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8J - 12
INSTRUMENT CLUSTER
BRAKE/PARK BRAKE INDICATOR (Continued)
the translucent outer layer of the overlay when the
indicator is illuminated from behind by the LED,
which is soldered onto the instrument cluster elec-
tronic circuit board. The brake indicator is serviced
as a unit with the instrument cluster.
OPERATION
The brake indicator gives an indication to the vehi-
cle operator when the parking brake is applied, or
when there are certain brake hydraulic system mal-
functions as indicated by a low brake hydraulic fluid
level condition. This indicator is controlled by a tran-
sistor on the instrument cluster circuit board based
upon cluster programming and hard wired inputs
from the park brake switch and the brake fluid level
switch. The brake indicator Light Emitting Diode
(LED) is completely controlled by the instrument
cluster logic circuit, and that logic will only allow
this indicator to operate when the instrument cluster
detects that the ignition switch is in the On position.
Therefore, the LED will always be off when the igni-
tion switch is in any position except On. The LED
only illuminates when it is provided a path to ground
by the instrument cluster transistor. The instrument
cluster will turn on the brake indicator for the follow-
ing reasons:
• Bulb Test - Each time the ignition switch is
turned to the On position the brake indicator is illu-
minated by the instrument cluster for about two sec-
onds as a bulb test.
• Brake Fluid Level Switch Input - Each time
the cluster detects ground on the park brake/brake
fluid level switch sense circuit (brake fluid level
switch closed = brake fluid level low) while the igni-
tion switch is in the On position, the brake indicator
is illuminated. The indicator remains illuminated
until the brake fluid level switch sense input to the
cluster is an open circuit (brake fluid level switch
open = brake fluid level okay), or until the ignition
switch is turned to the Off position, whichever occurs
first.
• Park Brake Switch Input - Each time the
cluster detects ground on the park brake/brake fluid
level switch sense circuit (park brake switch closed =
park brake applied or not fully released) while the
ignition switch is in the On position, the brake indi-
cator is illuminated. The indicator remains illumi-
nated until the park brake switch sense input to the
cluster is an open circuit (park brake switch open =
park brake fully released), or until the ignition
switch is turned to the Off position, whichever occurs
first.
The park brake switch on the park brake pedal
mechanism and the brake fluid level switch in the
brake master cylinder provide a hard wired ground
input to the instrument cluster circuitry through the
park brake/brake fluid level switch sense circuit
whenever the park brake is applied or not fully
released, or whenever the fluid level in the brake
master cylinder is low. The two switches are con-
nected in parallel between ground and the instru-
ment cluster. The park brake switch, brake fluid
level switch, and their input circuit to the instrument
cluster can be diagnosed using conventional diagnos-
tic tools and methods. For proper diagnosis of the
instrument cluster circuitry that controls the brake
indicator, a DRBIII
the appropriate diagnostic information.
BRAKE WEAR INDICATOR
DESCRIPTION
A brake wear indicator is standard equipment on
all instrument clusters. The brake wear indicator is
located near the lower edge of the instrument cluster,
to the left of the multi-function indicator display. The
brake wear indicator consists of the International
Control and Display Symbol icon for "Worn Brake
Linings" imprinted within a rectangular cutout in the
opaque layer of the instrument cluster overlay. The
dark outer layer of the overlay prevents the indicator
from being clearly visible when it is not illuminated.
An amber Light Emitting Diode (LED) behind the
cutout in the opaque layer of the overlay causes the
icon to appear silhouetted against an amber field
through the translucent outer layer of the overlay
when the indicator is illuminated from behind by the
LED, which is soldered onto the instrument cluster
electronic circuit board. The brake wear indicator is
serviced as a unit with the instrument cluster.
OPERATION
The brake wear indicator gives an indication to the
vehicle operator when the brake linings have reached
their wear limits. This indicator is controlled by a
transistor on the instrument cluster circuit board
based upon cluster programming and a hard wired
input from the four brake wear sensors, one at each
wheel. The brake wear indicator Light Emitting
Diode (LED) is completely controlled by the instru-
ment cluster logic circuit, and that logic will only
allow this indicator to operate when the instrument
cluster detects that the ignition switch is in the On
position. Therefore, the LED will always be off when
the ignition switch is in any position except On. The
LED only illuminates when it is provided a path to
ground by the instrument cluster transistor. The
instrument cluster will turn on the brake wear indi-
cator for the following reasons:
• Bulb Test - Each time the ignition switch is
turned to the On position the brake wear indicator is
scan tool is required. Refer to
VA
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