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turn signal blowing flasher fuse

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8.5K views 12 replies 3 participants last post by  docvette  
#1 ·
I have a its-a-snap wiring harnessin my '39 chevy. The harness has all connections for GM column ,and I am using a cadillac column. I have two brand new sockets, and bulbs for the rear they are GE 1154. With that said here comes the nightmare.

A month ago I was sitting up brake lights, any the one on my passanger side kept blowing after a little bit (I only went through the second bulb). Last week I plugged in the relays for the turn signals and hooked them up (with new bulbs). One brake light blew, but both turn signals worked. I tried working on them a little bit ago to see if I could figure it out. Turned the car on the flasher fuse blew (no signals or brake now). Every time I put in a new fuse and turn the signal the flasher fuse blows.

I unhooked the wires from the lights and pulled them out to check to see if they were grounding out. with no cuts in the wires and nothing at the fuse panel to be grounding out I tried them again. Fuse blows when turn signal is on.

Is this a bad turn signal cam? Where do I need to look next?
 
#6 ·
Bulbs

Doc here, :pimp:

Do you have duel function, single bulb lights? (I.E. Separate Tail and/or brake, or separate turn and/or brake) in other words, do you have 2 sockets in the rear one with a single pad, one with a duel pad?

If so then you may need both type of lights.

IF it blows fuses with the bulbs unhooked, you have a wiring misnomer..somewhere in the harness, most likely you have a power wire (in the flasher circuit) Going to ground.

I don't know how many interconnect plugs they provide on your aftermarket harness, but if you can isolate front, rear and column by unplugging them, then with an ohm meter back track each section of harness for ground while unplugging it, until the reading goes away, the area forward of that harness is where you'll find your short.

Probably you'll find one of the column wires is grounded where it shouldn't be..since both brake light and turn-signal function feed from there.

Let us know what ya find!

Doc :pimp:
 
#7 ·
Just an update of where I'm at right now. I called it's a snap, and they said since I didn't have the front signals and back signals hooked up at the same time the flashers were overloading (not enough ohms) and blowing the fuses.

Doc, I am also using a single bulb in the back.
I am going to hook everything up, and see what happens.
 
#8 ·
signals

i have been doing this for more than 40 years, and this i ever hear of over loading the signal flasher and blowing the flasher or stop light fuse. i really think you have a dead short to ground. if you think the flasher is over loading you can get a flasher with the part number EL12 at most parts stores. it an electronic flasher that will blink the same rate with one bulb or eight bulbs. large trucks use them so that even if one bulbs burns out the rest will blink at the same rate. are you using a 15 amp fuse or better. if it blows a 30 amp fuse there is a dead short. try isolating the front from the rear, to find the section the short is in. is possible the builder of the harness made a mistake and it happens and he could have grounded one of the wires that should not be. with out hands on checking, all we can do is give you things to check and hope you find the trouble. good luck
 
#9 ·
signals

something else i thought of. if you have a spare turn signal switch or a friend that has one. plug it in the harness at the switch connection and operate it manually. if the steering column is been around awhile its possible that the signal harness going up to the switch maybe scrapped and grounded. just a thought. if everything is new you can try what i suggested earlier.
 
#10 ·
Wiring

Doc here, :pimp:

I tend to agree with Sedan Delivery, You ARE not going to draw MORE current running LESS items...just doesn't Make sense...

Do you have a Volt/ ohm/ current meter? and is it capable of reading more than or up to 30 amps?

If so..insert one probe in the Fuse holder for that system, set it for the highest current reading you can obtain on the meter, using an alligator Clip jumper on one probe, to a 30 amp or higher fuse (to protect your meter from over-current the fuse must be slightly less than max setting on the meter) Clip the other end of the fuse into the other lead of the fuse holder, activate the system, If the meter pegs and the fuse blows, you have a DEAD short...No two ways about it..

You will need to track down the source of ground on a power circuit and remove it..

Flashers that are under rated for the total load will tend to go on and stay on without flashing at all, and heat up..UNLESS they are for a 6 volt system..Then they will blow a fuse..unless the fuse is over rated..

Again, I think you have a short in the system, and the Column harness (or plug ) because of the interaction with the brake lights is a good candidate...I would be looking there...

Doc :pimp:
 
#13 ·
Kewl!

RodFather said:
FIXED...
One wire from the turn signal cam that goes down the steering column was pinched in the column drop and the insulation was peeled off. This problem was grounding out that wire, and only blew the fuse when the left turn signal was on.
Thank you all for your help.
Brian
Doc here :pimp:

Kewl!! Glad to hear you found AND fixed the problem...

Thanks for posting back too..It may help the next guy down the road... :thumbup:

I had a feeling you were going to find the malady in the column due to the Brake light involvement...AND that is the place of the most possible Chafing...

Most likely the guys at "Snap" gave you the bad info was because they were too busy to mess with "Customer Support" and sold you a bill of goods on phone about the diagnosis (even though, it had no basis in electrical fact...) hoping you'd go chase the problem a while and find it yourself..

I would say (if they weren't so far out of the ballpark on this one) That to diagnose a problem by "Remote control" Is one of the hardest things to do...You are not there to Actually SEE the problem/ symptom..
(try it yourself on anyone of these threads..)

You have to relay upon the input (complete, accurate, or not) on the part of the person submitting the query, as to the symptoms of the problem..then add what common sense tells you VS what the books say..and temper that with your own personal experience..To extrapolate at least a half~way intelligent probable cause..AND no two Takes on the symptoms will Equate to the same Cause/cure by any two readers..BECAUSE we all have the "Personal Experience" Factor involved..Which doesn't make the answer anymore right or wrong..just a different view..

Anyway, Glad To hear your Back on the road again!

Doc :pimp: