Dodge Viper SRT-10 (ZB). Manual — part 400

The pumping cycle is repeated as the solenoid is

turned on and off. When the evaporative system
begins to pressurize, the pressure on the bottom of
the diaphragm will begin to oppose the spring
pressure, slowing the pumping action. The PCM
watches the time from when the solenoid is de-
energized, until the diaphragm drops down far
enough for the reed switch to change from opened to
closed. If the reed switch changes too quickly, a leak
may be indicated. The longer it takes the reed
switch to change state, the tighter the evaporative
system is sealed. If the system pressurizes too
quickly, a restriction somwhere in the EVAP system
may be indicated.

PUMPING ACTION

During portions of this test, the PCM uses the

reed switch to monitor diaphragm movement. The
solenoid is only turned on by the PCM after the reed
switch changes from open to closed, indicating that
the diaphragm has moved down. At other times
during the test, the PCM will rapidly cycle the LDP
solenoid on and off to quickly pressurize the system.
During rapid cycling, the diaphragm will not move
enough to change the reed switch state. In the state
of rapid cycling, the PCM will use a fixed time
interval to cycle the solenoid.

If the system does not pass the EVAP Leak

Detection Test, the following DTCs may be set:

•

P0442 – EVAP LEAK MONITOR 0.040

9 LEAK

DETECTED

•

P0455 – EVAP LEAK MONITOR LARGE LEAK
DETECTED

•

P0456 – EVAP LEAK MONITOR 0.020

9 LEAK

DETECTED

•

P1486 – EVAP LEAK MON PINCHED HOSE
FOUND

•

P1494 – LEAK DETECTION PUMP SW OR
MECH FAULT

•

P1495 – LEAK DETECTION PUMP SOLENOID
CIRCUIT

ENABLING CONDITIONS TO RUN EVAP LEAK
DETECTION TEST

1. Cold start: with ambient temperature (obtained

from modeling the inlet air temperature sensor
on passenger vehicles and the battery tempera-
ture sensor on Jeep & truck vehicles) between
4°C (40°F) and 32°C (90°F) for 0.040 leak. Be-
tween 4°C (40°F) and 29°C (85°F) for 0.020 leak.

2. Engine coolant temperature within: -12° to -8°C

(10° to 18°F) of battery/ambient.

3. Battery voltage between 10 and 15 volts.

NOTE: If battery voltage drops below 10 volts
for more than 5 seconds during engine
cranking, the evap leak detection test will not
run.

4. Low fuel warning light off (fuel level must be

between 15% and 85%).

5. MAP sensor reading 22 in Hg or above (This is

the manifold absolute pressure, not vacuum).

6. No engine stall during test.

NOTE: The following values are approximate
and vehicle specific. Use the values seen in
pre test/monitor test screen on the DRBIII

T

.

See TSB 25-02-98 for more detail.

A DTC will not set if a one-trip fault is set or if the

MIL is illuminated for any of the following:

•

Purge Solenoid

•

All engine Controller Self Test Faults

•

All Cam and/or Crank Sensor Faults

•

MAP Sensor Faults

•

Ambient/Battery Temperature Sensor Electrical
Faults

•

All Coolant Sensor Faults

•

All TPS Faults

•

LDP Pressure Switch Faults

•

EGR Solenoid Electrical Faults

•

All Injector Faults

•

Baro Out Of Range

•

Vehicle Speed Faults

•

LDP Solenoid Circuit

FIGURE 6 SECTION 1

When the ignition key is turned to “ON”, the LDP

diaphragm should be in the down position and the
LDP reed switch should be closed. If the EVAP

7

GENERAL INFORMATION

system has residual pressure, the LDP diaphragm
may be up. This could result in the LDP reed switch
being open when the key is turned to “ON” and a
P1494 fault could be set because the PCM is expect-
ing the reed switch to be closed.

After the key is turned “ON”, the PCM immedi-

ately tests the LDP solenoid circuit for electrical
faults. If a fault is detected, DTC P1495 will set, the
MIL will illuminate, and the remaining EVAP Leak
Detection Test is cancelled.

NOTE: If battery temperature is not within
range, or if the engine coolant temperature is
not within a specified range of the battery
temperature, the PCM will not run tests for
DTC P1494, P1486, P0442, P0455 and P0441.
These

temperature

calibrations

may

be

different between models.

FIGURE 6 SECTION 2

If DTC P1495 is not set, the PCM will check for

DTC P1494. If the LDP reed switch was closed
when the key was turned to “ON”, the PCM ener-
gizes the LDP solenoid for up to 8 seconds and
monitors the LDP switch. As the LDP diaphragm is
pulled up by engine vacuum, the LDP reed switch
should change from closed to open. If it does not, the
PCM sets a temporary fault (P1494) in memory, and
waits until the next time the Enabling Conditions
are met to run the test again. If this is again
detected, P1494 is stored and the MIL is illumi-
nated. If the problem is not detected during the next
enabling cycle, the temporary fault will be cleared.

However, if the PCM detects the reed switch open

when the key is turned to “ON”, the PCM must
determine if this condition is due to residual pres-
sure in the EVAP system, or an actual fault. The
PCM stores information in memory on EVAP sys-
tem purging from previous engine run or drive
cycles.

If little or no purging took place, residual pres-

sure could be holding the LDP diaphragm up,
causing the LDP switch to be open. Since this is not
a malfunction, the PCM cancels the EVAP Leak
Detection Test without setting the temporary fault.

If there was sufficient purging during the previ-

ous cycle to eliminate EVAP system pressure, the
PCM judges that this is a malfunction and sets a
temporary fault in memory. The next time that the
Enabling Conditions are met, the test will run
again. If the fault is again detected, the MIL will
illuminate and DTC 1494 will be stored. If the fault
is not detected, the temporary fault will be cleared.

FIGURE 6 SECTION 3

If no fault has been detected so far, the PCM

begins testing for possible blockage in the EVAP
system between the LDP and the fuel tank. This is

done by monitoring the time required for the LDP to
pump air into the EVAP system during two to three
pump cycles. If no blockage is present, the LDP
diaphragm is able to quickly pump air out of the
LDP each time the PCM turns off the LDP solenoid.
If a blockage is present, the PCM detects that the
LDP takes longer to complete each pump cycle. If
the pump cycles take longer than expected (approx-
imately 6 to 10 seconds) the PCM will suspect a
blockage. On the next drive when Enabling Condi-
tions are met, the test will run again. If blockage is
again detected, P1486 is stored, and the MIL is
illuminated.

FIGURE 6 SECTION 4

After the LDP blockage tests are completed, the

PCM then tests for EVAP system leakage. First, the
PCM commands the LDP to rapidly pump for 20 to
50 seconds (depending on fuel level) to build pres-
sure in the EVAP system. This evaluates the system
to see if it can be sufficiently pressurized. This
evaluation (rapid pump cycling) may occur several
times prior to leak checking. The LDP reed switch
does not close and open during rapid pumping
because the diaphragm does not travel through its
full range during this part of the test.

FIGURE 6 SECTION 5

Next, the PCM performs one or more test cycles

by monitoring the time required for the LDP reed
switch to close (diaphragm to drop) after the LDP
solenoid is turned off.

If the switch does not close, or closes after a long

delay, it means that the system does not have any
significant leakage and the EVAP Leak Detection
Test is complete.

However, if the LDP reed switch closes quickly,

there may be a leak or the fuel level may be low
enough that the LDP must pump more to finish
pressurizing the EVAP system. In this case, the
PCM will rapidly pump the LDP again to build
pressure in the EVAP system, and follow that by
monitoring the time needed for several LDP test
cycles. This process of rapid pumping followed by
several LDP test cycles may repeat several times
before the PCM judges that a leak is present.

When leaks are present, the LDP test cycle time

will be inversely proportional to the size of the leak.
The larger the leak, the shorter the test cycle time.
The smaller the leak, the longer the test cycle time.
DTC’s may be set when a leak as small as 0.5 mm
(0.020

9) diameter is present.

If the system detects a leak, a temporary fault

will be stored in PCM memory. The time it takes to
detect a .020, .040, or Large leak is based on
calibrations that vary from model to model. The
important point to remember is if a leak is again
detected on the next EVAP Leak Detection Test, the

8

GENERAL INFORMATION

MIL will illuminate and a DTC will be stored based
on the size of leak detected. If no leak is detected
during the next test, the temporary fault will be
cleared.

DIAGNOSTIC TIPS

During diagnosis, you can compare the LDP so-

lenoid activity with the monitor sequence in Figure
6. If the PCM detects a problem that could set a
DTC, the testing is halted and LDP solenoid activ-
ity will stop. As each section of the test begins, it
indicates that the previous section passed success-
fully. By watching to see which tests complete, you
can see if any conditions are present that the PCM
considers abnormal.

For example, if the LDP solenoid is energized for

the test cycles to test for blockage (P1486), it means
that the LDP has already passed its test for P1494.
Then, if the PCM detects a possible blockage, it will
set a temporary fault without turning on the MIL
and continue the leak portion of the test. However,
the PCM will assume that the system is already
pressurized and skip the rapid pump cycles.

Always diagnose leaks, if possible, before discon-

necting connections. Disconnecting connections
may mask a leak condition.

Keep in mind that if the purge solenoid seat is

leaking, it could go undetected since the leak would
end up in the intake manifold. Disconnect the purge
solenoid at the manifold when leak checking. In
addition, a pinched hose fault (P1486) could set if
the purge solenoid does not purge the fuel system
properly (blocked seat). The purge solenoid must
vent the fuel system prior to the LDP system test. If
the purge solenoid cannot properly vent the system
the LDP cannot properly complete the test for
P1486 and this fault can set due to pressure being
in the EVAP system during the test sequence.

Multiple actuation’s of the DRBIII

t Leak Detec-

tion Pump (LDP) Monitor Test can hide a 0.020 leak
because of excess vapor generation. Additionally,
any source for additional vapor generation can hide
a small leak in the EVAP system. Excess vapor
generation can delay the fall of the LDP diaphragm
thus hiding the small leak. An example of this
condition could be bringing a cold vehicle into a
warm shop for testing or high ambient tempera-
tures.

Fully plugged and partially plugged underhood

vacuum lines have been known to set MIL condi-
tions. P1494 and P0456 can be set for this reason.
Always, thoroughly, check plumbing for pinches or
blockage before condemning components.

TEST EQUIPMENT

The Evaporative Emission Leak Detector (EELD)

Miller Special Tool 8404 is capable of visually de-
tecting leaks in the evaporative system and will

take the place of the ultrasonic leak detector 6917A.
The EELD utilizes shop air and a smoke generator
to visually detect leaks down to 0.020 or smaller.
The food grade oil used to make the smoke includes
an UV trace dye that will leave telltale signs of the
leak under a black light. This is helpful when
components have to be removed to determine the
exact leak location. For detailed test instructions,
follow the operators manual packaged with the
EELD.

IMPORTANT

Be sure that the PCM has the latest software

update. Reprogram as indicated by any applicable
Technical Service Bulletin. After LDP repairs are
completed, verify the repair by running the
DRBIII

t Leak Detection Pump (LDP) Monitor Test

as described in Technical Service Bulletin 18-12-99.

3.2.5

NON-MONITORED CIRCUITS

The PCM does not monitor the following circuits,

systems, and conditions even though they could
have malfunctions that result in driveability prob-
lems. A diagnostic code may not be displayed for the
following conditions. However, problems with these
systems may cause a diagnostic code to be displayed
for other systems. For example, a fuel pressure
problem will not register a diagnostic code directly,
but could cause a rich or lean condition. This could
cause an oxygen sensor, fuel system, or misfire
monitor trouble code to be stored in the PCM.

Engine Timing − The PCM cannot detect an

incorrectly

indexed

timing

chain,

camshaft

sprocket, or crankshaft sprocket. The PCM also
cannot detect an incorrectly indexed distributor or
Cam Sensor.(*)

Fuel Pressure − Fuel pressure is controlled by

the fuel pressure regulator. The PCM cannot detect
a clogged fuel pump inlet filter, clogged in-line filter,
or a pinched fuel supply.(*)

Fuel Injectors − The PCM cannot detect a

clogged fuel injector, a sticking pintle, or that an
incorrect injector is installed.(*)

Fuel Requirements − Poor quality gasoline can

cause problems such as hard starting, stalling, and
stumble. Use of methanol-gasoline blends may re-
sult in starting and driveability problems. (See
individual symptoms and their definitions in Sec-
tion 6.0 (Glossary of Terms)).

PCM Grounds − The PCM cannot detect a poor

system ground. However, a diagnostic trouble code
may be stored in the PCM as a result of this
condition.

Throttle Body Air Flow − The PCM cannot

detect a clogged or restricted air cleaner inlet or
filter element.(*)

Exhaust System − The PCM cannot detect a

plugged, restricted, or leaking exhaust system.(*)

9

GENERAL INFORMATION

Cylinder Compression − The PCM cannot de-

tect uneven, low, or high engine cylinder compres-
sion.(*)

Excessive Oil Consumption − Although the

PCM monitors the exhaust oxygen content through
the oxygen sensor when the system is in a closed
loop, it cannot determine excessive oil consumption.

NOTE: Any of these conditions could result
in a rich or lean condition causing an oxygen
sensor trouble code to be stored in the PCM,
or the vehicle may exhibit one or more of the
driveability symptoms listed in the Table of
Contents.

3.3

DIAGNOSTIC TROUBLE CODES

Each diagnostic trouble code is diagnosed by

following a specific testing procedure. The diagnos-
tic test procedures contain step-by-step instructions
for determining the cause of trouble codes as well as
no trouble code problems. It is not necessary to
perform all of the tests in this book to diagnose an
individual code. Always begin by reading the diag-
nostic trouble codes using the DRBIII

t.

3.3.1

HARD CODE

A diagnostic trouble code that comes back within

one cycle of the ignition key is a “hard” code. This
means that the problem is present when the PCM
checks that circuit or function. Procedures in this
manual verify if the trouble code is a hard code at
the beginning of each test. When it is not a hard
code, an “intermittent” test must be performed.

Codes that are for OBDII monitors will not set

with just the ignition key on. Comparing these to
non-emission codes, they will seem like an intermit-
tent. These codes require a set of parameters to be
performed (The DRBIII

t pre-test screens will help

with this for MONITOR codes), this is called a
“TRIP”. All OBDII DTCs will set after two or in
some cases one trip failures, and the MIL will be
turned on. These codes require three successful, no
failures, TRIPS to extinguish the MIL, followed by
40 warm-up cycles to erase the code. For further
explanation of TRIPS, Pre-test screens, Warm-up
cycles, and the use of the DRBIII

t, refer to the On

Board Diagnostic training booklet #81-699-97094.

3.3.2

INTERMITTENT CODE

A diagnostic trouble code that is not present every

time the PCM checks the circuit is an “intermittent”
code. Most intermittent codes are caused by wiring
or connector problems. Intermittent conditions that
come and go like this are the most difficult to
diagnose; they must be looked for under specific

conditions that cause them. The following proce-
dures may assist you in identifying a possible
intermittent problem:

•

Visually inspect related wire harness connectors.
Look for broken, bent, pushed out, or corroded
terminals.

•

Visually inspect the related harnesses. Look for
chafed, pierced, or partially broken wire.

•

Refer to any S.T.A.R. Hotline Newsletters or
technical service bulletins that may apply.

•

Use the DRBIII

t data recorder or co-pilot.

3.3.3

STARTS SINCE SET COUNTER

This reset counter counts the number of times the

vehicle has been started since codes were last set or
erased. This counter will count up to 255 start
counts. The number of starts helps determine when
the trouble code actually happened. This is recorded
by the PCM and can be viewed on the DRBIII

t as

STARTS since set. When there are no trouble codes
stored in memory, the DRBIII

t will display “NO

TROUBLE CODES FOUND” and the reset counter
will show “STARTS since set = XXX.” OBDII vehi-
cles will also display a DTC Specific or Global “Good
Trip” counter which will indicate the number of
“Good Trips” since the DTC was set. After 3 consec-
utive “Good Trips,” the MIL is extinguished and the
good trip counter is replaced by a “Warm Up Cycle”
counter. 40 Warm-up Cycles will erase the DTC and
Freeze Frame information.

3.3.4

NO START INFORMATION

IMPORTANT NOTE:

If the Powertrain Control Module has been pro-

grammed, a DTC will be set in the ABS and Air Bag
modules. In addition, if the vehicle is equipped with
a Sentry Key Immobilizer Module (SKIM), Secret
Key data must be updated to enable starting.

FOR ABS AND AIR BAG SYSTEMS:

1. Enter correct VIN and Mileage in PCM.

2. Erase codes in ABS and Air Bag modules.

FOR SKIM THEFT ALARM:

1. Connect the DRBIII

t to the data link connector.

2. Go to Theft Alarm, SKIM, Misc. and place the

SKIM in secured access mode, by using the
appropriate PIN code for this vehicle.

3. Select Update the Secret Key data, data will be

transferred from the SKIM to the PCM (This is
required to allow the vehicle to start with the
new PCM).

4. If three attempts are made to enter secured

access mode using the incorrect PIN, secured

10

GENERAL INFORMATION