Installation - Without Cargo Box; Backup Lamp Switch Description; Operation; Diagnosis And Testing - Backup Lamp Switch - Dodge RAM 1500 1998 Owner's Manual

8L - 8 LAMPS/LIGHTING - EXTERIOR
BACKUP LAMP (Continued)
(2) Install the lamp back plate onto the tail lamp
unit.
(3) Install the tail lamp unit (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING
LAMP UNIT - INSTALLATION).
(4) Reconnect the negative battery cable.

INSTALLATION - WITHOUT CARGO BOX

(1) Install the backup lamp bulb into the backup
lamp socket by pushing inward and rotating it clock-
wise.
NOTE: Install the tail lamp lens with the clear por-
tion (back-up lens) at the top of the housing. Make
sure that the gasket is correctly in place and not
twisted or torn.
(2) Position the tail lamp lens and gasket onto the
tail lamp unit.
NOTE: Do not overtighten the tail lamp lens screws
or damage to the tail lamp lens may result.
(3) Install the four screws that secure the tail
lamp lens to the tail lamp unit. Tighten the screws
securely.
(4) Reconnect the negative battery cable.
BACKUP LAMP SWITCH
DESCRIPTION
Fig. 2 Backup Lamp Switch - Typical
1 - MANUAL TRANSMISSION
2 - BACKUP LAMP SWITCH
3 - ENGINE WIRE HARNESS
Vehicles equipped with a manual transmission
have a normally open, spring-loaded plunger type
- EXTERIOR/TAIL
back-up lamp switch (Fig. 2). The backup lamp
switch is located in a threaded hole on the side of the
manual transmission housing. The backup lamp
switch has a threaded body and a hex formation near
the plunger end of the switch, and an integral con-
nector at the opposite end of the switch. When
installed, only the connector and the hex formation
are visible on the outside of the transmission hous-
ing. Vehicles with an optional electronic automatic
transmission have a Transmission Range Sensor
(TRS) that is used to perform several functions,
including that of the backup lamp switch. The TRS is
described in further detail elsewhere in this service
information. The backup lamp switch cannot be
adjusted or repaired and, if faulty or damaged, the
entire switch unit must be replaced.

OPERATION

The backup lamp switch controls the flow of bat-
tery voltage to the backup lamp bulbs through an
output on the back-up lamp feed circuit. The switch
plunger is mechanically actuated by the gearshift
mechanism within the transmission, which will
depress the switch plunger and close the switch con-
tacts whenever the reverse gear has been selected.
The switch receives battery voltage through a fuse in
the Integrated Power Module (IPM) on a fused igni-
tion switch output (run) circuit whenever the ignition
switch is in the On position. A take out of the engine
wire harness connects the backup lamp switch to the
vehicle electrical system. The backup lamp switch
and circuits can be tested using conventional diag-
nostic tools and methods.
DIAGNOSIS AND TESTING - BACKUP LAMP
SWITCH
(1) Disconnect and isolate the battery negative
cable.
(2) Raise and support the vehicle.
(3) Locate and disconnect the engine wire harness
connector for the backup lamp switch.
(4) Check for continuity between the two terminal
pins in the backup lamp switch connector.
(a) With the gear selector lever in the Reverse
position, there should be continuity.
(b) With the gear selector lever in any position
other than Reverse, there should be no continuity.
DR