Taillights, electrical

[Félix]

Hi everyone,

I have had a taillight problem with this Honda Civic 1990.
Changed the bulbs recently and it fixed half of the problem.

When I turn the light switch on, all the lights will go on as they are supposed to. But then when I drive away, the taillights will turn off. The brake lights are working fine, all the time.

What could cause this?

Topic

[alvin]

Check for frayed or corroded wiring between the bulb socket and the light switch. Or the insulation around the wiring may be deteriorated, causing a short circuit to ground. Moisture could be the culprit. Solder the wires together at the faulty point and wrap with electrical tape.

Hope this helps… awm

[dan]

is it blowing a fuse? does it make a difference if you hit any bumps? i wonder if there is a separate ground for the tail lights and brake lights usually the entirety of the tail light assembly shares the same ground.

[JOHN SHORE]

“OPEN” OR “SHORTED CIRCUIT” IF “SHORTED YOU WOULD BE BLOWING FUSE.

JOHN

[Pat61]

Check the light switch. Check it twice if you have DRLs

[Tom]

Ground is good, or there would be no brake lights. Short would lead to bad fuse.

First, I say examine the sockets carefully for corrosion, then, check the headlight switch.

[Lorrin Barth]

If you ever own a boat trailer, a boat trailer you back into the water to launch your boat with, you quickly learn the mysteries of tail lights. The thing is, if water has ever gotten into the light fixtures it will be a battle getting them to work reliably again. Start with new bulbs.

[Félix]

Thanks everyone for the advice.

So I can conclude that there is no short circuit (no blown fuse) and no problem with the ground.
I do have sockets that have moisture and are a bit corroded but like I said the taillights do work before I turn the engine on. The gasket on the left taillight assembly is weak and lets in water (but like I said I changed the bulbs a month ago and all the lights worked except one of the reverse lights.

Is it really relevant to check the headlight switch when the problem is with the taillights? Or is there a taillight switch?

[Cameron]

[quote=”Boisclair” post=107283]

So I can conclude that there is no short circuit (no blown fuse) and no problem with the ground.
I do have sockets that have moisture and are a bit corroded but like I said the taillights do work before I turn the engine on. The gasket on the left taillight assembly is weak and lets in water (but like I said I changed the bulbs a month ago and all the lights worked except one of the reverse lights.

Is it really relevant to check the headlight switch when the problem is with the taillights? Or is there a taillight switch?[/quote]

There is something very amiss with your story here.

You say you hit the light switch in the car and your headlights and tail lights work normally. Then you say when the car is completely stationery and you start the engine the tail lights go out and the headlights remain on.

Sorry but I don’t buy that. There is no relationship between starting the engine and just the tail lights going out.

If you start driving the car away and then you lose the tail lights that is different. There is potentially enough movement and vibration to lose the connection if you have loose and corroded light fittings.

If the fittings are corroded as you say they are then replace them and then re-check. Also get all the water and moisture out of the assemblies that you can and seal up both light assemblies where they are leaking to keep the water out. Don’t just pop in new bulbs into a moist, leaking and corroded fixture and hope all will work out just fine. As others have said, once again check the wiring connections to the back of the fittings.

[Félix]

Haha you are right, my mistake. You say this like I’m trying to lie. It is true that that the lights turn off when I drive away. But would that happen every single time if it was only a matter of vibration?

The wiring looks fine to me but I am no expert.

Also, the driver side taillight only wasn’t sealed properly and took water. The fittings on this side only are corroded. Would that stop the taillight on passenger side (which hasn’t been damaged by water at all) to work?

[Lorrin Barth]

There’s more than one switch: the headlight switch, the brake light switch, the turn signal switches and for the backup lights, the backup light switch.

[Lorrin Barth]

When doing electrical service on you car you need a volt ohm meter or VOM. Anytime a bulb isn’t working, pull it and put your VOM, set to ohms, across the bulb terminals. If ohms reads infinity the bulb is burned out. Next, set the VOM to volts DC and probe the socket for power (the light switch has to be on). If both test okay then it is a bad connection in the socket.

I was working on my nonworking boat trailer lights. I got one side lit and went to the other side to pry the lens off there. That amount of vibration caused the first light to stop working. Once you get that white corrosion around the terminals, you have trouble. Clean them the best you can, make sure you have good spring tension and once the bulb is working, put some grease in the socket to keep out the water.

[Félix]

Ok thanks. My bulbs are new so I don’t think there should be an issue there.

I will clean the corrosion and try again.

So you do not think it is a light switch problem? And if it was, which of the light switches you mentioned control the taillights?

Thanks

[Lorrin Barth]

Old cars used a combination bulb with two filaments. One filament would light when the headlight switch was on. The second filament would light when the brakes were applied. The second filament would also flash when the turn signal was on. If turning and braking at the same time there would only be one brake light showing, the other side would be flashing. So, there you have three different switches working one bulb. To know which switch is bad check which function is missing.

New cars have a separate bulb or bulbs for each function. Taillights are now a design feature of the car and may require multiple bulbs to be pretty.

[Félix]

Yes my car is quite old, a 1990 Honda. Both my taillight and brake light have two filaments.

But how would the corrosion and moisture on one side stop the taillights on the other side from working?

Update : the lights work fine even with engine on, until i release the parking brake

Update 2 : I have found a poster on the internet who notices the same symptoms as me and has fixed the issue by changing his running light relay. Does it make any sense that it would be linked to the handbrake?

[Lorrin Barth]

Well, I finally see what you are talking about. Without having a wiring diagram for a 1990 honda it is impossible for me to know how the engineers wired your car. My wife’s 2004 Subaru has daylight running lights that come on when the car is in motion and this car has a manual transmission – interesting. I have the service manual for it with all the wiring diagrams but since the lights work I’ve never had a reason to look.

The daylight running lights on her car, while dim, apparently look like headlights to her and I’ve seen her leave the house at night with no taillights.

Relays aren’t expensive, you could try one. It is possible to wire anything into the control side of the relay like a parking brake switch. Often you can find another relay in the relay box that is the same and do a swap to see what happens.

[Author]

Replies