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SBU turn signal relay repair

8K views 28 replies 11 participants last post by  gottabediesel 
#1 · (Edited)
So I finally got around to repairing my turn signal on the 1300L. The problem occurred when trying to repair a turn signal socket. Something had shorted out causing only the left side to work. Anyways, I finally located the relay to the driver side of the steering column about midway into the dash. Mine was the tin can style which opens very very easily. Once opened I noted how complex the unit was. I finally found a component that was burnt. It was a nichrome wire that jumped terminals. There were three of these wires with only one burned. They are seemingly intended to dissipate heat for some reason. After testing the existing wires they were found to have near zero resistance. So with a lack of .030 nichrome wire I decided to use some solid core .030 welding wire I stole from my welder. I bent the wire to match the profile of the other existing wires and soldered it in place of the old burnt wire. The relay re-assembled nicely and some epoxy was used to hold down the insulator plate in lieu of the small crimps I had to file down to disassemble the unit. Anyways, the result of course is that both sides work now. So hopefully if this happens to anyone in the future they can save the $300 for a new unit and fix it like I did. Oh and since the exact location of this flasher is a bit hard to find on the Internet, hopefully this helps a few others locate it. Again, remove the dash cover and look to the left of the steering column at about the same level as all the other relays. It is bolted into the side of the relay brackets. Mine was silver but some are black plastic.
 

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#7 · (Edited)
good work.

for future refrence, these relays have two outputs. some even three. the first output runs the truck signals. the second the trailer. if the truck circuit fails, you can just switch the wires in the plug to run the truck off the trailer output and get maybe another 30 years out of it.
 
#9 · (Edited)
So, what part would we replace to make them function with LED lights? I noticed that with my old travel trailer attached, the first and second turn signal lights on the dash would blink. When I pulled my new toyhauler...with LED lights, the first would still blink but not the second. The trailer lights do blink even though the second dash light doesn't. Now, I replaced the taillights on my mog with LED lights....Thanks to Joerg, Merek and Scott at EI....the first dash light doesn't blink either...even while towing. All of the vehicle/trailer lights blink just not the dash. I understand that an extra "conventional" bulb or a resistor in line will make enough load to make them blink but I'd rather use/make it work without just adding more load. The lights are amazing and so much safer to be seen and even backup with them.
Thanks, Chas
 
#12 ·
the dash indicators are there to show if all your bulbs are working so when you use LED's that draw less current, they will not light up indicating a burned out bulb. you can cheat and wire them right at the relay (can be done right at the relay plug) so they run off the actual signal light output and use one for each left and right side instead of one for the truck and the second for the trailer
 
#10 ·
Excellent work DokaTD!! I also enjoy seeing someone dig into a problem and solve it by repair instead of replacement.

Those nichrome wires are probably current shunts across which the circuitry monitors voltage change, which then triggers blinking. LED lights probably do not draw enough current to create trigger voltage across the shunts. Most likely, if the length of those shunts were increased, voltage would go up and the blinker would trigger with LEDs.

How much to increase length? If current load was known for normal lighting, and current measured for the LEDs, then increase the resistance (length) of the shunts in inverse proportion to the current ratio, the blinker would work.
 
#11 ·
Those nichrome wires are probably current shunts across which the circuitry monitors voltage change, which then triggers blinking.
Yes - that should be how this works. The original wires DO have more resistance then regular copper wire but probably not measurable unless one has the proper equipment. A regular shop ohm meter won't work.

MIG wire is probably a pretty good approximation, being copper coated steel. If someone else tries this and finds it doesn't work, try sanding off the copper flashing. This should raise the resistance-per-inch a bit :)
 
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#16 ·
wish I would have read this thread as 1/2 a day was spent trying to get a left front turn signal working.there seems to be 4 outputs, one for each front and rear light, left and right. Only problem is I tryed wiring the left side front and rear signal output to work together and now the front right doesn't work. If I put a LED bulb in the front turn signal,the dash turn signal also lights up along with the four way indicator when hazards are on. There must be some sort of balancing circuit in the relay for some reason.
 

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#17 ·
Not long after installing LEDs for my tail lights the whole module died.
I bought the new one, something like C$ 450, and of course installed resistors, this time around.
It lasted a few years, I believe , but then one day again , the module died.
The vision of spending another $500 made me think.
I took the module apart, and found out the relay inside was toasted.
I removed it from the board and soldered 4 wires in place, each of different color to make it easy, run the wires outside the box, and ran them to relay socket, which I glued to the outside of module housing.
This way I was able to use regular or even more powerful relay for that matter.
Sure enough, year later relay died, this time replacing relay was way easier.
My plan is to get rid of resistors and use, solid state module.
One day probably...
 
#18 ·
reading through some of the other posts, could there be something with the addition of LED lights that cause problems with these older type of relays originally designed for higher current? Doesn't seem to make sense and it could be just the age of the relays but it would be interesting to see if owners with original light systems (not LED upgrades) experience problems...
 
#19 ·
It is the LEDs.
They draw way less power than regular incandescent bulbs, so by default the module reads them as burnt ones.That's why you should put resistor in the circuit to change the load on the module.
That's OK, not the smartest way, but it's easy one.
Installing solid state module and eliminating resistors is IMHO the way to go.
 
#21 · (Edited)
A quick google search came up with a few wiring diagrams and indeed it does look like it is for the intermittent wipers. Seems like a worthy add on. More details in another thread perhaps?

There are more diagrams than this - but this one should help.

Also - there is another thread that goes into a little detail about adding this unit here.
 

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#24 ·
They are seemingly intended to dissipate heat for some reason. After testing the existing wires they were found to have near zero resistance. .
Hey there DokaTD. Those short bits of wire are there to detect that current is flowing in the lamps. If yes, the lamp in the dash will flash along with the indicators. I think there's two wires that detect 2 Amps and two that detect 4 Amps. Something to do with the trailer circuit for the 4A.

You may have got lucky with your repair and hit on the right resistance. If your dash lamp is coming on, that's probably good enough. You could try measuring the resistance more accurately and substituting something identical. Wouldn't matter what you make it from as long as it can take the current. I know it seems like it's zero, but it's something specific, can't remember what. Fractions of an ohm. When there's enough current flowing, then there's enough voltage between the ends of the wires to trigger the detector.
 
#29 ·
Would it make sense that the addition/ change to led lights could damage the blinking/ flashing modules? It seems from discussion that resistors make the circuits work but there still is damage to the modules after a while. To fix this, if another bulb was put in the same circuit, could that solve the issue? as long as you didnt get carried away..
 

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