corolla 2000 turn signal to trailer

So this is the problem.

Got a new trailer, installed a 4-way wire converter wired up so that we can tow the new trailer. But, most of the time the turn signals/hazards don't work on the trailer. They light up on the car, but not the trailer.
Troubleshooted over a number of days and found nothing.

This is what I did:
1st I checked the voltage for each signal light when it clicked on or off from the relay and the result was a random inconsistent fluctuating voltage ie. 1v 3v 7v 6v 0.1v 8v 2v 9v etc. etc.

That first thing does not look right. I believe it should be about 12v 0v 12v 0v etc. etc.

2nd I hooked the trailer to another vehicle, and the trailer's signals & hazards work! So ruled out the trailer.

3rd Disconnected the alarm system to see if that helps. No results.

4th I try cleaning out all pins for the fuses & relay. Still no go.

5th I open the relay and see if cleaning out will work, and still no go.

6th I replace the relay with a brand new (heavy duty) relay for the car! And still same problem!

7th Also tested someone's trailer on their car and it works there, then on my car and same problem.

8th Check voltage near relay area under the dash at driver's side, and same inconsistent voltage that fluctuates all over the place.

Another thing I did was change the entire 4-way wire converter to another new one and still same problem!

It defiantly is something wrong with the car! I've done everything I can think of. I'm totally stumped and I have no idea what to do?

Why are you using the converter - isn't the Corolla's wiring directly compatible, or don't yours have separate brake and indicator lamps?

Hi oldspark,
The Corolla doesn't come with any trailer adaptor or wiring ready. It's basically a 5-way lighting system, and the trailer is a 4-way.
The Corolla has separate brake and indicator lamps, whereas the trailer has the brake and indicator lights in the one light (same bulb used with another filament in the bulb).

Today after posting I pulled out the instrument panel and checked that over also with a multimeter, and still same problem with random voltage. Then I tried cleaning out the signal stick near the steering wheel, but still no go.

I know it could be something simple, but I can't figure it out! So thought I'd post on here to get some input that it might help fix the problem.

You might be better off using a test light rather than a DMM.
The "random voltage" may simply be the DMMs average of the flasher on & off time - ie, if it changes between 12V & 0V during the DMM's sampling period.


I'd also check each trailer lamp at its plug for proper operation - ie, feed it +12V and ensure all lights. (Can also feed +12V to all except GND to ensure no bad GNDs.)

I've also tried the continuity test light, but no go. That might explain the random voltage, though I've never seen it even reach 10v. But I am still stumped why the system fails for the trailer.

I installed a curt wire converter, and since then changed to another curt wire converter. Still same problem.

With the trailer, I tested the lights on another vehicle and the lights all work perfect. Tested two trailers, the enclosed trailer and someone's boat trailer on the Corolla and both trailers have the same problem only on the Corolla, not on another vehicle. So it defiantly is the Corolla.

Now the trailer lights do work... sometimes!
When I turn the indicator lever left, then the left lights signal for the car, and sometimes for the trailer, but mostly fails. Same for the right side as well. It's an intermittent problem.

I know the converter has safety features in it, which would shut all power off to the trailer if there is a short or some other inconsistent problem. So it seems the converter/s shut power off depending what the voltage is when I turn the signals on or the hazards on. If I turn on and the voltage seems to be at a nice number, then it all works. Though the indicators will work until I turn off an/or switch to another side of the vehicle for the indicators, then it's the same problem.

Very annoying.

There's gotta be an underlining problem causing all this!

But now I'm just doubting the whole random voltage thing as it defiantly makes sense the DMM isn't fast enough to read everything!

I'm starting to wonder if I should install a new line of 12v of power from the taillights for the trailer turn signals, with a relay that uses the current signal from the car's indicator lights which would get wired through the converter instead of directly from the current turn signals from the car.
Do you think that might work?

Another solution would be to buy another part completely different to what I'm using now.

Some flasher cans have difficulty driving extra lamps, though combined hazard/flasher cans shouldn't - except perhaps in hazard mode (ie, 6 hi-power bulbs instead of 4).

But "slave" flasher bulbs can simply be powered from a normal relay whose coil is across the normal flasher bulbs - ie, switched flasher can output to #86 and #85 to GND. The added bulb power (#30) can be from fused +12V with output #87 to the bulb.

However, since you have a combined stop/flasher lamp, you must turn off the stop light whist the hazards or flasher is active (ie, whether the bulb is on or off during flashing).   


I'd probably add separate flasher lights and ditch the convertor.
The stop bulb could remain as is, or changed to a single-filament bulb. (I'm surprised the trailer uses a dual hi-power filament bulb. Usually it's a single filament since other switching has to disconnect brake light +12V whilst that side's flasher is flashing.)

Do you think changing the trailer lights to an LED system might help?

Also thinking of getting a module that get's power directly from the battery like the ModuLite Trailer Light Power Module-119146. I've got a feeling the lights on any trailer draws too many amps from the lights on the car thus the converter cuts off power.

I had thought about adding separate flasher lights and ditching the convertor. But, have to register the trailer and have it pass inspection and not so sure on trailer rules around here. Also be good if I could just plug in any small trailer to the vehicle and have it work correctly without needing to install new lighting for each trailer.

Thanks for pointing that out about having a combined stop/flasher lamp and needing to turn off the stop light while the hazards or flasher is active. That sounds quite annoying to always have to remember that, especially on a road trip.

If I go the relay route, do you have any recommendations where I should gain the +12V power from?

Could I get it from fuse box area under the dash? I've provided a photo of the wire which I actually tapped into for the alarm system giving that it's own fuse as well. But that was a different project. So ignore the writing in the photo.

Okay, so here's what I found!

First thing, stop-light doesn't work all the time as well, just like the turn signal lights. Defiantly a flaw in the Curt wire converter design that it shuts off. At least that's what it appears. Did an amp test on the trailer light, but it showed about 1+ amp, not much. But probably should have tested from the car itself. Would the location of the amp test affect the reading?

Second thing which could be good news!
I discovered when inspecting all the lights on the Corolla, that the front indicator/hazard lights are one bulb with two filaments. In other words it is not the same setup at the back, it works as a park light (constant when headlights are on) as well as the indicator/hazard lights when I turn either one of them on via the hazard button or the indicator lever near the steering wheel.

So this is something going through my head as to whether if it were possible to run the trailer's wires from the 4-way plug all the way to the front of the vehicle to both Left and Right. So basically, ditch the wire converter and go directly into the indicator/park lights at the front for the trailer's indicators/tail lights. It can't be pulling that much amps?

The only problem I'd be left with is the brake lights, again into the same light system.

So after all that, maybe I should opt for making my own system with relays to allow that all to work. Slowly I feel I'm getting somewhere.

European towing adapters were 7 pin to allow for separate stop lights indicators with an uprated flasher unit.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Makes more sense, howie II. Over here majority of trailers have the stop (brake) & signal lights combined. Very frustrating when it comes to needing some converter that doesn't work. The converter I've been used (tried two of them with same problem) are the Curt 56175.

mechanicalhobby wrote:

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... needing to turn off the stop light while the hazards or flasher is active. That sounds quite annoying to always have to remember that, especially on a road trip.

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It's not annoying at all. It is completely automated. And that's how it has to be. It is looked after by the switching circuitry that combines the flasher filament with the brake filament.


I'm assuming you have not tested each individual trailer lights with 12V as I suggested, and then in combinations with 12V - ie, brake & left flasher, brake & right flasher?
It wouldn't surprise me if it is a trailer fault - no or faulty ground for the brake/flasher bulbs.


Yeah - front flashers are a different circuit. It is rare that I see stops lights operating on the front of a vehicle (ground faults excepted).   

Older local and Jap vehicles had dual-filament flasher/parkers, but these days they are dedicated flashers with separate parkers, hence better contrast when flashing with parkers on.

Most modern wiring uses dedicated lights for a function - ie, stop and indicators are separate as are parkers, indicators, and reversing lights.   USA is an exception.
The 1:1 mapping makes additions, extensions & trailers etc a breeze.


And forget LEDs etc. Even a properly working bulb system may not work with LEDs (LEDs are easily grounded thru other bulbs or parasitic voltages and grounds).
Find out what is causing the problem first - ie, test the trailer filaments.

I did test the trailer on another vehicle, and that worked perfectly along with another trailer, but testing both trailers on the Corolla failed the test.

I'll try your recommendation with testing each bulb & filament with 12v.

Thing that get's to me is the wire converter installed in the back trunk. Sometimes the voltage comes out, and sometimes it has nothing coming out whatsoever. At least most of the time it fails.

So I'll do the individual light bulb & filament test with 12v then if that looks okay, then maybe move the ground wire that goes into the converter and actually tap into the car's body instead of put it on a grounded nut.

Got a feeling that maybe there is too many amps being pulled than what the system can handle, thus the converter shuts off. But first the 12v test and take it from there.

Have to work today, but will test later on and will post the results.

Alright, so I did the 12v test, straight from the battery!

Each light is working fine! But here is the interesting part, plugging the wire converter straight to the battery, ground to negative and each other wire individually connected to the positive, all worked as hoped!

I then did an Amp test for each two sets of lights. And the results are around:

Tail-light: 1.7 amps
Stop-light: 3.54 amps
Left-Indicator: 1.78 amps
Right-Indicator: 1.78 amps
Indicators-Combined: 3.54 amps (tested with both wires connected at same time)

With trail light & stop light or indicators combined, I read a total of around 5.1 amps.

The indicator/signal lights seem a bit high on the amps. The converter reads:
"Maximum lighting load capacity
Left/Right signal circuits (each) = 3.0 amps
Trail/running light circuit = 7.5 amps":

Not sure if that's the limit including the vehicle or not.

But it seems there is a fair bit of amps being pulled. The car's fuse limit itself is 7.5 amps for the indicators. With the current 6 amps about being pulled for the car's signals or hazards combined, plus another 3.5 amps for the trailer, that's about 9.5 amps total. I think the converter may not be able to handle the amps being pulled for this particular vehicle, though the Curt company said it should work. I know the wire converter has some safety features that cuts out if there is an overload or short. Thinking if too many amps are being pulled, than the wires would heat up causing the wire converter to short out.

Wondering if it's possible to get another type of unit that has it's own dedicated power source with it's own fuse. Would this be a good idea? Might go to the store and pickup something before it closes.

In summary, I think your problem is a bad ground to the converter.
I think your suggestion to ground it locally to a body/chassis nut is spot on.

That's about it, but I'll elaborate on other issues below...
And that's great testing by the way - if only others were so capable! {**)
My only additional check would be to power both indicators and stops at the same time and see if that load is ~3.5A or ~7A AND confirm that they are at full brightness.
That will confirm whether single or dual filament stop/flashers, and eliminate bulb GND problems.



Others issues etc (ie, oldfart's ramble:)

I wonder where the converter is being grounded from. If it's from a single rear light GND which is only for one or a few bulbs (1.7A or 3.4A etc) else a relatively long and thin wire, then it will have a BIG voltage drop. You could measure the voltage between the converter's input or output GND and the body/chassis. If it's more than a few volts...

The Amp readings seem fine, and the unit's "Left/Right signal circuits (each) = 3.0 amps" means 6A total. Yours are ~1.8A each.

1.7A x 12V = 20.4W so it looks like you are using normal 21W or 23W bulbs for stop and flashers. (P=VI)
Tails total the same so I presume 2x10W or 2x7W plus some 3W for license plate etc - not that that matters.

As to a converter with its own power source - no - the battery is its power source.
And these units should work fine. As their blurb says, problems are usually in the grounding though I assumed they meant the typical grounding problems in trailers etc (especially those that think a ground is adequately supplied through the hitching device!).
The only other problems should be in inadequate cable sizing.
Or if the loads (bulbs) exceed the converter's rating, but you are well within that.

And keep in mind that the only current relevant to the converter is the current going thru it to the trailer lights. It doesn't matter if the rest of the vehicle uses 100A for its tail (clearance/parking) or indicator etc lamps - that does NOT go thru the trailer plug.    


[ **And to use a DMM's high current mode - without blowing it apart! Some insist on testing across batteries and BANG! (An ammeter is like a short circuit (ie, low impedance). A voltmeter is like an open circuit (ie, high impedance). Even 10A testing a 1.5V AAA battery will blow the DMMs fuse.
And I dislike inserting the DMM probes in series with the circuit under test - I only have 2 hands! ]

Thanks.

Good News! Got it to finally work! And it works perfectly!

I did end up checking the ground to the converter by running a wire from the converter's ground straight to the negative terminal on the Corolla's battery. The result was the same problem!

Here's what I did:

I ended up ditching the current convertor which was the Curt Wire Converter 56175. To be honest, it was useless! Would have thought it would should have worked, but it just kept cutting out. I just don't think it is compatible for the Corolla, at least for my generation. I feel the Corolla just doesn't give it enough juice, so the converter cuts out. The Curt tech line said it should work for my vehicle. But tried two different Curt 56175 Wire Converters, and both failed on the Corolla.

So went to an auto store and picked up another Wire Converter with one major difference!
It had a 12v positive 20amp fused red wire on it that hooks straight to the battery. (What I had refereed to as it's own power source). The wire was a bit of a pain to guide it through the car from the front to the back, but managed to do it. My understanding is this converter get's signals from the same wires I had previously tapped into, rather than leech from the actual power from the car's lights. So when each light is turned on/used on the car, then the converter provides the power that is needed straight from the battery. The converter say's it's a Hopkins Short-Proof Power Taillight Converter. Part# 36365
The lights on the trailer are also much brighter than they were through the Curt converter/s.

The converter I bought today is supposed to support up to 8amps per function. Not bad.
It has the plug for 4-way, but it also apparently can be used for 5-way, 6-way or 7-way adapters, if I convert it to that that is. But 4-way I'm happy with.

It wasn't cheap, spent around $80 for it, but very worth it. I spent too much time on it already and gave up on the Curt Converter. Could have got it cheaper online probably, but I don't have time waiting for this in the mail, as winter is coming fast.

Do you have an idea what may have caused the Curt 56175 converters to fail like they did? I was thinking maybe the car can't keep up with the demand from the trailers, thus overloading the car causing the Curt converters to shut off power.

Anyway, very happy that it is finally working! Thanks so much for your help with it. I learned a lot along the way.

I don't now enough about those converters to comment, though it sounds like the newie with the direct battery source uses the lamp feeds to switch relays (or MOSFETs etc) that connect battery power direct to the trailer.

It may be that the Curt uses diodes or other circuitry, though I haven't bothered figuring out the conversion required. (I've done it so many times using various methods that I now have an aversion to even thinking about it, though I can recite the connections for the equivalent shared flasher/reverse filament switching using 2 DPDT relays etc.)
Maybe one day my curiosity will cause me to investigate further.


But I'm glad you got it working, though I'm disappointed it took another product and expen$e to do it. (And I hate unexplained but working outcomes - except for intermittent problems!)


And I'm very glad you learned a lot. Things like this can be tricky as heck, but can still be broken down into simple steps - or rather, certain things eliminated (in this case the product LOL!).


Best wishes. And as I alluded above, you have shown a great deal of competence. [Hey man, if "they" said it should (both!) work - but another product did - then I reckon it is not a simple problem. IMO - well done mechhobby; you might have to change your name to 'lechobby.]