Lighting - Checking Bulb Failure Modules Operation
88jaguar02BULB FAILURE
JAGUAR DIAGNOSTIC SYSTEM
NO: 24
Model: XJ6 3.6 Date: JULY, 1988
KEY POINTS: BULB FAILURE MODULES SYSTEM OPERATION
Software Issue 4010 incorporates an improved program for checking bulb failure modules when the bulb failure VCM warning is illuminated but no bulb failure exists.
The bulb failure VCM warning can be activated by the following three different circuits within the bulb failure system:
1) General Bulb Failure Warning:
The VCM will display "Bulb Failure" when one or more of the following bulbs are causing an open circuit:
^ Headlights
^ Parking Lights
^ Side Marker Lights
^ Reverse Lights
^ License Plate Lights
^ Front/Rear Fog Lights
If a bulb failure module senses an open bulb circuit (such as a broken filament), the bulb failure module will ground the pink/slate wire that terminates at instrument pack connector LB54 pin 32. This will illuminate the "bulb failure" display.
NOTE: The high mounted stop lamp is not checked by the bulb failure warning system.
FIGURE 1:
2) Turn Signal and Hazard System (Fig. 1):
The VCM will display "Bulb Failure" when a turn signal or stop lamp bulb is causing an open circuit.
If a bulb failure module senses an open bulb circuit, the bulb failure module will ground either the right wire (pink/green) or left wire (pink/red) that terminates at the CPU. When the CPU senses this ground, it applies battery voltage to the yellow wire which terminates at instrument pack via connector LB 14 pin 2. This will illuminate the "Bulb failure" display.
FIGURE 2:
3. Disconnection Loop (Fig. 2)
The VCM will display "Bulb Failure" if a connector between a bulb failure module and the CPU is not connected (open circuit). The disconnected loop maintains a constant ground at the appropriate pins of the CPU via the bulb failure modules. When the ground is broken, the CPU switches battery voltage to the yellow wire that terminates at instrument pack via connector LB 14 pin 2. This illuminates the "Bulb Failure" display.
WIRING COLOR CODE
N BROWN Y YELLOW
B BLACK O ORANGE
W WHITE S SLATE (GRAY)
K PINK L LIGHT
G GREEN U BLUE
R RED P PURPLE
When a wire has two color code letters, the first letter indicates the main color and the second letter indicates the tracer color.
EXAMPLE: WK = white with a pink tracer. PGS = purple with a green and slate tracer