car dead after key cycle

[tonykim]

When I hit the ignition this morning the engine started to turn then stopped and everything went dead. No dome light and no headlights. The battery has 12.7v and all connections are good.

I disconnected the battery for an hour and reconnected it and then the dome light and head lights worked again. I hit the starter and everything went dead again and stays dead.

Is this starter solenoid or ignition switch?

[tonykim]

It got dark and cold so I gave up for this evening.

[tumper93]

Would help to have some info on the car!

[David Pozzi]

If the battery connections truly are good, including grounds, - have the battery load tested.

[tonykim]

sorry. it's a 78 Firebird with a 355 sbc. battery is new, cables are new, starter is new.

[derekf]

Trace it back - when it's dead, where do you have 12v? Do you have 12v at the battery lug on the starter, and/or at the horn relay? What about the output from the horn relay?

[tonykim]

didnt' get to the car until this afternoon. Hooked up the negative cable, verified i had 12v at the starter lug. Also verified that I had no voltage drop between starter lug and + lead at the alternator
and no resistance between negative post and alternator bracket. I opened the driver door and had dome light and just stuck the key in the ignition (didn't turn it) and got the "beep". I turned on the headlights and got out to check and nothing. Got back in and everything was dead again. I went out and still had 12v at the starter lug.

The way this is wired, the positive cable off the battery splits between the large wire that goes to the starter lug and the other wire goes through the firewall just above the passenger side valve cover.

I did a quick check and it initially doesn't look like I have voltage at the fusebox. So perhaps it's a loose connection inside the dash.

Then I had bicycle stuff to work on so I stopped. I have a full vehicle harness from a 77 Espirit on the floor so I am going to trace through it.

Any additional help would be good. The horn relay is inside the dash unlike previous models I presume.

[GrabberGT]

The same thing happened to me on a trip a couple years ago. I traced all the power lines and tore the interior out of the car while on the side of the interstate. While waiting for the tow truck I decided to trace my ground cables and found that my main ground cable was loose and had corrosion on it. It supplied enough power to the car for auxiliary items but when it was time to supply power for starting, it would break the circuit and all power to the car would go. So... check all your grounds again. Remove, clean, tighten properly. Hope this helps.

[tonykim]

thanks much. I will look more at the grounds. I spread my spare firebird harness out on the floor last nite and compared it to the car. the red wire i have coming off the battery terminal is for the aftermarket stereo head unit. after doing more reading i am thinking it's likely i have a bad fusible link at the small wire that also connects to the + lug on the starter.

[tonykim]

As I suspected the car is wired like a 79. It has one fusible link past the starter post and then two more right before the bulkhead connector behind the master cylinder.

The fusible link by the starter doesn't look good (I can see wire on the outlet side) but amazingly I still get voltage there, no resistance to + battery post, and no voltage drop.

When I cycle the key I hear a click and then everything goes dead and there is no power in the fusebox but still power past the link by the starter and i see continuity to the
alternator + outlet.

So tomorrow I will pull the bulkhead connector.

Anyone know where I can buy OEM style fusible links. Searched all over the net and can't find them.

[Heleanor]

Ditch the fusible links and put resettable breaker in its place. They are available at most auto stores for high current devices.