I21622
B
G–Y*1
IF1
HEAD
Relay
2
J/B No. 1
Body ECU
Battery
2
1
3
4
2
2
2
W
To Headlight
*1: w/ Daytime Running Light
*2: w/o Daytime Running Light
R/B No. 2
R–W*1
R–W*1
6
7
D8
Daytime Running
Light Relay
B
J1
J/C
G–Y*1
R–W*2
R–W*2
13
5
7
1C
1K
1L
H–LP
H
DI–786
–
DIAGNOSTICS
BODY CONTROL SYSTEM
1048
Author:
Date:
2003 TOYOTA TACOMA (RM1002U)
Headlight Relay Circuit
CIRCUIT DESCRIPTION
Headlight relay will be on by operating the headlight switch. The transistor which activates the taillight relay
has two sorts: one is activated directly by the headlight switch for fail safe and another is activated by CPU.
The one activated by CPU has two systems and prevents the headlight from turning off at the time of one
system trouble in the automatic operation circuit.
WIRING DIAGRAM
DI83K–04
–
DIAGNOSTICS
BODY CONTROL SYSTEM
DI–787
1049
Author:
Date:
2003 TOYOTA TACOMA (RM1002U)
INSPECTION PROCEDURE
1
Check headlight relay (See page BE–17).
NG
Replace headlight relay.
OK
2
Check for harness and connector between headlight relay and body ECU, and
battery and headlight relay (See page IN–28).
NG
Repair or replace harness or connector.
OK
Proceed to next circuit inspection shown in
problem symptoms table (See page
DI–773).