Pioneer DEH-S4120BT Audio Receiver Wiring Diagram
Complete diagram
Every cable and connector on the unit and where each one goes.
Terminals and components · 15
- Constant 12 V
- Switched 12 V
- Ground
- System remote
- Illumination and preamp
- Speakers
- AUX input
- Connectors
- Antenna and devices
Caution
Do not let the lead wind around the steering column or shift lever; secure it with clamps.
Hubs
Connection through a USB hub is not supported.
Settings
Turn the AUX setting on in the menu to use it.
Separate screws
The power amp ground and this unit's ground go to the body with different screws. A loose screw can cause smoke, fire or malfunction.
Caution
Do not run it to the battery through the hole into the engine compartment.
Fuse
The rear of the unit has a 10 A fuse: replace it only with one of the same rating.
No ACC position
If the ignition switch has no ACC position, connect it to a terminal that detects the key; otherwise the battery will drain.
Never to a power terminal
Never connect it to the power terminal of an amp or auto antenna: it may drain the battery or cause a malfunction.
Glass antenna
If the vehicle has a glass antenna, connect it to the antenna booster power supply terminal.
Caution
Tape any unused speaker leads. With a two-speaker system, do not connect anything to the spare leads.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Caution
Tape any unused speaker leads. With a two-speaker system, do not connect anything to the spare leads.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Caution
Tape any unused speaker leads. With a two-speaker system, do not connect anything to the spare leads.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Caution
Tape any unused speaker leads. With a two-speaker system, do not connect anything to the spare leads.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Plugs
L = left, R = right; connect with RCA cables (sold separately).
Plugs
L = left, R = right; connect with RCA cables (sold separately).
Subwoofer
The subwoofer output is monaural.
Speaker leads
The eight speaker leads with their polarity, with four speakers or with a subwoofer on the rear leads.
Terminals and components · 4
- Speakers
- Unused
Caution
Tape any unused speaker leads. With a two-speaker system, do not connect anything to the spare leads.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Caution
Tape any unused speaker leads. With a two-speaker system, do not connect anything to the spare leads.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Caution
Tape any unused speaker leads. With a two-speaker system, do not connect anything to the spare leads.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Caution
Tape any unused speaker leads. With a two-speaker system, do not connect anything to the spare leads.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Setting
With a subwoofer on the rear leads, set the rear output to subwoofer (SW) in the menu.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
Setting
With a subwoofer on the rear leads, set the rear output to subwoofer (SW) in the menu.
Negative leads
Do not ground the speaker negative lead or band it together with other speakers' negatives.
2 Ω subwoofer
A 2 Ω subwoofer (or two 4 Ω subwoofers in parallel) goes only to the violet and violet/black leads and must be rated over 70 W. Connect nothing to the green and green/black leads.
Setting
With a subwoofer on the rear leads, set the rear output to subwoofer (SW) in the menu.
2 Ω subwoofer
A 2 Ω subwoofer (or two 4 Ω subwoofers in parallel) goes only to the violet and violet/black leads and must be rated over 70 W. Connect nothing to the green and green/black leads.
Setting
With a subwoofer on the rear leads, set the rear output to subwoofer (SW) in the menu.
External power amp
RCA outputs to the amplifiers and the lead that turns them on.
Terminals and components · 4
- Preamp
- System remote
- Amplifier
Amp turn-on
Connect it to the system remote terminal of each amplifier.
Plugs
L = left, R = right; connect with RCA cables (sold separately).
Plugs
L = left, R = right; connect with RCA cables (sold separately).
Subwoofer
The subwoofer output is monaural.
About This Diagram
These diagrams are redrawn from page 3 of the Pioneer DEH-S4120BT Audio Receiver manual, and we offer them completely free and in English. We have also categorized it in the Car Audio & Stereo (Automotive) section on Diagramverse, and it has been rated by 1 user with an average rating of 5.0. If you have any specific questions about the Pioneer DEH-S4120BT Audio Receiver Wiring Diagram, we suggest checking the Frequently Asked Questions (FAQs) section.
Printable Pioneer DEH-S4120BT Wiring Diagrams
Wiring Instructions
Before you start
The Pioneer DEH-S4120BT receiver works only in vehicles with a 12 V battery and a negative-ground system. It runs on 14.4 V DC nominal, accepts 10.8 V to 15.1 V, and draws up to 10.0 A. A 10 A fuse in the power cord protects it. Do not install it in a 24 V truck or a positive-ground vehicle.
Tools and materials:
- Trim removal tools and screwdrivers
- Wire strippers and crimp connectors, or a vehicle-specific harness adapter (sold separately)
- A digital multimeter
- Electrical tape, cable clamps and ties
- RCA cables if you are adding an amplifier
The unit's harness leads are already sized for its current, so never shorten them. The sources don't give a wire gauge for speaker extensions or amplifier runs. Use good-quality stranded copper wire and follow your amplifier maker's gauge chart.
Pioneer recommends installation by someone trained in automotive electronics. If the job means drilling holes or modifying the vehicle, ask your dealer or a professional installer first. Before you touch any wiring, disconnect the battery negative terminal.
Pick the tab that matches your system. Complete shows every connection. Speakers has four variants: Four speakers, 4 Ω subwoofers, 2 Ω subwoofer and Two 4 Ω in parallel. Use Power amp if you are feeding external amplifiers from the RCA outputs.
Step-by-step wiring
- With the battery disconnected, identify the vehicle-side wires. You will need a constant 12 V feed, an ignition-switched 12 V feed, a ground point, and the four speaker pairs. A harness adapter saves you from cutting factory wiring.
- Connect Black first. Bolt it to clean, paint-free body metal. If you are adding an amplifier, give the amp's ground its own screw, separate from this unit's ground. A loose ground screw can cause smoke, fire or a malfunction.
- Connect Yellow to the constant 12 V supply terminal. Do not run it through the firewall straight to the battery. Never cut into the power cord's insulation to share power with other devices.
- Connect Red to the terminal controlled by the ignition switch. If your ignition switch has no ACC position, use a terminal that detects ignition key operation. Otherwise the unit can drain the battery.
- Wire the speakers for your variant. Four speakers: connect FL, FR, RL and RR, with each plain color to + and its black-striped partner to −. 4 Ω subwoofers: connect a 4 Ω subwoofer to the green pair and another to the violet pair. 2 Ω subwoofer or Two 4 Ω in parallel: use only Violet and Violet/black, then tape the green and green/black leads separately. Never connect a speaker negative to ground, and never join the negative leads of several speakers.
- Connect Blue/white to the amplifier's system remote terminal or the auto-antenna relay control terminal (300 mA max, 12 V DC). With a glass antenna, connect it to the antenna booster's power supply terminal instead. Never connect it to the power terminal of an amp or a power antenna. If you don't use it, tape it.
- For amplifiers, run RCA cables from FRONT OUT to the front amp and from REAR/SUB OUT to the rear or subwoofer amp. On this model the preamp outputs deliver up to 4.0 V, so start with the amp's input gain low.
- Plug the vehicle antenna into ANT. Route the MIC lead to the sun visor or steering column, keeping it clear of the steering column and shift lever. Connect a steering-wheel adapter to REMOTE if you have one.
- Cover every unused connector with insulating tape. Clamp the wiring away from seat rails, the shift lever and heater outlets, and tape any wire that touches metal. Leave room behind the chassis so air can flow, and mount the unit at less than 60° from horizontal.
Testing and start-up
Before sliding the unit fully into the dash, reconnect the battery and take these measurements:
- Yellow: about 12 V with the key off.
- Red: 0 V with the key off, and about 12 V with the key at ACC or ON.
- Ground: close to 0 Ω between Black and bare chassis metal.
Remove the front panel and press RESET with a pointed tool longer than 8 mm. Turn the ignition ON. The setup menu should appear: set the language and clock.
Next, open the INITIAL settings:
- Set REAR-SP to FUL for full-range rear speakers, or SW for a subwoofer wired straight to the rear leads.
- Set SP-P/O MODE to match what is connected to the RCA output.
- If you have a subwoofer, turn SUBWOOFER ON in the AUDIO settings.
Then check the system:
- Use BALANCE and FADER to confirm that each speaker plays from the correct corner.
- Confirm that any amplifier and power antenna switch on and off with the unit.
- Make a test call to check the microphone.
Safety notes
- Twelve volts won't give you a dangerous shock, but a short circuit can push enough current to melt wiring and start a fire. Keep the battery disconnected until the wiring is finished. If the fuse blows, replace it only with the same 10 A rating.
- Use speakers rated over 50 W at 4 to 8 Ω. Never use 1 to 3 Ω loads, except a 2 Ω subwoofer on the violet leads, which must be rated over 70 W.
- As general good practice, stay clear of airbag wiring and connectors behind the dash.
- Leaving the unit on Bluetooth standby with the engine off can drain the battery.
Troubleshooting
| Symptom | Probable Cause | What to Check |
|---|---|---|
| The unit is completely dead and the display never lights | Blown 10 A fuse, no 12 V on Yellow or Red, or a bad chassis ground | Check the fuse in the power cord. Measure about 12 V on Yellow with the key off and on Red with the key at ACC or ON. Measure close to 0 Ω from Black to bare metal. |
| The clock and presets reset every time I turn off the car | Yellow and Red swapped, or Yellow connected to a switched feed | With the key off, Yellow should read about 12 V and Red 0 V. Swap the leads or move Yellow to a true constant 12 V terminal. |
| The battery goes flat after the car sits overnight | Red on a constant feed, Blue/white on an amp power terminal, or Bluetooth left on standby | With the key off, Red must read 0 V. Make sure Blue/white goes only to the amp's system remote terminal, never its power terminal. |
| The display shows AMP ERROR and there's no sound | A speaker lead shorted to the body, negatives grounded or joined together, or too low an impedance | Unplug the speakers and check each pair: it must not read 0 Ω, and neither lead should have continuity to chassis. Separate any joined negatives, then turn the ignition off and back on. |
| The sound is thin with weak bass, especially between the doors | One speaker wired with reversed polarity | Confirm each plain color goes to + and its black-striped partner to −. For example, White to + and White/black to − on FL. |
| The rear-wired subwoofer plays full-range music, or the fader is missing | The REAR-SP setting doesn't match the wiring | Set REAR-SP to SW for a subwoofer wired straight to the rear leads, or FUL for full-range rear speakers. Turn SUBWOOFER ON in the AUDIO settings. |
| A 2 Ω subwoofer distorts or triggers AMP ERROR | It is connected to the green pair, or the green leads are touching something | Move it to Violet and Violet/black only, and tape Green and Green/black separately. Make sure the subwoofer is rated over 70 W. |
| The external amplifier never turns on | Blue/white not connected, or connected to the wrong amp terminal | With the unit on, measure about 12 V at the amp's remote terminal. If several devices share Blue/white and draw more than 300 mA, add a relay. |
| The amplified speakers distort even at moderate volume | Amp gain set too high for this unit's 4.0 V preamp output, or the amp sharing this unit's ground screw | Turn the amp's input gain down and raise it slowly. Give the amp its own ground screw on bare metal. |
| Radio reception is poor, or the power antenna doesn't extend | Antenna plug not fully seated in ANT, or Blue/white not connected to the antenna relay or booster | Reseat the antenna plug. With the unit on, measure about 12 V on Blue/white at the relay control or booster terminal. |
| Callers say they can't hear me | Microphone not plugged in, placed too far away, or blocked by a lowered sun visor | Check that the MIC plug is fully seated in the unit. Move the microphone in front of the driver or onto the steering column. |
| The display shows CHECK USB | A shorted USB cable, or a device drawing more than the 1.5 A limit | Check the cable for pinching or damage. Disconnect the device, turn the ignition off and back on, and connect only compliant devices. |
