Toyota Highlander Electrical Wiring Diagrams 2014-2019 PDF

2014-2019 Index

Power Distribution, Grounding & Communication Networks

• Power source distribution wiring, charging system schematics, and ignition circuits for 1AR-FE, 2GR-FE, and 2GR-FKS engine variants.
• Ground point distribution layouts and CAN multiplex communication system schematics for Left-Hand Drive (LHD) and Right-Hand Drive (RHD) configurations.
• DLC3 diagnostic connector wiring and trailer towing option connector circuits.

Engine Management & Powertrain Circuits

• Engine control unit (ECU) wiring, automatic transmission ECT/indicator circuits, and cruise control schematics for 1AR-FE, 2GR-FE, and 2GR-FKS engines.
• Cooling fan control wiring and 4WD system schematics with specific distinctions for vehicles produced before and from November 2016.

Chassis, Brakes & Steering Electronics

• Anti-lock Brake System (ABS), Brake Assist, Electronic Brake-force Distribution (EBD), Hill-Start Assist Control, Downhill Assist Control, TRC, and VSC circuit diagrams categorized by pre- and post-November 2016 production runs.
• Electric Power Steering (EPS) system control wiring for LHD and RHD models.

Driver Assistance, Safety & Restraint Systems

• Advanced driver assistance circuits including Dynamic Radar Cruise Control, Lane Departure Alert, and Pre-Collision / Pre-Crash Safety systems (specifying pre- and November 2016 production splits).
• Supplemental Restraint System (SRS) airbag wiring and seat belt warning circuits.

Exterior Lighting, Vision & Window Systems

• Headlight schematics for halogen and LED types, automatic headlight beam level control, headlight cleaners, automatic light control, and light auto-turn-off systems.
• Front and rear fog lights, taillights, illumination circuits, stop lights, back-up lights, turn signals, and hazard warning light wiring.
• Front and rear wipers and washers (with and without auto wiper systems), automatic glare-resistant electrochromic (EC) mirrors, remote control mirrors (with and without seat position memory), mirror heaters, windshield deicers, and rear window defoggers.

Interior, Climate & Infotainment Systems

• Air conditioning climate control schematics, combination meters, instrument cluster displays, clocks, and power outlet distribution.
• Audio, navigation, and monitor systems covering 6-speaker, 12-speaker, and navigation receiver configurations, back guide monitors, rear view monitors, and panoramic view monitor systems.
• Convenience electronics covering power windows (with/without rear jam protection), power seats (driver and passenger with/without memory), heated steering wheels, sliding roofs, power back doors, seat heaters, and climate control seats.

Access, Security & Telematics Systems

• Smart entry and start systems, immobiliser wiring, steering lock control, door lock controls, back door openers, glass hatch openers, wireless door lock control, and double locking.
• Theft deterrent systems, key reminder circuits, and telematics system schematics.

Component Location & Relay Guide

• Comprehensive physical component positioning, wiring harness routings, and ground point locations across body panels, seats, instrument panels, and engine compartments for 1AR-FE, 2GR-FE, and 2GR-FKS engines in LHD and RHD layouts.
• Detailed relay box and junction block locations, including inner circuit diagrams for relay blocks (R/B No. 5, No. 6, Engine Room R/B No. 1 and No. 2), instrument panel junction blocks (J/B), and CAN junction connectors.

ADAS Integration & The November 2016 Split

In practical diagnostics, treating a 2015 model the exact same as a 2018 model will lead you straight into a wall. Toyota significantly overhauled the safety architecture in November 2016.

If a vehicle rolls into the bay with a disabled Dynamic Radar Cruise Control or a malfunctioning Pre-Collision System, you need to know exactly which generation of the wiring harness you are testing. This technical document explicitly maps out the transition. It separates the early Pre-Crash Safety circuits from the heavily integrated post-2016 setups, allowing you to back-probe the millimeter-wave radar and forward-facing camera modules without accidentally shorting out the active CAN bus.

Multiplex Communication & CAN Junctions

Modern three-row crossovers operate as rolling computer networks rather than traditional mechanical vehicles. A common workshop situation involves a dead infotainment screen paired with an inoperative Power Back Door.

Inexperienced techs will start replacing individual components, completely missing the fact that both systems rely on the overarching Multiplex Communication System. By utilizing the extensive CAN network schematics provided in this resource, you can trace the data lines directly to the No. 1 and No. 2 CAN Junction Connectors. If you discover water intrusion under the dashboard corroding one of these central hubs, you can quickly verify the voltage drop across the communication pins instead of wasting hours tearing apart the tailgate actuator.

Engine Architecture: 1AR-FE vs. 2GR-FE / 2GR-FKS

Under the hood, the electrical variations are substantial across the production run. The powertrain options range from the standard 1AR-FE four-cylinder to the older 2GR-FE V6, eventually transitioning to the highly complex 2GR-FKS with D-4S dual fuel injection.

Tracking a lean condition or an intermittent ignition fault requires precise pinout data. The factory electrical schematics separate the Engine Control and Ignition logic for all three distinct powerplants. You get detailed routing for the smart entry immobilizer loops, ECT (Electronic Controlled Transmission) indicators, and fuel pump control modules. For this reason, you can perform highly accurate multimeter checks at the ECM to confirm sensor health before making the expensive decision to tear down the intake manifold.

Ground Point & Component Locators

An overlooked, heavily corroded ground terminal is often the root cause of countless electrical headaches. Tracking down a parasitic draw or a flickering Headlight Beam Level motor requires knowing exactly where the circuit grounds to the chassis.

This PDF manual features a massive, highly detailed Component and Ground Point Locator section spanning dozens of pages. It visually maps the specific harness routing through the engine compartment, instrument panel, and seats for both LHD and RHD configurations. You will know exactly which kick panel to remove to access the Central Junction Box or the specific Engine Room R/B Assembly, drastically cutting down your diagnostic teardown time.

Pro-Level Digital Access & Guarantee

When a high-tech crossover is taking up a lift, waiting on physical manuals hurts your bottom line. We guarantee immediate delivery of your diagnostic data. Our encrypted checkout system easily processes Apple Pay, Google Pay, PayPal, and standard credit cards.

The instant your payment clears, a download link for this massive 2,819-page PDF is sent directly to your inbox, and a secure backup is logged in your customer profile. You receive a 10-day window to utilize up to 10 downloads, ensuring you can save the file to your shop's primary computer, a diagnostic tablet, and your phone. If a firewall blocks your download on the shop floor, simply reach out—we will issue a direct Dropbox backup link immediately. Need a visual on the digital download process? Watch our quick guide here: https://servicemanuals.info/How-to-Download.mp4.

Frequently Asked Questions

A 2017 model has a faulty Blind Spot Monitor. Are the radar sensor data lines mapped here?
Yes. The Blind Spot Monitor System has its own dedicated circuit layout. You can trace the power, ground, and multiplex communication lines from the rear bumper sensors directly back to the main instrument panel junction, helping you accurately rule out rear-end collision damage to the harness.

Will this resource show me the physical location of the relays for the Power Back Door?
Absolutely. The document includes extensive Relay Location maps covering the Body, Engine Compartment, and the inner circuits of the Instrument Panel J/B Assembly, so you can quickly find and test the liftgate relays without unnecessary interior disassembly.

How detailed is the Toyota Highlander parasitic draw diagnosis mapping for models with the Smart Entry system?
Highly detailed. The schematics isolate the Smart Entry & Start System, breaking down the constant power feeds from the Power Source circuit. This allows you to track standby voltage drops across the door oscillators and the certification ECU to determine exactly what is keeping the network awake.

Can I search this massive document by wire color or specific connector pin numbers?
Yes, this is a fully text-searchable PDF. If your scan tool flags a fault at a specific connector (e.g., on the 2GR-FKS engine control harness), you can use the search function to jump straight to that specific pinout instead of scrolling manually through nearly 3,000 pages.