2003 Honda CRV



January, 6, 2010 AT 6:50 AM

Electrical problem
2003 Honda CRV 4 cyl Four Wheel Drive Automatic 115000 miles

My 2003 Cr-V has stopped chiming when I open the door and forget my headlights on.

Yesterday I drained my battery because I am so used to this chime telling me that the lights are on.

How do I fix/diagnose what the problem?

Note that the dome light still works. So am not sure if this is the door switch or not that is the problem? Is the chime and dome light on same switch?


10 Answers



January, 6, 2010 AT 11:32 AM

Hi JohnnyBMe,

The door and dome light switch are the same for iindicating when the door is open. The dome light has an additional switch that can operate to over ride the door switch.

If the dome light is working with the doors being opened, then the door switch is not the cause of the peoblem.

The other likely cause would be the key in switch. It is located on the key cylinder and not operating to inform the system that the ignition key has been turned off.

Another possibility is a faulty integrated control relay plugged into the under dash fuse box.



January, 6, 2010 AT 2:01 PM

Thanks for your reply KHLow2008,

I guess the only one I can look into repairing myself would be the relay? The key cylinder would be a mechanic thing for sure? How would I look for a relay? Ie. How would I call it exactly?



January, 7, 2010 AT 11:28 AM

Sorry for a mistake made in my earlier reply. The integrated control relay is for an older version and for your model it is known as Multiplex Control Syatem.

All the problem listed falls under this control system.

Here is a description of the system.


The multiplex control system has four internal functions:
" Multiplexing (send multiple signals over shared wires)
" Wake up/sleep (runs at full power only on demand to reduce battery draw)
" Fail-safe (fixes or ignores faulty signals)
" Self-diagnosis (Mode 1 for system DTCs, Mode 2 for input lines)

The system controls the function of these circuits:
" Entry light control (ignition key light and ceiling light)
" Wiper/washer (intermittent wipe and park functions)
" Interlock system
" Keyless/power door lock
" Gauge assembly, temperature gauge, and indicator lights
" HVAC (Compressor and fan control)
" Key-in reminder
" Lights-on reminder
" Seat belt reminder


To reduce the number of wire harnesses, digital signals are sent via shared multiplex communication lines rather than sending normal electrical signals through individual wires.

" The input signals from each switch are converted to digital signals at the central processing unit (CPU).
" The digital signals are sent from the transmitting unit to the receiving unit as serial signals.
" The transmitted signal is converted to a switch signal at the receiving unit, and it operates the related component or monitors a switch.
" There are exclusive communication lines between the ECM/PCM, the gauge assembly, the keyless receiver unit, and the under-dash fuse/relay box.


The multiplex control system has "wake-up" and "sleep" functions to decrease parasitic draw on the battery when the ignition switch is OFF.

" In the sleep mode, the multiplex control unit stops functioning (communication and CPU control) when it is not necessary for the system to operate.
" As soon as any operation is requested (for example, a door is unlocked), the related control unit in the sleep mode immediately wakes up and begins to function.
" When the ignition switch is turned OFF, and the driver's or front passenger's door is opened, then closed, there is about a 40 second delay before the control unit goes from the wake-up mode to the sleep mode.
" If any door is open, the sleep mode will not function.
" If a key is in the ignition switch, the sleep mode will not function.
" When in sleep mode, the draw is reduced from 70-80 mA to less than 10 mA.


To prevent improper operation, the multiplex control system has a fail-safe function. In the fail-safe mode, the output signal is fixed when any part of the system malfunctions (for example, a faulty control unit or communication line).

Each control unit has a hardware fail-safe function that fixes the output signal when there is any CPU malfunction, and a software fail-safe function that ignores the signal from the malfunctioning control unit and allows the system to operate normally.

Check the # 9 fuse in underdash fuse box. Replace it if it is blown.

Diagnostics can be done with the aid of a special tools which can be fabricated, it is a jumper wire as shown in diagram.

Get the jumper ready and I will send you the diagnostic procedures.



January, 13, 2010 AT 7:00 AM

Upon further investigation. It actually is the door switch I think. The dome light trigger for the driver door does not work as I thought. I didn't test it correctly at first.

I think it is busted. The one on the passenger side is more firm. The driver switch is very soft. So probably broken.

. Do have/know of instructions to replace this switch.



January, 13, 2010 AT 7:13 AM

Yes, a faulty door switch would cause the problem.

I am not sure which tyoe of switch is used for your vehicle but for most Honda door switches, push the moveable tab and you would notice a crossed head screw.

Remove the screw and the switch can be pulled out, it is slotted in, behind which you would see a wire coupler. Disconnect the coper and the switch can be replaced.



January, 13, 2010 AT 8:03 AM

Mine seems to be behind a rubber cover. No tab. But I guess it should be simple enough.

. Thanks for your great help.



January, 13, 2010 AT 8:08 AM

You are welcomed.

Yes, it is rather simple. The rubber cover can be removed by pulling at the edges and you would see the holding screw after removal.



January, 15, 2010 AT 11:52 AM

Well, what do you know? Every once in a while a get a little bit of luck on my side.

. Before I went out to actually purchase the part, I went and checked it first. It ended up being that the darn switch came off the metal holder that is fastened to the rubber cover. I just snapped it back in and presto! It works again. Saved myself about $15CDN.

Thanks again.



January, 15, 2010 AT 12:18 PM

You are welcomed and it must have been your lucky day.

Thanks for the input.



October, 27, 2013 AT 8:32 AM


I hope you are still available to give instructions on how to use the Mode 1, Mode 2 and Fail Safe mode for the MCU. I would sure like to prove it is the problem before I replace it.


02 Civic

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