Bought my second c4 about 3 weeks ago. 1993 coupe. Yesterdaywhen i tried to turn the car over i hear a slight clunk and all electrical systems go out. Is there a master circuit breaker on the battery? After a while the car resets itself and the power comes back on. I can put the car in run but whenever i try to start it dies again. Any ideas. Very frustrating. Thank you.

Sean Murray

 

Check battery terminal connections. Pull them off, take the bolts out and clean them up. Check for corrosion, signs of acid leakage from the positive terminal.

Good Luck, hope it's that sinmple.

Pete

 

Nope. pulled the battery cleaned every thing up. Put a new battery in.

 

bad fusible link? bad starter? last but not least, (hope not) could engine be locked up? :sad:

 

engine isnt locked up... Anyone have an electrical explanation or theory. I am an electronics engineering major so you can be heavy on the tech.

 

There is no master breaker. But, there are 8 fusible links on the jump start junction block and 3 that are fed from the positive cable on the battery. There are 2 grounds, one on the frame and one on the left rear of the head. If you lose electrical power, then either ground or the positive lead gets disconnected. When you lose power, use a voltmeter to determine if the ground terminal disconnects or the positive terminal disconnects. When you determine which becomes open circuit, then hunt for which connection is at fault and correct it.

 

Why would the car reset itself and the power come back to the car after a period of time if it was a fusible link.

 

Did you check for codes? :seeya

 

yeah...no codes...

 

is this a stick? or auto?

This could be as simple as a bad clutch interlock switch or something like that. Also, could be the auto equivelent, the neutral switch...

The switch could be bad, and upon releasing the clutch, the engine dies...

who knows... just a couple of ideas...

 

The connection has become intermittent. It may work at low current levels, but when high current is demanded it causes heat which increases the resistance and causes it to open again. Each repeated demand will cause more damage to the connection and reduce current ability until at some point it does not work at all.

As you have not applied a lot of troubleshooting data, it is hard to determine exactly which connection has gone high Z. But, it is clear that a high current connector or device is involved by your description. Therefore, trace all main lines from the battery to the starter, and find the main connection points. One or more may be bad. JFB has done a good job of providing these major points of both B+ and ground.

Just one last point, and I am sure everybody on this board is sick and tired of me saying it. However, I can't tell you how many times I have helped a friend with this problem and asked them to check the battery connections and they said it was fine. So when I pull thier connections and get the bolt out they are shot, totally messed up. A good cleaning later it works like a champ. Classic problem on a side terminal battery. Don't mean to be insulting, just that it looks great until you take it apart, then the problem becomes clear.

Follow the circuit in logical order and don't forget the grounds. You are looking for an intermittent open, most likely caused by a bad connection. There is not much in the circuit except wire and connections (for the symptoms you describe).

Good Luck,

Pete

 

It isn't the fusible link that is intermittent, its an intermittent connection from one (or both, but unlikely) of the battery connections. I would vote for a bad connection from the red wire (input power) on the ignition switch which opens when it gets warm and makes contact when it cools off and shrinks . Since all your lights go off and the starter won't crank, those things get power through the ignition switch. The ignition switch may be defective too and you can verify this by measuring the voltage on the red wire supplying power to it and then in the "run" position (when car won't work), check for 12 volts on the pink and yellow wire (on my 87 these are ecm, inj, vats and start enable relay respectively). It would help immensely if you had an electrical service manual which has a schematic of your cars wiring and you could trace the distribution of power when it fails and then find out where power is interrupted and fix it.

 

No offense taken on the battery terminal thing. I understand where you are coming from. They are clean. I guess i'll pull the car apart today. The starter isnt connected directly to the ignition switch though, right? That is a low current relay so the starter has a straight run to the battery. Doesnt really matter because the short would have to be on the master line before any of the fuseboxes, that is if it is an expansion short. If it was a short in the ignition (which i believe is low current) it wouldnt effect the rest of the electrical systems (the systems that get current all the time). I'll have to take a look at some wiring diagrams. How difficult is it to trace the positive line into the car?

 

I had a 66 big block el camino that did the same thing, the negative battery cable was loose at the engine block, it would work at low current as was stated above, but as soon as the starter tried to engage the whole car went dead.

Just my 2 cents

 

I am not able to get through to you. You have an intermittent open circuit, not a short circuit. A short circuit blows fuses, or if unfused, gets red hot and makes smoke. The battery power gets to your ignition switch through a fusible link and then threw a 100 pin connector on the firewall into the car to a terminal on the right hand side of the instrument panel, and then on to the ignition switch. Some members have posted that they had an intermittent on one of the pins of the 100 pin connector. The ignition switch in start position sends 12 volts to the start enable relay and then to the clutch switch (xmsn selector if auto), and then to the starter solenoid. Your big clue is that both the starter and the lights go out. This can only happen if the battery ground is defective, or if power to the ign sw or the ign sw itself is defective. Battery connections can be bright and clean, but you cannot see the connection of the battery cable into the lug that bolts onto the battery posts. I had a ground cable lug go bad on my 74 vette. Your next purchase needs to be at least an electrical service manual so you can troubleshoot your system. Your problem is too detailed to fix over this forum and before you pass from this life I assume you'd like to drive the car at least once without it stranding you. :D Good luck.

 

Not trying to be a sitckler, but although the main firewall connector is called C100 it isn't a 100 pin connector. Please forgive me if I'm not reading this correctly and your are referring to another connector, but I don't remember ever seeing a 100 pin connector on a Corvette. If you are referring to C100, I can attest to there being potential problems there. It seems a fellow had C100 disconnected on his car at one time. It was reconnected without the use of di-electric grease or any type of sealant. He had a drainage problem at the driver's side hood latch that caused this connector to get soaked. It does rain here in Britain on occasion! He had no end of ghost like electrical problems as a result.

 

You are correct, its connector C100 and it has 46 pins.

 

This just rescued me from the side of the road!