Electrical Problem

[SVTCobraLTD]

My car (93 cobra) just got back from the dyno. But while i was in the garage i tried to start it and the battery was real low. I have the new optima battery to replace it but didn't put it in yet. Anyways, i put the battery pack on it to give it a boost to start, put the ground on then the positive side. When i did the pos side it sparked a lot and then stopped. But by the time i went and got in to start it, nothing. So i disconnected the battery pack and tried again, nothing, not even the dinging for the door open. Only thing I can get to work is the interior light above me. But if i turn that one and turn the key to the on position, it turns off. Nothing else in the car works. Any ideas? Or even where to begin to look?
More info can be found at http://www.corral.net/forums/showthread.php?t=879584

SVT

 

[HISSIN50]

I'd start by checking for blown fusible links and fuses. Chances are a link or two was taken out.

Good luck.

 

[SVTCobraLTD]

I'd start by checking for blown fusible links and fuses. Chances are a link or two was taken out.

Good luck.

I don't know that it could be a fuse though. Like I said it tried to start today. I am thinking its either the starter solenoid under the fender or the one on the starter because I tried jumping the starter solenoid with screwdriver and after i took the screwdriver off it kept trying to start. So one of the two is most likely bad. Starter is only like 3k miles old and the starter solenoid only had dyno time.

SVT

 

[HISSIN50]

I don't know that it could be a fuse though. Like I said it tried to start today. I am thinking its either the starter solenoid under the fender or the one on the starter because I tried jumping the starter solenoid with screwdriver and after i took the screwdriver off it kept trying to start. So one of the two is most likely bad. Starter is only like 3k miles old and the starter solenoid only had dyno time.

SVT

I had assumed a spare battery was installed after the reverse hook-up with the jumper.

For the solenoid: if a fusible link for the ignition switch let go, it seems to me this would keep the solenoid from receiving the starter-interlock trigger. With the car in neutral and e-brake applied (you will bypass the safety interlock), try removing the small slide-on (S-terminal) wire on the solenoid and touch it to the battery lug (generally closest the firewall of the two solenoid lugs). If the engine turns over, the solenoid is ok. I'd chase ignition and starter interlock wires and switches.

A semi dead battery can cause a starter solenoid's contacts to latch - that might be what you experienced.

Random thoughts. Good luck.

 

[SVTCobraLTD]

Battery wasn't hooked up backwards. I did try both the semi old battery and new optima battery. Same results with both. When the starter solenoid locked like that, the battery was hooked up and the charger was on and I was getting 13.21 volts at the SS at the time. I will have to try that with the small stud but which side to you touch it too? My SS is hidden in the fender to its not mounted the same way as before.

SVT

 

[MeanMussy]

You have a short to ground some where.

Your battery terminal will spark a little bit when you first hit it w/ the cable. Just from the hood light, and the radio clock, etc. There's a little bit of current being pulled. If it was a HUGE spark, then you may have a short between the battery and the alt, or in one of the always on circuits.

Was the overhead light on at close to it's normal brightness and then it went off when you turned the key on? If so then you have a dead short some where in a key on circuit.

Only thing to do is assume everything is shorted and start eliminating things. You can either hook a battery up and keep discharging it, recharging it and trying again, or you can try a multi-meter w/ a discontinuity tester. Figure out if its an always on or key on circuit. If it's always on, start by taking the cable from the solenoid to the starter off. Then the one from the from the hot side of the soleniod to the alt off. After that I guess you'd have to pull all of your fuses and keep putting them back in until you find the bad circuit.

Electrical problems suck!!

 

[MeanMussy]

Wait a minute.. have you tried the new battery yet? Sounds like it could just be an old worn out battery too.

 

[SVTCobraLTD]

I have a new optima battery there but didn't want to try it because I didn't want to kill a $180 battery. I don't think its as simple as the battery though as the car has been running fine for some time now. The performance started it numerous times on the dyno over and over again. It started slow but started. Battery is bad though. But not bad enough to not start the car.

SVT

 

[MeanMussy]

I have a new optima battery there but didn't want to try it because I didn't want to kill a $180 battery. I don't think its as simple as the battery though as the car has been running fine for some time now. The performance started it numerous times on the dyno over and over again. It started slow but started. Battery is bad though. But not bad enough to not start the car.

SVT

If that's the case, I'd just pull the cable off of the battery, charge it up, check the voltage, hook it up, check the voltage and then start pulling things and checking the voltage until I found what was causing the drop. If it's gone and you have a back up, why not fry the thing..