Stone Cold Dead
 

While removing the alternator to install a new high volume water pump, I accidentally grounded one of the terminals against the cylinder head. I had stupidly neglected to disconnect the battery beforehand :CRY: and now the entire electrical system is dead. The battery still shows a strong charge, but that is it. No lights, horn, instruments and no igntion. I understand that grounding the alternator can destroy it , but does it sound like I fried something else as well? Bear in mind that I still have the Chevy engine in the car and the alternator is a GM 3 wire unit. I have already ordered a new alternator from Summit, but in the meantime (about a week) shouldn't there be some sign of life in the rest of the system? What should I look for first? Any help will be deeply appreciated.

Do you have a fuseable link in your wiring system? Check that or maybe the main wire, where the link would be, for a hard spot where it may have surged. Good luck.

There is a fusible link in the wire to the starter if I remember correctly. I will check it out. Thanks.

Well, I checked the fusible link in the hot line going to the starter and it is fine. So the question now is; can I expect to bolt on my new alternator and problem solved or is there likely to be damage elsewhere? All fuses are ok, no sign of any burned up wires in the engine compartment or behind the dash. Can a shorted out alternator alone halt all power in the rest of the system?

If all of the system is dead, then you have more problems than your alternator. Don't forget the ground side of the system. (It's as important as the possitive side, more so on a fiberglass car!) Start from your battery (since you do have power there) and work your way up to the front. Use one of the cheap light testers to make it easy to see "go or no go" at each point. Concentrate on the common points like ignition switch, fusible links (may be more than one) or even the battery connections.

Thanks for the reply! I checked the battery and the connection at the starter with a voltmeter and both read over 12 volts. The battery negative to frame ground connection is good. I guess like you suggest I'll just have to start tracing wires from the starter forward until I find the fault. I posted my tale of woe on the Unique Owners Forum as well and I'll update both as soon as I (hopefully) track it down.

Buzz,

Good to see you are covering all your bases and resources :3DSMILE:

Good luck.... hope you find it soon.

I did the same thing while replacing the starter selinoid. I found the altinator was the weak link. Replaced it and all was ok.

Have you seen this thread for Backdraft already??http://www.clubcobra.com/forums/show...wiring+diagram

You can check this with a couple of items, a DVOM or a 12V test light.

Connect the negative side of the test device to the frame or engine. Make it a connection that you do not have to worry about as you work ( IE; use a clamp to secure it to the ground ).

Walk the hot side of the device from the battery to all of the connections, make sure there is either 12.8V or a light on during the entire process.

Chances are you will find you blow out a wire or fuse in the system that is major. Once you find the offending wire/fuse, make the repair and continue to check out the system.

As you eliminate sections of the electrical, you can put a piece of red, green or yellow electrical tape on it and keep moving.

It may help to get someone ( wife?? ) to read the DVOM ( Digital Volt meter ) while you are jabbing the probe into parts of the electrical.

Hope this helps.

:D

Double check your fuseable links. It is possible for it to burn within, yet leave the outer insulation intact. Making it appear as though it is OK. These will generally be the first wire in a heavy or main circuit, near where the (+) positive side of the battery is initially attached attached to it. IE: at the starter solenoid, circuit breaker, amp meter other common feed.

Busy day today - hopefully I'll be able to get at it later on. Thanks again for the help - I'll update this evening.

Quick note: on my way through the garage, I grabbed the multimeter and verified the following:

* Full 12 volts to the starter
* 12 volts at both ends of the fusible link connected
to the starter.
* 12 volts at the alternator terminal.

Good frame ground verified at several points. Didn't have time to check any further.

Didn't get a chance to actually work on the car today, but I decided to study the ProDesign manual that came with the wiring harness. To ease my pain tomorrow, I sketched up a schematic based on the info. The wires are numbered & colored as in the manual and the lightning bolts indicate points that a 12V reading has been verified. Question: Do I have the current flows as indicated by the white arrowheads correct? (Note: starter is a GM unit with no external solenoid)

http://www.clubcobra.com/photopost/d..._schematic.jpg

I've done and do a LOT of electrical work, low voltage and high voltage. What I really hate is when you find the problem and of course it's SO easy to explain the malfunction. Why it was a 'piece of cake', others may think, that was SO easy why didn't he just figure that out right away?

Well SURE it's 'easy' AFTER you figure it out! If it's so darn 'easy' why don't we have an answer right now? :LOL: I'll tell you why, because it 'aint THAT easy'!

You'll get it Buzz, and I for one will understand, it took some dam work, I don't care how easy it might appear to be once it's solved! :D

It appears that you will need to gift the car to me, then I will fix it.

It sounds that the battery feeds are okay. All the accessories should be wired through the fusebox. Check the feed wire to the fusebox, it should have a fusible link or circuit breaker. Are there any relays? Do they work? It sounds like your starter/alternator/battery lines are okay, but the rest is dead... everything else "should" be through the fusebox.

Well, I went diggin' and found a couple of things. Firstly, I had a few details wrong in the schematic I interpreted from the directions in the manual, so here is the corrected version:
http://www.clubcobra.com/photopost/d...schematic1.jpg
Then I learned that positive feed to every electrical component except the starter on a car equipped with an ammeter must go through the ammeter and then on to ignition to coil, fusebox, etc.
I decided to run a jumper wire from the downstream end of the fusible link in wire #27 off the starter right to the "BATT" terminal on the alternator. Well hello there - everything (except the bypassed ammeter) worked like a charm. The car fired right up and actually seemed to run a bit smoother than before along with a startlingly crisp response when I blipped the throttle. First conclusion is that the fault exists somewhere between wire #27 and the ammeter since there was no power to ignition or fusebox prior to the jumper. Secondly, this exercise appears to have exposed a weakness in the system somewhere between the fusible link ,ammeter and the alternator because of the very noticable improvement in idle quality and throttle response after the bypass. I also noticed a possible ground issue in my cooling fan circuit as the fans ran intermittently when everything else was working perfectly. Back to the garage to start tearing into that portion of the harness to see the condition of wire #27 and check the ammeter then wires #39, 41 and 25. I'm sure I'll find the problem somewhere in that group. I'll keep updating...Thanks again for all the help.

buzz, check the coonection at the back of your ammeter , is it plug in or nut type , i bet the nuts come loose .

In your diagram it appears that the "labeling" of the respective circuits for the amp gauge is reversed from what it should be. The battery pole should be attached to wire 27 and accessory pole to the switch. Also the arrows on some of your circuits should be reversed to indicate correct current flow. ALL of the current is originating at the solenoid battery connection, goes through the AMP gauge (to be measured) and then to the fuse block and ignition switch to be distributed. If you have solid 12 volts at the back of both poles on the amp gauge and at the fuse panel where 41 attaches and at 24 then I would say your switch is bad. If you only have 12 volts at one side of the AMP gauge then you have a bad gauge. You can have the alternator checked at Orieleys or Kragens for free. I would appear that based on your diagram that all current for the alternator goes through the switch.
Keep us posted. This type of experience really helps you (the owner) understand how electricity is distributed throuout your vehicle. It is very satisfying when you are able to finally anylize and solve the problem.
Let us know what you find.

Rick

Well, it's a lot worse than I had hoped. After pulling the dash, I found power coming in to the ammeter acc. terminal through wire #27 from the starter but no power at the "batt." terminal which feeds wires 25, 39 and 41 connected to the starter, fusebox and alternator respectively. This indicated a fault in the ammeter itself which I bypassed by connecting #27 directly to 25, 39 and 41. Everything (except the ammeter, of course) seemed to come back on line and the car started up and idled beautifully. Since I had installed a new high volume water pump, I decided to let it idle for a while with the fans off to see how fast the temperature came up. Well, I soon realized that either the new pump was doing a mighty fine job or the temp gauge was not working. Unfortunately, it turned out to be the latter case and then when I turned the fans on, they ran for a second and stopped (manual - no thermostat switch). Wiggling the wire bundle connected to the fan switch got them going again but they would stop and start at the slightest touch of the wires. "Ok", I thought; What next? I turned on the headlights and the "tail" fuse in the box promptly sparked and blew leaving me with no taillights but brakelights and headlights work as well as turn signals and hazzards at all corners except the left rear. Horn, dash lights and tach are fine. My first guess (hope?) is maybe a damaged ground wire in the dash harness somewhere. I will try to trace the fault(s) tomorrow and let y'all (we say that down here too, you know) in on what I find. Time for a swim.