2001 LX 4dr 4cyl MT
Is it the multiplex/MICU? I've tried ordering the driver side multiplex, but it's backordered. All other lights are working. My daughter was feeding coins into the CD player, which I suspect may have triggered the issue (all sorts of funny whirring noises and unprompted power cycling on the radio unit).

I found a thread of someone with a similar problem and evidently it wasn't the multiplex in that case, but sadly the OP never reported back with sufficient detail: https://www.hondaaccordforum.com/for...till-op-47991/

 

There is a automatic lights-off relay which controls power to the tail lights, side marker lights, front parking lights, license plate lights, and rear side marker lights. This relay is controlled by MICU, so a faulty MICU is possible fault, but most Accords don't have this feature.

It is also possible for the combination light switch to disable the tail lights.

If you have auto lights off, temporarily you could simply jumper a wire across the relay power path to simulate a closed relay and enable all lights. You will need to find the red/grn - red/blk wires and bridge them across relay contacts. Note, there are two red/grn wires so you will need to figure out which one is suppling 12v through the power bus.

By panel lights do you mean all panel backlighting is gone, but gauges all are working? Again, combination light switch is a common fault for this.

Failure of gauge panel lights and taillights suggests combination light switch problem.

good luck

 

To tell if the Multiplex Control Unit (MCU) located in the driver's side fuse box is bad, see this video. Follow his instructions, if your lights come back on when you do this, the MCU is bad.

 

TexasHonda - Gauges are working, but panel backlighting is not. Thanks for the detailed troubleshooting tips. I've never monkeyed with auto electrical issues beyond replacing fuses, but I have a multimeter and will see what I can figure out.

redbull-1 - Thanks for the link - I'll see if I can isolate the problem as the MICU using the video guide and report back.

Two extremely helpful replies within 12 hours. Much appreciated!

 

If your vanity mirror lights, clock illumination, and glove box light work with the headlight switch on (park or headlights), the combination light switch probably is not the problem.

Additionally, a 2001 Accord LX does not have the automatic light off feature and does not have the taillight relay in the circuit like an EX or 2002.

 

I followed the instructions in the video and the panel backlighting did not turn on. So maybe it's not the MCU? That would be good, because evidently the part is not available.

The only exterior lights working are the headlights, turn signals and brake lights.

The only interior lights working (with or without headlights) are the passenger side spotlight/map light (driver side stopped working several years ago), dome light and courtesy light on bottom of doors. The clock backlight doesn't work, but hasn't for years. The specific indicator lights on the panel DO work, just not the backlighting.

redbull-1 You are correct, my car does not have auto-off lights.

Any further suggestions for troubleshooting?

 

Did you check Fuse No. 10 in the passenger fuse box?

I will have to look at the circuit diagrams to write up some tests for your LX if it is not the fuse. Report back on the fuse and if needed, I will write up something.

The clock is usually just a blown bulb, common issue.

 

If passenger side Fuse 10 is good.

1. Remove the steering wheel plastic cover.
2. With the multimeter/voltmeter, you can test a few wires there to diagnose to narrow down the area of issue(s). You will want to backprobe a few wires. Backprobing is either using a backprobe set or using a thin needle or something and making contact with the metal terminal of the connector without piercing the wire in the back of the still connected connector. Care must be taken to ensure that the wiring does not get damaged. You can use something like a T pin, available at Walmart, etc., and backprobe. These pictures are just to give a picture of the concept of backprobing without piercing any wires.

https://www.hondaaccordforum.com/for...%5D-t-pins-jpg

https://www.hondaaccordforum.com/for...back-probe-jpg

3. At the combination light switch’s 14P gray connector (leave it plugged in):

• With the voltmeter’s black lead touching chassis/body metal ground
• Use the voltmeter’s red lead to backprobe the Red/Grn wire at pin 6

Is there power/voltage at the Red/Grn wire? (Red/Grn wire should be a wire with red color insulation and a green stripe.) -- The Red/Grn wire should have power at all times.

If there is power/voltage at the Red/Grn wire, we move on to backprobe the Red/Blk wire. If there is no power/voltage at the Red/Grn wire at pin 6, the problem is before the light switch.

• With the voltmeter’s black lead touching chassis/body metal ground
• Use the voltmeter’s red lead to backprobe the Red/Blk wire at pin 7

Is there power/voltage at the Red/Blk wire with the headlight switch ON (parking or headlight on)?

If there is voltage at the Red/Blk wire at pin 7, the problem is downstream of the combination light switch. Report back your findings.

 

redbull-1 - many thanks! The passenger side fuse was bad. I replaced it and all lights appear to be working now.

How crazy is it that two shops told us the car had electrical issues and one of them even recommended the MCU replacement? I did remove the radio, which had been malfunctioning due to my daughter force feeding coins into the cd player. I also monkeyed with a bunch of wire harnesses and all of the fuse boxes, so I guess there's a small chance something got jiggled back into place. I guess the moral of the story is don't trust non-specialty shops with auto electrical work...even of the simplest nature.

 

Good to hear it was just the fuse.