OK gang this is Ken's puzzle for this month is.........

I keep blowing turn signal fuses. Let me tell you what I've done and found (or not found) so far. I'll replace the fuse (with the engine off) and the turn signals will function as intended. I start the car and the turn signals work just fine for several miles, but (it seems) that when I turn the ignition off something causes the fuse to blow. When I again start the engine turn signals are gone and the fuse is now blown, again.

I can find no damaged or grounded wire, as a matter of fact I have replaced several older poor splices that some bubba had done just in case.

I can find no super heated or melted wires.

Part of my confusion comes from the fact that they will initially work after fuse replacement and being driven then malfunction and blow the fuse.

Any ideas guys?

 

Ken,
I have a similar problem in my 71 Vert. I replace the fuse and all is well, If I takethe car out for a drive and don't rev the engine over 4500, the fuse holds. If I get on it bang it blows. I checked from the column to the tail lights and can't find a thing.
Mark

 

I understand Mark. It's driving me crazy (short drive I do understand) I sure hope that those of greater experience jump in to help.

I can't even imagine what a friggin electrical shop would charge to find my problem or how they would treat Goldie

 

Could be in your backup lamp circuit. Try unplugging the backup lamp connector. Do you have a 4 sp or auto ?
AC or just heater ?

 

About 25 years ago, I chased a similar problem. The customer would take the car out and bring it back days or weeks later with a blown fuse. I found several things that I thought might be the problem, but every time, the customer brought it back with that blown fuse. I couldn't make if blow in the shop, and just about gave up on it, when by chance, I backed it out of the shop with the signal on. The damn thing blew. I stopped the car right there and replaced the fuse which promptly blew again. Now I got ya. The body was in a twist up the ramp to the door. I realized then that the owner lived in town and did a lot of sidewalk driveway ramping, so I understood why I couldn't get it to blow before. I found that the factory dropped the wiring harness when they put the speedo gauge cluster in and pinched the harness between that heavy metal support and the cluster. After those many years it had worn through the harness and contacted the wire for the LH signal. Just a thought. Might want to check that. Also in that same car, I found a penny down in the lighter socket. You might also want to check that one.

 

Hey Roger , it's a 4 speed with air

 

Out under the hood around where the throttle cable comes through is a 2 wire connector ,pink and green wires,unplug that and try a new fuse. If the fuse doesn't blow the prob is in the reverse lights.

 

OK Roger you are now my offical hero of the day. Followed your directions on unplugging the T connector, changed the fuse and went for a ride. Made a total of three stops (meaning park removed keys do something come back and restart) and just da-um all of my turn signals work just fine. My most sincere thanks.

[SIZE="1"]Just one tiny last question, is their a simple way to determine if it's the back up light switch or a wiring problem?

Again thanks.

 

Your Welcome !
Put an ohm meter on the connector going down to the trans and check to see the switch is operating and then put one probe from the ohm meter to ground and see if you get continuity.
I'm "guessing" but I would say you will find the problem on the green wire going to the back of car. You can disconnect the green at the rear harness connector in the left kickpad and check from there back.
My money would be on the backup light sockets.

 

Awesome dude, thanks. I'll supply results shortly
[

QUOTE=...Roger...;1574632032]Your Welcome !
Put an ohm meter on the connector going down to the trans and check to see the switch is operating and then put one probe from the ohm meter to ground and see if you get continuity.
I'm "guessing" but I would say you will find the problem on the green wire going to the back of car. You can disconnect the green at the rear harness connector in the left kickpad and check from there back.
My money would be on the backup light sockets.[/QUOTE]

 

Or the wire is rubbing on a hot muffler pipe.

 

Very possible but IMO if its on any part of the exhaust I would bet its on the pipe running past the tranny and the first ohms test should catch that.

 

Guys my knowledge is limited which is why I seek help. If I had the bucks to put Goldie in a shop and just say fix it I would. But I love working on and learning of my Vette.

Please expalin in the simplest steps you can as to how to check the rear switch/wiring for the trouble area. I am not an electrician and therefore have VERY limited understanding of ohms and such.

This newbe/oldtimer really appreciates the help.

Ken

 

Leave the 2 wire connector unplugged in the engine compartment.
Remove both backup light bulbs.
Touch both your ohm meter probes together and watch the meter-this is a dead short to ground.
Go to engine compartment,ground one of your probes,touch the other probe to the green wire in the 2 wire plug going to the rear of the car ( not the end going down to the trans)
If you get the dead short reading the green is grounded somewhere.

 

Ken , how we doing ? We can use a 12 v test light for testing also if you don't have an ohm meter.

 

I'm trying Rog I really am. What setting should I set my Sperry Volt/Ohm meter at to test the probe to probe thing and what kinda of numerical reading should the test dead short deliver to me? Once I have a bit of a grip on that I can ground one probe and insert the other and see what happens. Is it to be assumed that if I get any reading I have resistance (short) in that wire and why might it not be the pink wire?

Also can't I just run a hot wire to the green wire with bulbs in and see if current passes through?

 

You can set it on 200 ohms scale or the lowest setting.
Touch your probes together to get what a dead short looks like,my meter says .2 on the 200 scale.

The reading you want is an open reading,the same as when the 2 probes are NOT touching.

The pink is your hot lead and since the fuse doesn't blow most likely until you go into reverse the short will be in the green wire.

Yes you can put 12 v to the green and see if the bulbs light. Use the pink to do this because its fused. Leave the connector apart and jumper the pink and green with the key on. If it blows the fuse the green is shorted somewhere.

 

OK cool, thanks for the smiplicity. Did set the meter at 200 ohms and got a bunch of readings settling at near the .2

Worked on the green line with a good ground and got no reading of resistance at all. Replaced the back up light bulbs and ran a jumper from green to pink (good fuse) and started the Vette. turn signals worked and when I turned off the ignition the fuse did not blow.

Where do we stand now Doctor?

 

Now you have to work on the wiring going down to the trans switch. Look for the green to be melted to the exhaust. Could be shorted switch but I've never seen one.

Nice work by the way !!!

 

Oh ... did the back up bulbs light ?