Scion xB 2013 Radio Wiring Diagram Complete Pinout Guide
Begin by locating the factory harness behind the dashboard center console–this cluster connects directly to the head unit. Strip 1/4 inch of insulation from each wire, but never splice into the orange illumination circuit unless installing a dimmer-compatible interface. The yellow 12V constant power wire requires a minimum 20-gauge fuse inline within six inches of the battery terminal to prevent fire hazards.
Identify the ground lead (black) and secure it to bare metal using a 10mm bolt tightened to 15 ft-lbs torque; oxide buildup increases resistance, distorting bass frequencies. For aftermarket amplifiers, the rear left speaker’s negative pole (violet/black) must never share ground with the front right (green/black)–this creates a feedback loop audible as midrange static.
Use heat-shrink tubing rated for 90°C over each soldered joint; electrical tape degrades under dashboard temperatures within 12 months. Verify each connection with a multimeter set to 200Ω range–readings above 0.3Ω indicate corrosion requiring re-strip or dielectric grease application. Factory antenna cables terminate in a mini-plug; damage to the internal pin risks permanent signal dropout.
Adapters labeled “Metra 70-8618” include the correct color-coded harness for this platform–bypass generic units to avoid echoed rear-channel outputs. Never reverse the white and gray pairs; doing so inverts phase, canceling vocals. If OEM steering wheel controls lose function, trace the light green/red data bus wire back to the clockspring connector–breaks here mimic control module failures.
Electrical Schematic for Your xB Audio System Upgrade
Locate the factory harness behind the dash panel near the driver’s side kick plate. The 12-pin connector carries power, ground, and speaker outputs–pin 1 (yellow) feeds constant 12V, pin 5 (black) serves as chassis ground, and pins 10-12 (gray, gray/black, white, white/black) handle rear speaker signals.
Match aftermarket stereo wires color-for-color but verify with a multimeter: accessory lead (red) should show voltage only when the ignition is on, while the illumination wire (orange) dims with dashboard lights. Swap green/white and green auxiliary outputs for front door tweeters to avoid phase cancellation.
For subwoofer integration, tap the purple/violet pair from the OEM connector–these remain active at 4 ohms. Avoid bridging to the factory amplifier (if equipped) as its filtering circuit can distort low frequencies. Instead, route directly to a line-output converter set to 0dB gain.
Heat-shrink all splices and secure them away from moving parts. The fuse box under the hood contains a 15A spare slot–repurpose it for the new deck’s power lead, keeping wire gauge at 18AWG minimum to prevent voltage drop during bass peaks.
Rear parking sensors retain function if the reverse trigger (light green) is spliced into the new harness–failure here disables audible alerts. Check continuity between the antenna lead (blue) and the mast; corrosion here manifests as weak FM reception, not amplifier failure.
Ground the new unit to the original bolt point behind the climate control housing–alternative spots may introduce alternator whine. If checksum errors appear on the OEM display, disconnect the battery for 30 seconds to reset the CAN bus.
Installation diagrams from Metra or Scosche include pinouts for USB adapters–use the brown/white lead for iPod detection instead of the default gray, which conflicts with Toyota’s navigation protocol.
Finding the OEM Audio System Plug Interface
Begin by removing the lower dash panel beneath the climate controls–it’s secured with two 10mm bolts and four plastic clips. Slide a trim removal tool along the edges to release the clips without cracking the panel. The harness connector sits directly behind this panel, nestled against the firewall. Look for a rectangular, 16-pin plug with black housing and a white latch on the top; it’s typically positioned to the right of the HVAC duct.
- Disconnect the vehicle’s negative battery terminal before touching any electrical connections to prevent short circuits.
- Recheck the latch orientation: the white tab should face upwards when properly aligned.
- If the connector is missing, inspect the wiring behind the climate control unit–factory splices may be taped or bundled there.
- Non-stock harnesses often use identical pinouts but differ in plug shape; measure the pin spacing (2.54mm pitch) to confirm compatibility.
Trace each wire from the plug to the metal mounting bracket–color codes may vary slightly, but the following are consistent in this model: solid yellow (constant 12V), red with white stripe (switched 12V), black (ground), blue with white (amplifier trigger), orange (illumination), and gray (mute). Probe with a multimeter set to 20V DC to verify voltage on yellow (12V) and red/white (0V with ignition off, 12V when on). If readings deviate, test for blown fuses (15A IGN and 10A ACC in the under-hood box) or corroded grounds near the driver’s kick panel.
Identifying Wire Colors and Pin Functions for Power and Ground
Locate the yellow wire with red stripe (Y/R) at connector C of the audio head unit–this is the primary constant 12V source, typically fused at 10A. Verify voltage with a multimeter while the ignition is off; fluctuations below 11.8V indicate a corroded fuse or wiring fault. The solid black wire (B) serves as the ground, but don’t assume continuity–test resistance between this lead and the chassis, aiming for under 0.5 ohms. If readings exceed this, clean the grounding point with a wire brush and recheck.
Switch-controlled power comes via the red wire (R) at pin 8 of harness A, active only when the key is in the “ACC” or “ON” position. Probe this circuit with the ignition cycled; it should drop to 0V when the key is off. For illumination, trace the green wire with a white stripe (G/W) at pin 5–this dims in sync with dashboard lights, often sharing a circuit with the tail lamp fuse. If brightness doesn’t adjust, inspect the dimmer rheostat or bulb check relay.
Pin assignments vary by trim, but common auxiliary feeds include the blue wire with white stripe (B/W) for amplifier triggers–this carries a low-current signal to external amplifiers, usually 1-3V when the system is powered. Confusing this with the purple wire (P) for antenna power (which delivers 8-12V) risks frying the motorized mast. Always cross-reference the pinout against a verified schematic; aftermarket adapters frequently mislabel “ANT” and “AMP CTRL.”
Integrating a Modern Sound System into Your Compact Hatchback
Begin by locating the factory harness behind the dash panel. The 20-pin connector on the vehicle’s OEM setup follows a standardized pinout, but verify each wire’s function with a multimeter before splicing. Aftermarket adapters like Metra 70-8114 simplify installation by matching harness colors directly–eliminate guesswork by cross-referencing the adapter’s documentation with the vehicle’s wire schematic.
For power delivery, the yellow constant 12V wire (typically 18-20 AWG) requires direct connection to the battery with an inline fuse–no less than 15A for basic units, 20A for systems with amplifiers. The red ignition-switched wire must link to a circuit that energizes only when the key turns; tapping into the vehicle’s accessory port avoids parasitic drain. Ground the black wire to a clean, bare-metal chassis point within 18 inches of the head unit to prevent interference.
| Wire Color (Factory) | Function | Aftermarket Match | Connection Notes |
|---|---|---|---|
| Yellow | Battery (constant) | Yellow | Fuse mandatory |
| Red | Ignition | Red | Switched 12V |
| Black | Ground | Black | Chassis bolt |
| White/Black stripe | Front left speaker (+) | Gray | 4-8 ohms impedance |
| White | Front left speaker (-) | Gray/Black stripe | Avoid shorting |
Amplifier turn-on leads (usually blue/white) demand special attention. Connect this wire to the aftermarket unit’s corresponding remote output–failure to do so leaves powered subwoofers silent. If retaining factory steering wheel controls, add a resistance-based adapter (e.g., PAC RP4-CH11) between the data bus and the new stereo; OEM steering wheel buttons rely on voltage fluctuations, not CAN signals, in this model.
Speaker wires follow a consistent pattern but check polarity with a 9V battery before finalizing connections–reversing polarity degrades soundstage imaging. Front and rear channels share a common ground in the factory harness, so isolate each pair at the head unit to prevent phase cancellation. For component upgrades, disconnect the OEM tweeters entirely or bypass them via the crossover network to avoid impedance mismatches.
Installation completeness hinges on proper harness routing. Bundle wires with split loom tubing to prevent abrasion against sharp metal edges; secure them with zip ties spaced every 6 inches. Double-check all connections with the ignition off, then test the system incrementally–first power, then illumination, then audio output. If static persists, verify grounds and inspect for fractured wires near the kick panels where the harness bends.
For retainer trim removal, pry the climate control bezel upward from the bottom using a plastic tool–avoid metal pry bars to prevent scratching. The dash retainers clip into slots; apply uniform pressure to release them without breaking tabs. Reinstall trim by aligning the top edge first, then pressing firmly until all clips engage with a distinct snap.
Post-installation, recalibrate the system’s settings. Adjust fade/balance to verify all channels play, then set the equalizer to neutral. If upgrading to a touchscreen, update firmware via USB to resolve compatibility issues with satellite radio or GPS modules. Keep the original removal tool set in the glove compartment for future access.