This Chilton DIY repair and service manual, covers 1982-1996 Nissan Sentra, Pulsar and NX, U.S. and Canadian models.
Book Excerpt: 1982-1996 Nissan Sentra, Pulsar, NX Repair Manual
DRIVEABILITY AND EMISSION CONTROLS
VACUUM SENSOR | OPERATION
The vacuum sensor is part of the Spark Timing Control System. The sensor provides an engine load signal to the ECM. The sensor converts manifold vacuum into an electrical signal, which is transmitted to the ECM.
The ECM uses this signal, along with coolant temperature and engine speed inputs, to optimize the ignition timing.
1984-1988 FEDERAL ECC 20 PIN CONNECTOR FROM CONTROL UNIT (See Figure 46)
- Disconnect ECC 20 pin connector from control unit.
- Connect a voltmeter between ECC control unit harness terminal 9 and a known good engine ground.
- Disconnect vacuum hose for vacuum sensor and connect vacuum pump to vacuum sensor.
- With no vacuum applied to the sensor, the voltmeter should read approximately 4.0 volts.
NOTE: If the reading was within specifications, proceed to the next step. If the reading was not within specifications, check power supply and wiring to sensor. If okay, replace the sensor and retest.
- Using the vacuum pump, apply 25.0 in. Hg to the sensor. The voltage measurement should be approximately 0.5 volts.
NOTE: If the reading was within specifications, the sensor is okay. If the reading was not within specifications, replace the sensor and retest.
REMOVAL AND INSTALLATION
- Disconnect the vacuum hose from the sensor.
- Disconnect the electrical connector from the sensor.
- Remove the two bolt securing the sensor to the firewall.
- Installation is the reverse of the removal procedure.
VEHICLE SPEED SENSOR
The vehicle speed sensor provides a vehicle speed signal to the ECM. On conventional speedometers, the speed sensor consists of a reed switch which transforms vehicle speed into a pulse signal. The input received from the sensor is used to regulate ignition timing and decell fuel shut off.
TESTING (See Figure 47)
- Remove the speedometer cable and cable pinion housing, from the transaxle.
- Disconnect the 20 pin electrical connector from the ECM.
- Connect an ohmmeter between connector terminal 10 and a known good ground.
- Turn the ignition switch to the ON position.
REMOVAL AND INSTALLATION
(See Figure 43)
- Loosen the adjusting knob at the transaxle as much that is needed.
- Remove the cable insulator nuts at the clutch pedal mount in engine compartment. Disengage the cable from the clutch pedal.
- Lubricate the rubber grommet to ease removal. Remove the grommet from the firewall.
- Disengage the cable from the transaxle mounting bracket.
- Remove the cable from the vehicle.
- Lubricate the rubber grommets and moving parts with heavy grease.
- Install the cable to the vehicle.
- Install the cable bracket nuts and torque to 72-96 inch lbs. (8-11 Nm).
- Adjust the cable as outlined in this section.
Subject: 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996 Nissan Sentra, Pulsar, NX service, maintenance, repair. ISBN-10: 0801988160 | ISBN-13: 9780801988165 | Chilton 52700