1974 Eldorado Completely Dead

[caddydaddy1960]

Hello folks,

I have a problem with my 1974 Eldorado convertible that has me stumped.  The vehicle is low milage (43,000) and is in excellent shape.  I recently replaced the 7 year old battery and had the charging system checked.  It was running and starting fine with the new battery.  After just driving it a few days ago, I went to take it to the gas station to top off the tank for winter storage and found it completely dead.  No lights, nothing.  I hooked up the battery charger and it told me the battery was fully charged.  I did a quick inspection and found nothing, no loose cables or wires.  Any guesses as to where I should start looking and checking?

Many thanks,

Michael Heinz, Director
West Michigan CLC

[Dave Shepherd]

Start with basics, clean and check both cables, look closely at the ground cable connection on the engine or wherever it is grounded.

[V63]

An important thing to remember about 1974 models is they were equipped with a Seatbelt starter interlock. Requiring the seatbelt to be connected before the starter would be engaged. There is a bypass with a red button on the left firewall.

All said...  your problem seems battery cable or connections.

[wrench]

Start with basics, clean and check both cables, look closely at the ground cable connection on the engine or wherever it is grounded.

^ This is the place to start

[Caddyholic]

I have had side post battery terminals look good but are corroded on the inside of the cover and not make connection to the cable.

[35-709]

Check your fusible links down by the starter --- see the shop manual.

[TJ Hopland]

The layout is the positive battery cable goes directly to the starter solenoid which is on the side of the starter.    Stacked on the same terminal is a single ring lug that has the 3 fusible link wires coming off it.    Link 1 goes direct to the headlight switch for the headlights themselves only.   Link 2 goes to half the fuse box for the things that are always on.   Link 3 goes to the ignition switch that then feeds the other half of the fuse box for the things that come on with the key. 

Knowing all that should help you troubleshoot.  If its everything then its between the battery and starter unless something pretty major happened to blow all 3 links suddenly at the same time.  If the headlights work but nothing else that tells us something.  If say the brake lights and lighter work that tells us something. 

One thing I will note here is a 73 has a 6 pin connector about 18" up from the starter that has 5 wires in it including the 3 fusible link wire.   The other 2 are the S wire that engages the starter and the I wire to the coil.   The connector is low enough that it can pick up road grime and gets near the exhaust so if at some point the starter got changed and they didn't get the harness tied back into its original route it could hit the exhaust and melt.   Not sure when they got rid of that connector so there is a chance a 74 doesn't have one but if that got damaged or disconnected the whole car could easily be dead.

[James Landi]

Lots of good advice... HOWEVER,  I'd start with Jim's suggestion.  I've had battery cable insulation looking brand new, but found the actual wire had turned to white dust.  Depending on your level of understanding of electricity, using a multimeter gauge is a relatively easy way to check for toasted and roasted battery cables internal wire.  It involves checking for continuity between each of the battery posts and their respective distinations --- one at the starter and one at the ground connection.  With nothing functioning, there's a strong likelihood that your meter will read 125 volts between one of those connections.  Hope this helps, James

[MaR]

Here is what my negative cable from my '74 Eldorado looked like on the inside. It look fine from the outside.

[caddydaddy1960]

Thank you gentlemen for all of your helpful advice.  Once I recover from my recent cataract surgeries and can see properly again, I will start following up on some of these excellent suggestions.  When I find the problem, I'll post what I found.

Thanks,

Michael

[Cadillacdave]

Not sure if you have the small side post terminals but they seem to corrode on the inside and not make a good connection. Get a small steel brush, like a tooth brush. Remove each cable from the battery, and simply clean each bolt with the steel brush. This usually will correct the problem if it is not making a good connection, which seems to be the underlying problem here. As others have suggested, you could also replace both cables, bit cleaning them may be simpler. Good luck!

[wheikkila]

Cleaning won't help that cable. Time to replace it. I would replace both and save myself the trouble later.
                   Thanks Wayne 

[signart]

Cleaning won't help that cable. Time to replace it. I would replace both and save myself the trouble later.
                   Thanks Wayne

Yes change the cables. You would have to remove the rubber insulator from the connector and separate the layers to properly clean, and that would be good for an emergency short term solution.