Lull 944E-42 Service Manual - Manual (Page 643)

9.133 Model 644E-42/944E-42 Rev. 6/04
Electrical System
With the ignition ON and
the brake pedal depressed,
brake lights remain OFF.
If one brake light is not ON
with the brake pedal
depressed, check for
battery voltage at that
taillight connector, pins 1 & 4,
wire [RLG1] (BLK) &
[BL2C] (GRY) (Left),
[RLG2] (BLK) &
[BL2B] (GRY) (Right).
If neither brake light is ON
with the brake pedal
depressed, check for battery
voltage at brake pedal switch
pin 1, wire [BL1] (RED/WHT).
Not OK If OK
With the brake pedal
depressed, check for
voltage at brake
pedal switch pin 2,
wire [BL2] (GRY).
Not OK If OK
Replace bulb.
Replace cab
roadlight
harness.
Not OK If OK
With the brake pedal
depressed, check for
voltage at pin F, wire
[BL2] (GRY) on
roadlight female
connector.
Replace brake
pedal switch.
If OK
Check for battery
voltage at that
taillight connector,
pins 1 & 4, wire
[RLG1] (BLK) &
[BL2C] (GRY) (Left),
[RLG2] (BLK) &
[BL2B] (GRY) (Right).
If OK
Replace bulb.
Check for proper
ground at wire
[EG7] (BLK) at
ground buss bar.
Replace vehicle
roadlight
harness.
Not OK If OK
Clean, tighten
and recheck.
Not OK
Replace cab
roadlight
harness.
Not OK
Check for proper
ground at wire
[EG7] (BLK) at
ground buss bar.
Replace vehicle
roadlight
harness.
Not OK If OK
Clean, tighten
and recheck.
Before troubleshooting any
electrical circuit, ALWAYS begin by
checking the following:
1. Fuses.
2. All connections relating to circuit
are clean and tight.
3. All grounding straps are intact
and securely fastened, refer to
Section 9.1.12, “General Overview
(Vehicle Ground Strap
Locations).”
4. Verify that the turn signals circuit
is operating. If not, follow the
steps listed at, Section 9.8.41,
“Light Power Relay Circuit &
Troubleshooting (Option),” before
troubleshooting the brake lights
circuit.
5. If one of the brake lights work, the
circuit is fine, the failed bulb
needs to be replaced.