Complete 2006 Scion xB Stereo Wiring Harness Diagram Guide
Locate the harness connector behind the factory radio unit–it’s the 24-pin white plug labeled “17” on section A-12 of the official repair manual. Pin 1 (constant 12V) runs through a red wire with a 10A fuse at position 14 in the under-dash fuse box. Pin 4 (switched 12V) uses a yellow wire, toggled by the ignition. Ground (pin 8) is a black wire secured to chassis point G302, near the driver’s side kick panel. Speakers follow a balanced pair layout: front-left tweeter (pins 2 & 3, light blue/white), rear-left full-range (pins 6 & 7, gray/red), front-right tweeter (pins 10 & 11, green/white), rear-right full-range (pins 16 & 17, violet/yellow).
For aftermarket upgrades, splice the new head unit’s harness to the adapter kit Metra 70-8114. Match the red wire to pin 1, yellow to pin 4, black to pin 8. Speaker outputs require 4Ω impedance–any mismatch risks amplifier overload. If retaining the stock amplifier (behind the glove box), preserve pins 9 (data bus), 12 (amp turn-on), and 18 (illumination). Cutting these will trigger a “no sound” error code in the vehicle’s ECU. Use a multimeter to verify continuity before powering on; voltage drops below 11.5V indicate corroded connectors or a blown fuse.
Installation errors often trace to reversed polarity or loose grounds. Check for stray strands when crimping connectors–even a single frayed filament can cause radio static or intermittent failure. If the display dims unpredictably, inspect pin 18 (orange/black wire) for a faulty dimmer relay. For navigation systems, wire the GPS antenna (blue connector, pin 1) directly to the retrofit module, bypassing the factory amp’s filtering circuit. Always disconnect the negative terminal before handling any unshielded wires to prevent shorting the CAN bus.
Refer to the official repair DVD (region-specific: RM1085E for North America) for torque specs on fascia screws. The upper dash trim snaps require 8-10 in-lbs; overtightening cracks the brittle plastic. Remove the HVAC controls by depressing the release tabs at the bottom edge–no tools needed. For low-profile amplifiers, relocate the stock unit to the rear seat base plate using the existing mounting holes. Test all connections with a 1KHz sine wave before finalizing the dashboard reassembly.
Complete Aftermarket Audio System Integration for the First-Gen xB
Locate the factory harness behind the dash cluster near the driver’s knee bolster–use a 12V test light to confirm constant power on the yellow wire (memory keep-alive) and switched ignition on the red wire before splicing. Metra 70-8114 adapter plate simplifies aftermarket head-unit mounting without trimming the original dash brackets; secure with the included self-tapping screws angled away from HVAC ducts.
Harness Pinout Reference
| Factory Wire Color | Function | Aftermarket Connection | Wire Gauge |
|---|---|---|---|
| Yellow (YEL) | Battery constant | 10A fused lead | 18 AWG |
| Red (RED) | Ignition switched | Main power input | 18 AWG |
| Black (BLK) | Ground | Chassis bolt or dedicated ring terminal | 14 AWG |
| Blue/White (BLU/WHT) | Antenna motor | Power antenna trigger | 20 AWG |
| Gray (GRY) x2 | Front left/right (+) | 4-channel speaker input | 22 AWG |
| White/Black (WHT/BLK) x2 | Front left/right (-) | Speaker negative | 22 AWG |
Route RCA cables from the head-unit to the amplifier under the driver’s seat; avoid parallel runs with any OEM data buses to prevent signal noise. Crutchfield wiring harness CR-4 matches the rear speaker harness–pin 1 (BLK/RED) and pin 2 (GRN/YEL) carry rear fill signals; verify with a multimeter for 4-ohm load before finalizing connections.
Finalize grounding at the seat track bolt under the driver’s seat–clean paint with a wire brush, apply dielectric grease, and torque to 9 Nm. Test all four channels individually at low volume before reassembling trim panels to confirm phase alignment; rear fill will drop out if polarity is reversed.
Finding the OEM Electrical Connector for the 2006 xB Hatchback
Start by removing the lower dashboard panel beneath the steering column–two 10mm bolts secure it; set them aside on a magnetic tray. Behind the panel, the main factory harness appears as a 24-pin black connector with a rectangular latch; it’s bundled alongside a smaller 6-pin climate control plug. Trace the wires: the larger connector’s pins 1–10 carry constant power (yellow, 12AWG), pins 11–18 handle speaker outputs (striped pairs), and pins 19–24 manage illumination (orange/white). Label each bundle with masking tape before unplugging.
If the connector isn’t visible, slide your hand upward behind the radio pocket–feel for a rigid horizontal beam; the harness is clipped to its underside. Disconnect the battery negative terminal first to prevent shorts; the connector’s latch requires firm downward pressure while wiggling it free. Check for corrosion on the terminals; clean with electrical contact spray if resistance exceeds 0.1 ohms.
For alternative access, remove the driver-side kick panel–one Phillips screw holds it, revealing the chassis loom entry point. Follow the loom upward until it converges with the main dash harness; the OEM plug’s distinctive latch confirms identification. Use a multimeter to verify +12V on yellow wires (ignition-on) and ground on bare copper strands before splicing aftermarket adapters.
Color-Coded Wire Identification for Aftermarket Head Unit Installation
Locate the yellow 12V constant wire first–it supplies power directly from the battery to retain settings. This wire is typically bundled with the main harness behind the factory radio chassis. Verify continuity with a multimeter before connecting it to the aftermarket unit’s memorized accessory lead. Failure to identify this wire correctly will result in reset clock and preset loss after ignition cycles.
Pair the red ignition-switched wire to the vehicle’s ACC or RUN circuit. On most compact hatchbacks from this era, this wire connects to a fuse tap on the interior distribution box (F8 or F12, depending on trim). Avoid splicing into the orange illumination lead–this wire only powers the dimmer circuit and will not activate the new unit when the key is turned.
Ground the black chassis wire to a bare metal point near the dash reinforcement bracket. Sand the mounting surface down to unpainted steel for a low-resistance path. Poor grounding causes audio distortion, intermittent shutdowns, and parasitic battery drain detectable after 24 hours of inactivity. Use a crimp ring terminal and a 10mm bolt fortified with dielectric grease to prevent corrosion.
Speaker Connections by Factory Color Codes:
- Front Left (+): Gray (solid stripe) and gray/black (striped) – join to the aftermarket unit’s FL (+) and FL (-) respectively.
- Front Right (+): White (solid stripe) and white/black (striped) – connect to FR (+) and FR (-).
- Rear Left (+): Green (solid stripe) and green/black (striped) – wire to RL (+) and RL (-).
- Rear Right (+): Purple (solid stripe) and purple/black (striped) – attach to RR (+) and RR (-).
Isolate the blue/white remote turn-on lead. This wire activates external amplifiers when the new unit powers up. Incorrect connection here can overload the fuse block, damaging both the amplifier and head unit microcontroller. Use a 5-amp inline fuse between the remote lead and any external accessory to prevent backfeed.
Match the pink RCA or high-level speaker inputs if retrofitting an amplifier. Rear channels often require a separate harness adapter (Metra 70-8113 or equivalent) due to factory implementation of balanced differential outputs. Validate impedance of each speaker load at 4 ohms–any deviation suggests a shorted voice coil or incorrect polarity at the original connector.
Test each circuit sequentially before securing the head unit into the dash frame. Power on the ignition, engage the new interface, and confirm all channels output audio through pink noise or a 1kHz sine wave. Scan for DC offset on speaker leads immediately after; readings above 50mV indicate a damaged output stage requiring recalibration.
Step-by-Step Power and Ground Wire Connection Process
Locate the vehicle’s fuse box under the dashboard–driver’s side for most compact models. Identify an unused 10A or 15A fuse slot; a multimeter set to DC voltage will confirm live power when probe tips touch the fuse terminals. Crimp a 16-gauge red wire to a mini fuse tap, ensuring the metal blade aligns with the fuse’s lower contact. Insert the tap into the selected slot, then route the wire through the firewall grommet near the pedal assembly, using a 3/32″ stiff wire to guide it if necessary.
Securing the Ground Connection
Strip 1/2″ of insulation from a 14-gauge black wire. Attach a ring terminal, then bolt it to a bare metal spot behind the kick panel–avoid painted surfaces. Sand the contact point to bare steel with 80-grit paper, then apply dielectric grease to prevent corrosion. Tighten the bolt to 8-10 lb-ft torque; loose grounds cause 120Hz alternator whine.
Test the power lead with a 12V test light before final connection. Connect the red wire to the deck’s “B+” terminal, then the ground to the chassis stud marked “GND.” Avoid splices near moving pedals or heat sources like exhaust tunnels. If the audio unit powers down after key-off, swap the fuse tap to a constant 12V source, typically labeled “BAT” or “MEM.”
Insulate all connections with adhesive-lined heat shrink tubing (3:1 ratio) or liquid electrical tape. Route wires parallel to existing harnesses, using zip ties every 6 inches to prevent rattles or chafing. Verify no exposed copper touches metal edges within the door jamb or seat rail paths. A final voltage check at the harness plug should read 11.8-12.6V with engine off, 13.2-14.8V running.
Troubleshooting Voltage Drops
If dimming occurs with bass hits, upgrade to 12-gauge power and ground wires. Test voltage drop across the ground path with the engine at 2000 RPM–ideal reading is under 0.2V. For persistent noise, add a 1000uF capacitor in-line near the amplifier’s power input, mounted to the vehicle’s chassis. Avoid twisting power and speaker wires together; maintain 6″ separation to prevent RF interference.