If you're having trouble getting your DCI to work, this is NOT the place to start.  Go back to the DCI Help page for basic troubleshooting, then come back here if you are still having trouble.

If, however, you have "been there, done that" and are looking to do some serious troubleshooting (like with tools) read on.  The information on this page is for experienced installers or owners with a good understanding of automobile wiring and/or electronics. 

Tools you should have available:

I'll break this page into three sections; one for troubleshooting procedures common to both types of DCI, one for the Wired DCIs, and a third for the IR DCI.  The only wiring difference between the Wired DCIs and the IR DCI is the Wired versions have a 3.5mm stereo plug in place of the IR emitter.
 

Troubleshooting Common to all DCI's

Basic power and wiring tests

Verify correct voltage (nominal 12vdc) on the DCI red wire when the ignition switch is in either the ACC or ON positions.

Make sure the DCI has a good ground by measuring 12vdc from the black wire to the red wire with the ignition switch in either the ACC or ON position.

The DCI draws about 12ma (0.012 amps) when powered up and idle, so if you measure the current by inserting an ammeter in series with the DCI red wire that will give you a good idea if it's working.  If the reading is near 0ma, either you don't have power or the DCI is bad.  If it's more than 20ma, make sure no dash buttons are pressed, as the IR DCI will consume a few hundred milliamps when transmitting IR commands. 

Wired Mute functionality (the DCI blue wire)

The DCI inverts the dash mute switch signal, turning the +12v from the dash mute circuit into a ground on the blue wire.  Your HU will go into MUTE or INTERRUPT mode when it sees that ground (assuming your HU has a wired mute input that is connected to the DCI blue wire).

Without a meter - First, verify your HU mutes when you ground it's ATT or MUTE wire, un-mutes when it's not grounded.  If not, you've got the wrong wire or the HU is bad.  If it does mute, then try disconnecting the DCI purple wire from the dash mute wiring.  With accessory power ON, apply +12v to the purple wire.  The HU should go into MUTE or INTERRUPT.  Removing +12v from the purple wire should make the HU un-mute.  If it does not, the DCI is bad.

With a meter - If the above test works but you still can't control mute from the dash controls you'll need to use a meter.  The factory mute circuit provides +12v to the DCI purple wire when mute is ON and an open circuit when OFF.   Verify you read +12v on the DCI purple wire when the dash mute green LED is lit, and less than 1v when the LED is off.  If not, disconnect the DCI purple wire from the factory mute wire and check the factory mute wire again.  If you get the correct readings, the DCI may be bad.  If you have +12v all the time or never get +12v, the dash mute circuit is bad.

If the voltages on the DCI purple wire check out, verify the voltages on the DCI blue wire.  They should essentially be the opposite of the purple wire.

Dash Switch Wiring:

The dash switches on the S2000 provide a different resistance to ground for each button pressed and to make sure the dash circuitry is working you can perform these tests.  Measure the voltage on the DCI green wire with the DCI connected and the ignition ON, but when measuring resistance (Dash Switch wire wire to ground) turn off the ignition and unplug the DCI.  These readings can be off by 10% and the DCI will still work.

Notice that the "Volume Down" button operates at .22 volts, which is very close to ground (0 volts).  The DCI will interpret a ground as a Volume Down command, so a good troubleshooting test to make is to disconnect the Dash Switch wire from the DCI GREEN wire and ground the DCI GREEN wire.  The DCI should send continuous Volume Down commands.  If it doesn't, then check the "output" of the DCI - poor positioning of the IR emitter or a bad IR emitter, or an improperly seated 3.5mm plug on a wired DCI.  If they look right it could be a bad DCI.

SCV wiring (Speed-Controlled Volume)

The DCI gray wire can be connected to the vehicle speed signal at the Convertible Top Module to provide automatic volume adjustments as speed increases and decreases.  If SCV is not working, review the operating instructions to make sure it has not been disabled by user programming. 

If it still does not work, you should check the vehicle speed signal wire for a DC voltage that alternates from 5v to ground about 4 times a second for every 1mph of vehicle speed.  This signal is too fast to be read by a digital voltmeter if the vehicle is at speed, though an analog meter will usually read about 2.5 volts because of it's ability to 'average' out an alternating signal.

You can also roll the vehicle slowly (or by hand) and see the voltage change from ground to 5v several times per revolution of the wheels.  If this signal is not seen on your meter check for good connections at both the DCI and the Convertible Top Module.  It is unlikely the signal is not present on the factory harness since it is used for other circuits in the car and the ECM would be generating a CEL if it was missing.

IR DCI Troubleshooting

Measure current draw - The DCI draws about 12ma (0.012 amps) when powered up and idle, so if you measure the current by inserting an ammeter in series with the DCI red wire that will give you a good idea if it's working.  If the reading is near 0ma, either you don't have power or the DCI is bad.  If it's more than 20 or 25ma, make sure no dash buttons are pressed, as the IR DCI will consume a few hundred milliamps when transmitting IR commands.  That's another test you can make while your ammeter is in place - press each dash button and make sure you see the current increase as each IR command is transmitted.  Bear in mind some dash switches (MODE & CH) only transmit for a short burst when released.  The VOLUME buttons transmit instantly when pressed and will auto-repeat if held down so you should see current spikes repeat if you hold the button.

Verify IR emitter works - The IR emitter is an infra-red LED.  You can substitute almost any IR LED (like from Radio Shack) if you suspect the IR emitter to be bad.  The emitter wire may not be color-coded so trace it back to the DCI module to identify the positive and negative leads.  The LED wire next to the BLACK DCI wire is positive (anode of the LED), the LED wire next to the GRAY DCI wire is negative (cathode).

You can use a commercially-available IR test tool to check for IR emissions from the LED.  These tools are small plastic wands with an IR-sensitive coating that glows when subjected to intense IR light.  Radio Shack used to sell them but they may be available at local electronic shops too.

If you have a video camcorder, digital camera, or cell phone with a digital camera you might consider using it to verify the IR emitter is working.  Infra-red light is invisible to human eyes but is often 'seen' by the CCD imagers used in cameras.  If you have a camera, point it at the IR emitter and watch (through the camera viewfinder) as you press a dash switch.  If the IR emitter is working you should see a momentary flash of light coming the IR emitter when viewed through the camera viewfinder.  If you do, then you know the IR emitter is working, so double-check your dip switches.  If you get no flash of light you may have a bad IR emitter, and you should contact me for assistance.  You can verify your camera can see IR light by pointing any remote control at it and pressing a button - you will see a flash of light on the "business end" of the remote control.

Wired DCI Troubleshooting

Measure current draw - The DCI draws about 12ma (0.012 amps)  when powered up and idle, so if you measure the current by inserting an ammeter in series with the DCI red wire that will give you a good idea if it's working.  If the reading is near 0ma, either you don't have power or the DCI is bad.  Current readings above 20ma usually indicate a bad DCI.

On Sony head units you have to be careful how you plug the 3.5mm stereo connector into the back of the head unit.  It's easy to get it "almost seated" and that causes all kinds of problems with the DCI - from nothing working to intermittent functions and strange behavior.  On the Sony head unit's I've seen there is a metal boss around the jack and if your DCI has a right-angle plug it only fits correctly in one position - with the wire facing up.  So double-check the plug if you have a Sony head unit.

There's not much more you can do to troubleshoot a wired DCI.  You can't measure the output on the stereo plug because the readings aren't valid unless it's plugged into the head unit, which means you can't measure it without cutting into the cable, which is not recommended.