section.
Certain criteria must be met before the P C M
stores a DTC i n memory. The criteria may be a spe-
cific range of engine RPM, engine temperature,
and/or i n p u t voltage to the P C M .
The P C M might not store a DTC for a monitored
circuit even though a malfunction has occurred. This
may happen because one of the DTC criteria for the
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L O A D V A L U E . . . . 9
M A L F U N C T I O N I N D I C A T O R L A M P (MIL) 2
M O N I T O R E D S Y S T E M S . 6
N O N - M O N I T O R E D C I R C U I T S . . . . . . . . . . . . . . .
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STATE D I S P L A Y T E S T M O D E 2
T R I P D E F I N I T I O N 8
circuit has not been met. F o r e x a m p l e , assume the
diagnostic trouble code criteria requires the PCM to
monitor the circuit only when the engine operates
between 750 and 2000 RPM. Suppose the sensor's
output circuit shorts to ground when engine operates
above 2400 R P M (resulting i n 0 volt i n p u t to the
PCM). Because the condition happens at an engine
speed above the m a x i m u m threshold (2000 rpm), the
P C M w i l l not store a DTC.
There are several operating conditions for which
the P C M monitors and sets DTC's. Refer to Moni-
tored Systems, Components, and Non-Monitored Cir-
cuits i n this section.
N O T E : V a r i o u s d i a g n o s t i c p r o c e d u r e s m a y actually
c a u s e a d i a g n o s t i c monitor to s e t a D T C . W h e n a
repair i s c o m p l e t e d a n d verified, u s e the D R B s c a n
tool to e r a s e all D T C ' s a n d e x t i n g u i s h the MIL.
Technicians can display stored DTC's by two differ-
ent methods. Refer to Diagnostic Trouble Codes i n
this section. For DTC information, refer to charts i n
this section.