P0108 Map Sensor Circuit High Voltage - Isuzu 2000 Trooper Workshop Manual

6E–148
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0108 MAP Sensor Circuit High Voltage
Circuit Description
The manifold absolute pressure (MAP) sensor responds
to changes in intake manifold pressure (vacuum). The
MAP sensor signal voltage to the powertrain control
module (PCM) varies from below 2 volts at idle (high
vacuum) to above 4 volts with the key "ON," engine not
running or at wide-open throttle (low vacuum).
The MAP sensor is used to determine manifold pressure
changes while the linear EGR flow test diagnostic is being
run (refer to DTC P0401 ), to determine engine vacuum
level for some other diagnostics and to determine
barometric pressure (BARO). The PCM monitors the
MAP signals for voltages outside the normal range of the
MAP sensor. If the PCM detects a MAP signal voltage
that is excessively high, DTC P0108 will be set.
Conditions for Setting the DTC
D No TP sensor DTCs present.
D Engine is running for more than 10 seconds.
D Throttle position is below 3% if engine speed is below
1000 RPM.
D Throttle position is below 10% if engine speed is above
1000 RPM.
D The MAP sensor indicates an intermittent manifold
absolute pressure above 80 kPa for a total of
approximately 10 seconds over a 16-second period.
Action Taken When the DTC Sets
D The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
D The PCM will default to a BARO value of 79.3 kPa.
D The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
D The PCM will turn the MIL "OFF" on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
D A history DTC P0108 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D DTC P0108 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
D The MAP sensor shares a 5 Volt reference with the
Fuel Tank Pressure Sensor. If these codes are also set,
it could indicate a problem with the 5 Volt reference
circuit.
D The MAP sensor shares a ground with the Fuel Tank
Pressure Sensor (Vapor Pressure Sensor), the ECT
sensor, and the Transmission Fluid Temperature
sensor.
D Poor connection at PCM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.
D06RY00165