Sxrxrnr

I've been dealing with random brake light fuse failures for several months now. Fuse may last a couple of hours or a couple of minutes. I have posted to another thread and have checked out all likely or possible causes including replacing turn signal switch.

Here is the conditons I experience:

1. Brake light fuse will blow,,,I can see this via fiber optic system.
2. Then turn signals start acting strangely by flashing (when I turn them on) in an abnormal pattern,,not regular but somewhat randomly.
3. Turn signal fuse will then eventually blow.
4. Have replaced turn signal flasher 3 times in 1 month as they too will blow.
5. Replace brake light and turn signal fuses and wait for repeat of above,,,perhaps a couple of days or sometimes just a few minutes.
6. If I replace brake light fuse before turn signal fuse blows,,,it does not blow.

I have done the following:

1. Pulled all bulbs, replaced all of them and sockets are perfect and sprayed anti corrosive electrical product in them.
2. Inspected all wiring under dash and checked all going to rear of car with multi-meter. Again I have also replaced turn signal switch with a new on.
3. I then purchased the a Short Buddy. See video below on how it works. A really neat tool,,,,,,however set up for "blade" type fuses only, not glass tube types,,,,but with a bit of work can be made to work with our old Vette type fuse panels.

http://www.youtube.com/watch?v=us2s_CZ-Vwo

http://www.amazon.com/Electronic-Spe.../dp/B007K92I4A

4. I hook up Short Buddy. Hit brake pedal numerous times and soon get long "audio" signal from Short Buddy of a short. Wait for 30 seconds or so for signal to clear,,,,hit pedal numerous times and nothing but as normal audio system notification that all is well. Wait a few more minutes and hit pedal a few more times and may get short signal again,,,,at times 2 or 3 failures in a row and then none for quite some time.

Short Buddy acts as a circuit breaker and not a fuse,,,,,after it clears a short, you are good to go again for another run.

At times I will get 2 or 3 failures in a row, then hit the pedal for 10 minutes with nothing but normal audio alert and then will hit a failure again.

I have wiggled and jerked every wire under the dash and thruout car to the rear lights with the brake pedal depressed and cannot force another failure. I should note that each time you hit the brake pedal, you will get 2 short beeps from Short Buddy, brake lights will illuminate(I can see this from fiber optic system in the 71). When a short is detected you will get one very long beep and brake lights remain turned off, until Short Buddy resets itself and they then will illuminate.

The only way that I can force a short signal is to continually hit the brake pedal,,,,and I am touching nothing else until I get failure signal. Almost as though there is some timing countdown mechanism that the cars electrical system must go thru before it is time to post another short signal (or if running as per normal without Short Buddy, blowing another fuse).

At times I have turn on the hazard button and hazard lights flash as they should,,,,each flash generates an audio tone from Short Buddy and it goes crazy with audio tones. However Short Buddy has never posted a short signal when doing this,,,,,which might suggest a brake light switch failure,,,,,,however I believe that this is a grounding switch, so how could such a type switch incur a blown fuse via a short to ground. Hazard light system share same fuse with brake lights.

This random timing fuse blowing of the brake light system is really a puzzler, as though there is some type of circadian rhythm to which it marches.

Also why does a brake light fuse failure subsequently lead to a turn signal fuse failure and ultimately to a blown flasher(I think that I must do an autopsy on one of them to see what they look like inside).

Have never seen such mystery problem.

I will re-post to C1 Forum. Perhaps someone with a C1 or C2 may have experienced same.

0Willcox Corvette

Have you pulled the fuse panel apart and looked behind it/between it? I'm going to see if I have a schematic here to look at.. maybe I can help but I'll need see if I have one.

0Willcox Corvette

Ok.. I'm back..

There are two wires that feed power to the tail lamps.. (and it all goes though the turn signal switch).

You have the white wire which comes from brake lamp switch.. before the switch it is orange and runs straight to the fuse panel without interruption. it then hits the hazard flasher before moving to the fuse and power strip in the fuse panel. I don't think this is your issue unless you have something between the two halves of the fuse panel causing an issue.

The other wire is the wire is the purple wire that runs from your flasher to the turn signal switch. At the flasher this wire splits off and runs through the firewall to the TSC solenoid on the passenger side firewall.. Have you checked here for an issue?

This same purple wire hits the fuse panel and is divided there as well. The other side of this runs to the neutral safety switch (or back up lamp)... Have you checked there?

Post back when you can.

Ernie

DucatiDon

Bad ground on a tail light socket??

0Willcox Corvette

When you have a bad ground at the tail lamp socket and a neat trick.. two things will happen..

1) In the dash when you turn the flasher on the side with the bad ground the light in the dash for that turn signal will not blink.

2) The tail lamps will usually both burn but one side (the side with the missing ground) will be dimmer than the one with a good ground and when you hit the break pedal that light will go out.

He didn't say if it was auto or 4 speed.. but I feel there is an issue on that purple wire.. either in the neutral safety switch, the TCS solenoid on the firewall.. or the back up lamp switch. I have the original GM schematic on my web site too.. if you want to trace it out.

0Willcox Corvette

I've been reading your other thread a bit too.. Looks like some of my suggestions were covered.

But.. this is a very basic system... If you test the purple, white and orange wires for a short to ground.. and all is good.. then your going to have to start looking at components connected to the shared ground. Translation.. something else may be shorted and back feeding voltage on the ground side.. Example.. the door ajar switches share a black ground with all the rear lamps.. this ground runs through the switches and all the way to the dash lamp where it gives a ground to the pink wire on the dash bulb socket. This pink wire is also the same power wire that supplies power to the fuel gauge, temp gauge and so on.. So.. are the gauges doing anything funny when this is going on?

Food for though.. and I hope it helps you.

Willcox

Sxrxrnr

You guys are all hitting areas that I had not considered. Car was a 4 speed(now 5), had a TCS system that long ago(40 years?) was removed,,,must find where wiring for it deadends at now. I do have wiring schematics (Doc Rebuilds and Service Manual). Tail lights, backup lights, brake lights and turn signals are equally bright when operating. I do have a multi-meter, have checked voltages,,,all are normal at wiring harness and at tail light sockets. I have checked grounds at sockets and all are ok. Have not checked amperage draw,,,,but did once try a 25 amp fuse as a test,,,instead of stock 20 just to find if I might be running amperage right on the edge. 25 amp fuse blows also. Will have to follow schematics tomorrow to find how TCS could cause such a problem. I will check check recommendations tomorrow.

Given brilliant positioning of fuse panel, looks like a real bear to remove to check behind and make certain all is ok.

Except for lack of tubular glass fuse support, Short Buddy is a pretty good tool. Audio warning is valuable that you need not be look at instrument or even be close to it(can be at back of the car, while tool is hooked up under dash)to make good use of it. Would love to have glass fuse support as I would just leave it in place for awhile and drive the car as normal,,,,,as noted earlier it acts as a circuit breaker and automatically resets after each short failure,,,no blown fuses to replace.

Keep those ideas coming,,this is a real challenge.

0Willcox Corvette

Sxrxrnr.. Short buddy sounds neat.. I'll have to take a look at it..

But I've never had a shorted wire or a wire issue I couldn't find using conventional methods.

Sxrxrnr

Gauges work perfectly. I too was thinking of some type of feedback into the system. The reason being is as noted, the brake light fuse blows, turn signals when turned on begin to flash in a very erratic pattern and eventually this fuse blows and then too, I've had 2 TS flashers blow in 2 weeks. I do not even know what would cause a TS flasher to blow, except perhaps excessive amperage from some source, such as a short in the TS circuit that would damage the flasher before its fuse blows,,,,I do TS with proper 20 amp fuse.

As of now with the Short Buddy serving as brake light fuse (which acts as a circuit breaker), I never reach the point where the TS fuse blows, nor do I see this erratic pattern. It is only after the fuse is blown permanently that I see this erratic TS pattern.

I have pulled an moved all wires under the hood,,,,thinking TCS system as you mentioned and was unable to have SB generate a short signal. However what I note now is no failures at all no matter how many times that hit the brake pedal,,,cannot force anymore. I did take a probe and push in against spring tension many times the contacts in the tail lights,,,perhaps shaking something loose. However as noted, my tail light contacts look virgin with absolutely no corrosion of any kind. But then, I have operated for several weeks without blowing a fuse (example after replacing the TS switch 3 weeks ago,,,followed by blowing a couple of times in a single day.

I've also checked all wiring under and around the clutch, gas and brake pedals for any interference.

I stand corrected, the brake light switch is not a grounding switch, I spotted 2nd wire coming off it,,,I missed it before. Can these switches go bad and short?

Does anyone make a 20 amp circuit breaker that will fit into a fuse panel? Short Buddy is a bit bulky to use as a permanent fix.

Sxrxrnr

Same here until now. However it is proving invaluable now,,,,I likely would have blown 20 fuses just in testing today. It has often detected a short condition and rang the alarm, but as of now cannot find what triggers it,,,,all and I mean all that I must do is to keep tapping the brake pedal until eventually the alarm goes off.

The strangest electrical problem that I've ever had up until now is on my C1with a Ron Francis wiring system where I would step on the brakes and the turn signal indicators on the dash would both illuminate. Took me a couple of days to find and fix this one,,,,my wife kept telling me to quit looking at the dash when I step on the brake,,,I was beginning to think that she was right. She's now telling me to use hand signals when stopping or turning. Of course in Calyfornua half the drivers never use signals anyhow.

7T1vette

You asked whether the brake switch can go bad and short out. It can definitiely go bad, but I think it would just pass voltage or not pass voltage. If there were some way an internal contact or metal part could fail and somehow create a short to ground, that could be your problem.