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System Trouble Shooting

NOTE: Body Electronic Control Unit (ECU) is connected to multiplex communication system. Ensure no faults exist in multiplex communication system before performing trouble shooting.

Trouble shooting is available for anti-theft and keyless entry systems. Determine under what conditions the system does not operate or malfunctions and then perform specified test(s) listed under SYSTEM TESTS . If more than one circuit is to be inspected, perform tests in order listed. See appropriate TROUBLE SHOOTING SYMPTOMS table.

TROUBLE SHOOTING SYMPTOMS (ANTI-THEFT SYSTEM)

Problem & (1) Circuit To Be Inspected Go To Test No.
Anti-Theft System Cannot Be Set
Theft-Deterrent Indicator Circuit 14 
Key Unlock Warning Switch Circuit 6 
Door Courtesy Switch Circuit 12 
Door Unlock Detection Switch Circuit 9 
Hood Courtesy Switch Circuit 13 
Liftgate Courtesy Switch Circuit 17 
Back Door ECU (4)
Body ECU (5)
Cannot Be Cancelled When Ignition Is On With A Key
Key Unlock Warning Switch Circuit 6 
Ignition Switch (2)
Body ECU (5)
Cannot Be Cancelled When Unlocking Back Door With Key
Door Courtesy Switch Circuit 12 
Body ECU (5)
Headlights Do Not Illuminate
Headlight Relay Circuit 5 
Body ECU (5)
Taillights Do Not Illuminate
Taillight Relay Circuit 4 
Body ECU (5)
Theft-Deterrent Horn Or Horn Does Not Sound
Theft-Deterrent Horn Circuit 16 
Horn Circuit 15 
Body ECU (5)
During Warning Condition, System Cannot Be Cancelled By Unlocking Door With Key
Door Key Lock & Unlock Switch Circuit 10 
Back Door ECU (4)
Body ECU (5)
During Warning Condition, System Cannot Be Cancelled By Unlocking Door With Transmitter
Transmitter (3)
Back Door ECU (4)
Body ECU (5)
During Warning Condition, System Cannot Be Cancelled By Turning Ignition On
Ignition Switch (2)
Key Unlock Warning Switch Circuit 6 
Body ECU (5)
(1) If more than one circuit is to be inspected, perform test on each circuit in the order listed.
(2) See STEERING COLUMN SWITCHES - TRUCKS article.
(3) See KEYLESS ENTRY SYSTEMS - 4RUNNER article.
(4) Test wiring and connectors to back door ECU. If wiring and connectors are okay, test back door ECU and replace as necessary.
(5) Test wiring and connectors to body ECU. If wiring and connectors are okay, test body ECU and replace as necessary.
TROUBLE SHOOTING SYMPTOMS (POWER DOOR LOCK SYSTEM)

Problem & (1) Circuit To Be Inspected Go To Test No.
Lock Or Unlock Will Not Operate With Door Lock Control Switch
Door Lock Control Switch Circuit 11 
Body ECU (2)
Door Key Linked Function Does Not Operate
Door Key Lock & Unlock Switch Circuit 10 
Body ECU (2)
Key Confinement Prevention Function Does Not Operate
Door Key Lock & Unlock Switch Circuit 10 
Body ECU (2)
(1) If more than one circuit is to be inspected, perform test on each circuit in the order listed.
(2) Test wiring and connectors to body ECU. If wiring and connectors are okay, test body ECU and replace as necessary.
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