Having a real hard time with an electrical problem.  Been one thing after another.  I am currently pulling my hair out on this.


Headlights work fine

Marker lights work fine

Break lights work fine

Rear lights when headlight/marker lights on work fine

Turn signals do nothing

Flashers do nothing

Replaced fuses in fuse panel

Using new turn signal switch(connected but not installed in column)

First Welcome to C2VR.  I had the same thing happen but I knew my turn signal's worked the week before.  What it turned out was the flasher was not seated correctly.  That sounds simple but I had the flasher in and out a couple of times even went and purchase a new one and that did not work either.  was frustrated and started all over again with the flasher and it started working.  I backed off real carefully. 

Do you own a set of electrical drawing for your car or better yet the GM shop Manual?  If you do not that is the best and only good authority when it comes to working on your corvette.   The other one I like is the Corvette Assembly Manual which just show you the assembly drawings that were used when they put your corvette together.  I have found it handy. 

The help I'm providing is using my 82 shop manual so if someone else has a correct manual or an 78 car take their advice over mine. 

It is a simple system but that does not mean it is simple to fix if it is in the wiring.  Does your Hazard warning flashers work?  If they do then everything on the other side of your switch is working correctly.  Your switch is new so that basically leave the power going through your fuse box. but if you have a book you already know this if you do not I can copy and pdf a couple of pages of my manual that diagrams the circuit and talks about how it works.  

I work from home so just email me if you want the pages.  Sorry I cannot be of much more help but

I did replace that flasher a half dozen times before it started to work so I'm guessing bad connection in the fuse box.

tb2k82ce2011-07-19 08:53:23

If both the turn sigs AND the hazard flashers are not working, I'd kinda suspect the t signal switch, myself. The turn sigs and the hazards use different flashers, but it is entirely possible that BOTH flashers are bad, or even missing.
IF the indicator lights in the dash are not even coming on when you use the turn sig or the hazard, I'd be going for the flasher(s) first. I think on the '78, the hazard flasher is in the fuse box, and the turn signal flasher is under the pass side dash, at the lower edge. Someone correct me if I be wrong.


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Joel Adams
C3VR Lifetime Member #56    
My Link


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[QUOTE=Adams' Apple]If both the turn sigs AND the hazard flashers are not working, I'd kinda suspect the t signal switch, myself. The turn sigs and the hazards use different flashers, but it is entirely possible that BOTH flashers are bad, or even missing.
[/QUOTE]

I have no flashers inside or out.  I also have no signals or flashers.  I replaced the can in the fuse box.  I could replace the other one in the passenger side as well I guess. 

@tb2k82ce

I do own a  pdf of the wiring diagram for my 78 in addition to about every shop manual I could find, Hayes, chilton, Gm, etc.  I reference all of them constantly.

Here is some help welcome to C3VR

Well, I be darned!  Reseating the the can in the fuse box caused the turn signals to start working again.  However, they are really dim and blink awfully fast.  The indicator lights on the dashboard for the turn signals are out, could that cause this? 

I still dont have hazards working. 


I am so out of practice on car electrical.  I have not had to really work on a car like this since the mid 80s with my firebird.

I would recommend replacing the flashers. Just make sure the terminals in the fusebox are nice and clean, with no corrosion.
The indicator lights should have no effect on the signals themselves working.

Adams' Apple2011-07-19 20:07:04

______________

Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Like I said earlier I pulled and replace my flasher cans over three times and then it all started working.  The slow flashing I would bet is a bad ground or contact.  Again I would suspect the flasher connections.  Blubs are cheap replace them. 

bulbs bad will change the flash rate. power is at the flasher then through the combo switch to the bulbs to ground, bad grounds will also effect the raterraider12011-07-20 10:03:23

Turns out the flasher can was not correct.  I replaced it with a spare I had and fixed the intensity and the speed of the flashers.

I swear this is car is cursed.

When I put on either turn signal, I get instead hazards.  When I use the hazards, I get nothing.  All other lights seem to still work.

I feel like I am chasing a problem that morphs every time I think I have it fixed.  Frustration is mounting.  Give me something mechanical any day!!!

Let me see if I have this correct you have the new switch and you have checked it for correct installation the connectors were cleaned when you put it in. You have flashers that work now that they have been installed a couple of times.  but gremlins are working in your car.  I have found that most gremlins come down to bad grounds.  Easier said than fixed because you have to find out where the ground spot is. On a Corvette this is almost as hard to do as it is a Jaguar. 

Your car is different enough from mine that I cannot help in some areas.  But just looking at the diagram that was provided I have a couple of questions.

Do the stop lights work and if so what happens when the turn signals are turned on and brake is depressed?  if the stop lights come on then your grounds are ok for the rear lights anyway. 
I can not see that there is a cross between the Hazard system and the turn signal system except in the switch.  It looks to me like the hazard disengages the turn signal system.   I would clean the flashers and check my connections on the switch.  I would also look at the wire bundle that goes to the switch and make sure it is not cracked or there does not seem to be a short. Do you have anyway to measure voltage?  even a light as we are looking at having 12 volts or nothing.

[QUOTE=tb2k82ce]Let me see if I have this correct you have the new switch and you have checked it for correct installation the connectors were cleaned when you put it in. You have flashers that work now that they have been installed a couple of times.  but gremlins are working in your car.  I have found that most gremlins come down to bad grounds.  [/Quote]

Yes, I have all the correct equipment.  It was tediously clean with a small brush to make sure I good connections.

[QUOTE=tb2k82ce]Do the stop lights work and if so what happens when the turn signals are turned on and brake is depressed?  if the stop lights come on then your grounds are ok for the rear lights anyway. [/QUOTE]

no, my stop lights no longer work.  Not sure when that started but its new.


[QUOTE=tb2k82ce]I can not see that there is a cross between the Hazard system and the turn signal system except in the switch.  It looks to me like the hazard disengages the turn signal system.   I would clean the flashers and check my connections on the switch.  I would also look at the wire bundle that goes to the switch and make sure it is not cracked or there does not seem to be a short. Do you have anyway to measure voltage?  even a light as we are looking at having 12 volts or nothing.
[/QUOTE]

I will take everything apart and clean some more.  The wire bundle is in really good shape.  I will double check it for loose connections after this call im on wraps up.  I work from home. :)

I really appreciate all your input and suggestions guys and gals.  Electrical is not my strong suit.

Hi Valentine,

Also corrosion can build up at the bulb sockets and the bulb contacts.  It can increase the resistance and upset the timing circuit. It can be on the connectors where the flasher plug into. This can give you strange intermittent problems.  I use Deoxit D5 - or what ever they are calling the stuff now - by Caig Labs.  It is a contact cleaner and removes this corrosion  so you get a good clean connection.  WD-40 is not a contact cleaner. Do not spray that on anything electrical.

All the best,
Keith


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Nobody ever waves when I'm driving the Explorer.
K Woody

Having your stop lights not work is not a bad thing from the troubleshooting point of view.  We must get them working first because it is the simplest.  Battery then brake switch, turn signal switch (in its normal position) brake light bulb and ground that is it.  Unless that is working nothing else will work.  That is how it works looking over the diagram that rraider1 "Robert" provided. 

Your system is different from my 82 so that is all I have to go on.  I would say you need to find where the ground is after the stop lights.  Unless you have blown a fuse your brake lights will work 100% of the time.  (I'm assuming that the blinker control switch that you purchase is not bad.  Looking at the drawing that makes me say there is a good chance that it is that ground could be part of if not all of your problem.  It says the location is under the left end of the rear cross member. 

Do not just tighten it down.  I did that once and all it did was compress rust which is not a good conductor of electricity.  When you find it clean it and then screw it back in. 

If you can not find it or you want to check it out before you take it apart you can make a jumper out of an extension cord and connect to the ground side of the tail light and then clip it onto a good ground (I like going back to the ground side of the battery). 

I made a long set of test leads out of an outside extension cord.   I connected alligator clips to all of the ends It is about 10 feet long (I use shielded alligator clips you do not want to short them together when you have power on them). 

Now I can ground anything anywhere or provide power to anything to test it.  (the wires are not for heavy duty circuits above what ever your power cord was rated at.  I used an outdoor 20amp power cord).  Remember we are talking about test leads.

I used it to prove to myself that the window motors worked saved me a lot of time trouble shooting as it turned out to be the switches. 
tb2k82ce2011-07-20 17:01:14

Resolved!!!
Finally got to the root of this after taking a small break.  Since i had replaced the turn signal switch, I had a great octopus connector to run jumpers with. I was able to determine that the problem lie somewhere in the rear end as suggested earlier.  I was not able to figure it out however.  After staring at several wiring diagrams, I notice the switch for the break pedal.  I got under the dash and checked it and sure enough, the lights all went wonky when I played with it.  It was acting like a passthru open sometimes and was grounding other times.  Replaced it and my problem went away. 

I really want to thank everyone for the help.  This was a total learning experience and your help along the way was what got me thru it!!!  Thanks again all!!!

Kewl!
The brake lights go thru the turn signal switch, so that does make sense.
Glad ya got it taken care of!


______________

Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"