Okay, I've gotta weird problem with my 1998 Outback. It happened after I was towing a trailer, but not sure what's going on. Even when I have no lights on, the left turn signal on the trailer stays on, not blinking, just on.

 

When I disconnected the tow wiring harness there's a problem with the car turn signal, same side. The symptoms are whenever I apply the brakes, my left hand turn signal stops lighting. When I release, it comes back on as normal. Can anybody help me fix this?

 

Thanks... Jon

Sounds as if it is grounding when the brakes are applied causing it to stop blinking.Go back over your wires and check them.

Okay, I've gotta weird problem with my 1998 Outback. It happened after I was towing a trailer, but not sure what's going on. Even when I have no lights on, the left turn signal on the trailer stays on, not blinking, just on.

 

When I disconnected the tow wiring harness there's a problem with the car turn signal, same side. The symptoms are whenever I apply the brakes, my left hand turn signal stops lighting. When I release, it comes back on as normal. Can anybody help me fix this?

 

Thanks... Jon

 

Ok this is odd

the turn signals and brake lights are normally independent circuits on the car. Unless you have an electronic black box for the trailer lights to convert the two wire system to a one wire system, you are getting a back feed thru the trailer connector somehow.

 

My bet is its in th trailer harness connector.

 

Did the trailer have one lense for turn/brake or two.

 

nipper

The brake and turn signals are "switched" in the trailer light adapter box with diodes.

 

If one of the diodes is shorted, it will cause this problem.

BINGO!

 

 

nipper

Ok this is odd

the turn signals and brake lights are normally independent circuits on the car. Unless you have an electronic black box for the trailer lights to convert the two wire system to a one wire system, you are getting a back feed thru the trailer connector somehow.

 

My bet is its in th trailer harness connector.

 

Did the trailer have one lense for turn/brake or two.

 

nipper

 

Yes I did buy a box that plugs into a wiring harness in the back to power the trailer lights. But, it's disconnected now and still getting the brake/turn signal weirdities.

 

The trailer has one lens for turn/brake on each side.

 

...Jon

The brake and turn signals are "switched" in the trailer light adapter box with diodes.

 

If one of the diodes is shorted, it will cause this problem.

 

Even after the adaptor box is unplugged?

Sounds as if it is grounding when the brakes are applied causing it to stop blinking.Go back over your wires and check them.

 

Hmmm, so you're saying look for where the wire insulation may be compormised exposing the wire?

Lets start by removing the turn signal bulb, then try the brakes with the turn signal on, then do it the other way. Make sure they work. im still suspecing the harness for the trailer wiring i dont know how your harness is wired in the car, can it be removed? Some of them just plug into the existing harness, some are hard wired.

 

nipper

I would recommend you check the flasher unit. Something may have damaged it. If that is ok then check the grounding to the light for a problem.

Yea. ditto on what Cougar said since you disconnected the box. If there is no ground present for a lamp circuit, it will find another path if it's there, through a bulb.

certain bulbs are dual filament and if one 'droops' or breaks and then touches the other filament, you can get some weird lighting issues. I dunno.

I would recommend you check the flasher unit. Something may have damaged it. If that is ok then check the grounding to the light for a problem.

 

Hey Glen, thanks for the tip. I'm new, but I'll catch on quick... How do I test the flasher unit? Is that a plug in module or ...?

Lets start by removing the turn signal bulb, then try the brakes with the turn signal on, then do it the other way. Make sure they work. im still suspecing the harness for the trailer wiring i dont know how your harness is wired in the car, can it be removed? Some of them just plug into the existing harness, some are hard wired.

 

nipper

The bulbs work fine. What happens is when I flip the turn signal on, the lights start flashing as normal that is until I depress the brake pedal. That stops the lights and I notice the arrow indicator in the instrument cluster dims. When I release the pedal, all back to normal.

 

The trailer wiring harness is a little black box which, as you mention, plugs into a connector at the rear of the Sube's p-side tail light. This is the same side I'm having the problem with, even though I have disconnected the little black box.

hrmm

The brake lights and the turn signals are two toatally independent circuits which do not cross over anywhere, except maybe the at the ground. The brake lamps are dual filamint as they carry both the parking lamps and the brake lamps.

This is going to be laborous to do, but remove the brake light bulbs, then check to see if the turn signals work as they should, and re-creat the conditions. It could be you have a bad socket, or bad bulb feeding back through the ground.

This is very hard to diagnose without seeing it in person.

 

nipper

The module does plug-in and is usually under the dash near the driver's feet. You may be able to locate it by listening to the clicking with the blinker on. To test it you will either have to replace it or check the voltage on the left side output of the module with the left blinker and brake on. If the output doesn't pulse then it would seem the flasher is not working correctly.

 

Hey Glen, thanks for the tip. I'm new, but I'll catch on quick... How do I test the flasher unit? Is that a plug in module or ...?

I think the two circuits do tie together through the turn switch and flasher. The two circuits share the same bulb filament. When the brake is pressed there is a continous voltage sent to the rear lights, as you know. When the turn signal is on at the same time, there needs to be a way to remove the brake light signal to turn the light off and indicate the turn. This is done through the flasher and turn signal switch.

 

Not too long ago a friend of mine had intermittent trouble with his van's left rear brake light not working. At first we thought it was something with the light but it was ok. The problem turned out to be in the turn indictor switch. If it was not centered in the off position correctly the left brake light wouldn't work. The switch was worn due to age and use.

 

hrmm

The brake lights and the turn signals are two toatally independent circuits which do not cross over anywhere, except maybe the at the ground. The brake lamps are dual filamint as they carry both the parking lamps and the brake lamps.

 

nipper

they dont tie together when you have amber turn signals, as there is no need for them too. the turn signals are singal filament bulbs

 

When you have no amber signals, the odds are they tie in thru the turn signal switch, If he did not have amber signals (and i have the same car he does only 1 year older) i would suggest a bad turn signal switch.

The haynes manual shows (just as i explained) no cross over between the brake lights and the turn signals, but they do share a common ground.

So we are looking at a possible backfeed again.

 

nipper

Good point Nipper. I forgot about the newer style of lights being different.

Check for a good ground on both the turn signal and brake light on the respective connectors.

 

Since you fiddled with the connector back there, I would take a good look around that area.

 

If you take the brake bulb out, what does it do?

Tiny Clark,

 

After reading your post I am wondering if you suspect the turn indicator light is finding a ground through the brake light bulb. Perhaps there is a problem with the turn signal ground.

This is kinda like one of those weird wiring problems we experience on our C130's from time to time, very strange, but there has to be a simple (or not-so-simple, depends on how you look at it) answer.

 

It's usually my job to find it, and I usually bat around .995. Of course, when you've been doing it for over 30 years , it helps...

I suppose you've already tried to narrow down the problem by placing it in failure mode and pulling/pushing/twisting/thumping all the areas of interest? (cables,bulbs,connectors,etc.)

 

 

If there were no change detected doing the above, I would strongly suspect the trailer wiring 'black box'.

I have to think that the turn signal light has lost it's ground and is somehow finding a ground through the brake light filament (possibly with the new harness wiring). When power is then applied to the brake light the turn signal has power applied to each side of it and so it turns off until the brake is released.

 

It would seem also that there must be a wiring error with the new wiring.

Okay, I've gotta weird problem with my 1998 Outback. It happened after I was towing a trailer, but not sure what's going on. Even when I have no lights on, the left turn signal on the trailer stays on, not blinking, just on.

 

When I disconnected the tow wiring harness there's a problem with the car turn signal, same side. The symptoms are whenever I apply the brakes, my left hand turn signal stops lighting. When I release, it comes back on as normal. Can anybody help me fix this?

 

Thanks... Jon

 

SO where do we stand with this?

 

nippper