Indicator Lamps; All Lamps Out; One Lamp Out - Jeep 1987 Wrangler Workshop Manual

INDICATOR LAMPS
®
UPSHIFT
(2.5L/5SPD
ONLY)
" 1 INDICATOR
LAMP
PANEL
20 GRY
W/TR
A7
20 GRY
W/TR
18 BRN
F6
20 GRY
W/TR
B6
18 GRY
W/TR
X X
BRAKE PRESSURE
WARNING SWITCH
(CLOSES WITH
UNEQUAL BRAKE
PRESSURE)
18 BRN
W/TR
18 TAN
W/TN
C121
IP
18 BLK
W/TR
H6
f
C100
C140 18 BLK
W/TR
1J
UPSHIFT
SWITCH
(OPEN IN
HIGH GEAR)
C120
C100
18 TAN
W/TR
C « C140
C103
M
S
OFF
IGNITION
SWITCH
18 GRY
W/TR
• GROUNDS
I DURING
I CRANKING
FOR BULB
!CHECK
18 PNK
W/TR
COMMAND
TRAC
SWITCH
(VACUUM
(OPERATED)
S J | UPSHIFT
' DISCONNECT
z
PARK
BRAKE
SWITCH
D2-1
DESCRIPTION
The brake, upshift and 4WD lamps are located in the
indicator lamp panel above the steering column. The
lamps share a common battery feed connection through
the ignition switch and GAUGES FUSE. Switches in
series with ground circuits complete the indicator lamp
circuit.
The 4WD indicator lamp circuit is completed by a
vacuum switch located below the battery. When vacuum
is applied to the axle mounted shift motor, it is also ap-
plied to the indicator lamp switch.
The upshift switch is normally closed to complete the
circuit from the lamp to the electronic control module.
Since further shifts are no longer possible in fifth gear,
the switch is opened to prevent operation of the lamp.
With a completed circuit the indicator lamp will be illu-
minated by the ECU. The numerous inputs received by
the ECU enable it to indicate through the lamp the best
time to upshift to a higher gear.
The brake indicator is a dual function lamp. It will in-
dicate an unequal pressure condition in the brake hydrau-
lic system and it will also indicate when the parking brake
is engaged. Separate switches are used for each indicator
lamp function. A switch mounted on the brake pedal
assembly will close a ground circuit whenever the parking
brakes are applied. A second switch is installed in the
brake hydraulic lines near the master cylinder. If the
switch is balanced by equal pressure on both ends of the
switch valve, the valve remains centered and the lamp re-
mains off. If the valve is shifted by unequal pressure be-
tween the front or rear brake hydraulic systems, the lamp
circuit is connected to ground. To make sure the brake
lamp is functional before the vehicle is driven, it is il-
luminated through a ground circuit when the ignition
switch is turned to the START position.
TROUBLESHOOTING — A l l Lamps Out
1. FUSE: Ignition ON
TEST
O K
N O T O K
Inspect GAUGES fuse Not blown Replace fuse
Battery side of fuse 12 volts Repair open from ignition switch
2. BATTERY SUPPLY: Ignition ON
T E S T O K N O T O K
Terminal 5 at connector
C121
12 volts Repair open from fuse panel
TROUBLESHOOTING — O n e Lamp Out
1. BULB: Ignition ON
T E S T O K N O T O K
Across bulb terminals Zero ohms Replace bulb
Indicator Lamps
38 Indicator Lamps