
RENR9348-01 131
Troubleshooting Section
Repair: The correct supply voltage is reaching
the ECM relay. T
he circuit for the emergency stop
switch is operating correctly at this time. There
may be an intermittent condition in the harness or
in a connector
.
If an intermittent electrical problem is suspected,
refer to Trou
bleshooting, “Electrical Connectors -
Inspect”.
If a problem i
s suspected in the circuit for the ECM
relay, refer to Troubleshooting, “Electrical Power
Supply Circuit - Test”.
STOP.
•
Not OK – The vo
ltages are correct for the
conditions that are stated above.
Repair: .The
circuit is OK at the engine interface
connector, but the ECM r elay is not receiving the
correct voltage. There is a problem in the circuit
between the
engine interface connector and the
connector for the ECM relay. Repair the harness
and/or the connectors. Replace parts, if necessary.
STOP.
i02410299
Engine Pressure Sen sor Open
orShortCircuit-Test
SMCS Code: 1439-038-PX
System Ope
ration Description:
Use this procedure to troubleshoot any suspect
problems w
ith the circuits for the following sensors:
•
Atmospheric pressure sensor
•
Intake manifold pressure sensor
•
Engine oil
pressure sensor
•
Fuel pressure sensor
This procedure covers the following open circuit
diagnostic codes and short circuit diagnostic codes:
•
94-03 Fuel Pressure open/short to +batt
•
94-04 Fuel
Pressure short to ground
•
100-03 Engine Oil Pressure open/short to +batt
•
100-04 Engine Oil Pressure short to ground
•
274-03 Atm
ospheric Pressure open/short to +batt
•
274-04 Atmospheric Pressure short to ground
•
1785-03 Intake Manifold Pressure Sensor voltage
high
•
102-04 Intake Manifold Pressure Sensor voltage
low
The 5 volt sensor supply provides power to all
5voltsensors
. The Electronic Control Module
(ECM) supplies 5.0 ± 0.2 VDC to terminal A of
each sensor connector. The sensor return from the
ECM connecto
r goes to terminal B of each sensor
connector. The sensor supply is output short circuit
protected. A short circuit to the battery will not
damage the ci
rcuit inside the ECM.
Pull-up Voltage
The ECM continuously outputs a pull-up voltage on
the circuit for the sensor signal wire. The ECM uses
this pull-u
p voltage in order to detect a problem in the
signal circuit. When the ECM detects the presence
of a voltage that is above a threshold on the signal
circuit, t
he ECM will generate a 03 diagnostic code
for the sensor.
If the sens
or is disconnected at the sensor connector,
the presence of pull-up voltage at the sensor
connector indicates that the wires from the sensor
connector
to the ECM are OK. If the sensor is
disconnected at the sensor connector, the absence
of pull-up voltage at the sensor connector indicates
a problem
in the signal wire. If the sensor is
disconnected at the sensor connector and the voltage
at the sensor connector is different from pull-up
voltage,
the signal wire may be shorted to another
wire in the harness.