68
Lit. No. 21857
June 15, 2003
PLOW HEADLAMP TEST
1. Verify correct harness and wire
installation to the headlamp relays.
2. All bulbs must be good.
3. Connect all harnesses at the front
of the vehicle .
4. Turn vehicle headlamp switch on.
For vehicles with Daytime
Running Lamps (DRLs), turn
NO
YES
NO
YES
YES
YES
NO
NO
YES
YES
NO YES
NO
NO
YES
NO
At each headlamp relay, is
there 12v at terminal 30 with
green (high beam) or yellow
(low beam) wires?
Apply (+) 12v to relay terminal 87
with white (high beam) or black
(low beam) wires. Do plow
headlamps work?
With (+) 12v applied at
terminal 87, is there 12v at the
black or white wires in the
plow headlamp connectors at
the bulb?
Check vehicle output from
headlamp connector to plug-in
harness. Repair vehicle
electrical system or open wires
in plug-in harness.
Is there 12v at each relay
terminal 86 with brown or (DRL)
pink wire?
Check brown wire connection to
vehicle park lamp circuit or
(DRL) pink wire connection to
vehicle accessory wire or
fusebox. Repair or replace
open (DRL) pink or brown wire.
Disconnect 12-pin connector. Is
there 12v at terminal #6 (high
beam, white wire) or terminal #2
(low beam, black wire) on vehicle
side?
Corresponding wire is
open in vehicle harness.
Repair wire or replace
harness.
Corresponding wire is
open in plow harness.
Repair wire or replace
harness.
Attach a ground jumper wire to relay
terminal 85 with black/orange wire.
Do plow lights come on?
Replace headlamp relay.
Remove jumper wire from relay.
Disconnect 12-pin connector. Attach
ground jumper wire to terminal #5 on
vehicle side. Is there 12v at terminal
#6 (high beam) or terminal #2 (low
beam)?
Black/orange ground wire in
vehicle harness is open.
Repair wire or replace harness.
Reconnect 12-pin
connector. Attach
ground jumper to (-)
motor terminal. Do plow
lights come on?
Black/orange wire in
plow harness is open.
Repair wire or replace
harness
.
Poor ground between
battery and motor (-)
terminal. Repair vehicle
or plow (-) battery cable.
Black/orange ground
wire in plow harness is
open. Repair wire or
replace harness.
ignition on. DRL equipped
vehicles have a pink wire instead
of a brown wire on relay terminal
86.
5. Refer to the Electrical Schematic,
Headlamp Test diagram and 12-
Pin Connector diagram.
1
2
3
4
5
6
7
8
9
10
11
12
Low Beam
Headlamp
Ground
High Beam
Headlamp
Left Turn
Right Turn
Park
12-Pin
Connector