Dodge ram truck 3500 1996 Service Manual page 1285

B R
FUEL SYSTEM 14 - 51
D I A G N O S I S A N D T E S T I N G (Continued)
A = GROUND
B = OUTPUT VOLTAGE SIGNAL
C = 5-VOLT SUPPLY
MAP
I SENSOR
C
B
A
8056d9f7
Fig. 59 MAP Sensor Connector Terminals—3.9U
5.2U5.9L Engines
(5) Test the MAP sensor ground circuit at sensor
connector terminal—A (Fig. 59) and PCM connector
A-4. Repair the wire harness i f necessary.
Refer to Group 8W, Wiring Diagrams for cavity
locations.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
TEST—8.0L ENGINE
To perform a complete test of the MAP sensor (Fig.
60) and its circuitry, refer to DRB scan tool and
appropriate Powertrain Diagnostics Procedures man­
ual. To test the MAP sensor only, refer to the follow­
ing:
Fig. 60 Manifold Absolute Pressure (MAP) Sensor—
8.0L Engine
CAUTION: When testing the MAP sensor, be sure
that the harness wires are not damaged by the test
meter probes.
(1) Test the MAP sensor output voltage at the
MAP sensor connector between terminals 1 and 3
(Fig. 61). With the ignition switch ON and the engine
OFF, output voltage should be 4-to-5 volts. The volt­
age should drop to 1.5-to-2.1 volts with a hot, neutral
idle speed condition.
CAVITY FUNCTION
1
5-Volt Supply
2 Sensor Ground
3 Map Sensor Signal
805dd851
Fig. 61 MAP Sensor Connector Terminals—8.0L
Engine
(2) Test powertrain control module (PCM) cavity
A-27 for the same voltage described above to verify
the wire harness condition. Repair as necessary.
(3) Test MAP sensor supply voltage at sensor con­
nector between terminals 1 and 2 (Fig. 61) with the
ignition ON. The voltage should be approximately 5
volts (±0.5V). Five volts (±0.5V) should also be at
cavity A-17 of the PCM wire harness connector.
Repair or replace the wire harness as necessary.
(4) Test the MAP sensor ground circuit at sensor
connector terminal—2 (Fig. 61) and PCM connector
A-4. Repair the wire harness i f necessary.
Refer to Group 8W, Wiring Diagrams for cavity
locations.
HEATED OXYGEN (02S) SENSORS—3.9L/5.2L/
5.9L LCD ENGINES
To perform a complete test of the 02S sensors and
their circuitry, refer to the DRB scan tool and appro­
priate Powertrain Diagnostics Procedures manual. To
test the 02S sensors only, refer to the following:
The upstream 02S sensor is located on the inlet
end of the catalytic converter (Fig. 62).
The downstream 0 2 S sensor is located on the out­
let end of the catalytic converter (Fig. 62).
Each 02S heating element can be tested with an
ohmmeter as follows: