No electrical power!

B

bfdinardo

Member
I have a 1956 Fairlane and she died while driving the other day. Total loss of electronics. No interior light, no idiot lights when ignition is in run prior to turning the key to start it, and obviously nothing happens when I do attempt to start the car. I don't hear a click of the starter relay or anything as well. The battery is less than 2 months old and the voltmeter shows 12.5 volts so it's good. I noticed the battery ground to the engine block was just a hair loose but still plenty connected and I tightened that up with no affect. Any ideas what I should check next? I know the only fuse is for the headlight box and that is not blown. Thanks in advance for any help!

Brian
 
A start: Check for 12V on the terminal of the starter solenoid that the battery cable attaches with the other lead of the volt meter on engine ground. I think you won't have voltage there since the lights don't work. If it is there, go to the "BAT" terminal of the ignition switch and check for 12 V. If you have 12v there, I would look hard at the ignition switch.
 
Also.... make sure there's a healthy sized ground wire with good connections from the engine block to the body of the car. Sometimes found on the back side of the engine block to the firewall.
Many folks don't know they exist and they're easily neglected.
If it's fried or loose the only thing on the car that's officially grounded to the battery is the block & transmission, and not much of anything attached to the body will work right, if at all.

second photo... The wire gauge/size of this one was apparently too small.
It had been so hot it overheated the copper and trashed the insulation, which all fell off.
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Great advice so far gents. I checked with a voltmeter between the engine ground and the starter relay terminal that the positive battery terminal connects to and got 12.5V. Good there. I checked the ground cable from the engine block to the firewall. It was connected tight but not in the greatest of shapes. No insulation, plenty of old grease covering it so I'll be replacing that tomorrow. As for the third recommendation, of checking the "BAT" terminal of the ignition switch, how do I know which terminal that is? I crawled under the dash and looked at the back of the key ignition and saw a terminal for ACC, ST, and IGN, and couldn't see the final 4th terminal letters. Is it safe to assume that one is the BAT? Any other tests, like should I test the voltage across the starter relay while someone tries to turn the car over? I assume this is the same thing as simply listening for the relay to close during starting. Thanks.
 
I think it is safe to say the 4th terminal is the Batt terminal. It should be hot all the time.
Do the headlights work?
 
Grumpy Rick said:
The engine to body ground on my 55 T-Bird is an inch wide flat braided wire, no insulation.
Click to expand...
1 inch wide? No wonder this little one cooked. And since it's a ground wire insulation is not necessary.

bfdinardo said:
... As for the third recommendation, of checking the "BAT" terminal of the ignition switch, how do I know which terminal that is? ...
Click to expand...

paul2748 said:
I think the bat terminal has a yellow wire on it
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Yes, the yellow wire on the ignition switch is the 'bat' wire. Looking at the attached wiring diagram, it comes from the Headlight switch 'bat' terminal. There are also two slightly heavier gauge yellow wires on the Headlight switch "Bat" terminal. Those two go forward thru the firewall, one comes from the 'bat' terminal of the starter solenoid, the other goes to the voltage regulator. (IIRC the yellow 'bat' wire to the voltage regulator on my '55 may actually be connected at the starter solenoid instead of on the headlight switch, the function is the same.)

Double check the yellow wires that run from the starter solenoid to the headlight switch and then to the ignition switch. It's possible the connections on the 'bat' terminal of the Headlight switch have a problem. The power for most everything but the starter is connected to/thru that terminal.

wiring diagram at this link...
http://www.oldcarmanualproject.com/tOCMP/wiring/5765wiring%20diagrams/Ford/MWire5765-195.jpg

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The battery terminal of the ignition switch has the big yellow wire on it. That wire originates at the battery side of the ignition solenoid. Could be that this connection is corroded, needs to be taken apart and cleaned. I have a large star washer on mine so that when you tighten the nut on that terminal, the star washer bites into the ring tongue terminal of the yellow wire. If that is good and there is still no juice, the problem is downstream at the starter switch. Maybe corroded terminal there or switch bad?
 
I was trying not to use my dusty '55 project as some sort of example because too many previous folks have had their hands in it. But in reality maybe that's the better example.
You'll need to follow the larger yellow wire(s) from the '+' battery cable side of the starter solenoid that go thru the firewall. See what they are actually attached to under the dash, and if the Ign and Light switches are working properly.
A voltmeter or 12v test light to the various terminals will let you know. The body ground wire to the block should be cleaned/repaired/replaced first.

I found two large yellow wires going from the starter solenoid to the 'spaghetti' side of the dashboard. One went directly to the headlight switch. The other was attached to/thru a thermal circuit breaker and then to the ignition switch. The output side of that circuit breaker also went to other wires, another circuit breaker, and more electrical items. Given the condition of the original wiring and some highly questionable 'repairs', I'm glad I had been carrying 2 fire extinguishers in the car.

Moral of the story:
You'll likely need to spend some time under the dashboard trouble-shooting & figuring things out.
A well folded over blanket to lay on makes the floor slightly less uncomfortable, and taking the seat out can help too.
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Thank you all for your help. I crawled under the dash and did some "poking around" with the voltmeter. The headlight fuse/switch assy had a loose connection on it so once things were cleaned off and tightened up, all the lights returned! Through your recommendation I also replaced a very sketchy engine to firewall ground wire with a nice new, insulated thick 5 strand copper wire for added robustness. All is well!

Brian
 
Thank You for the follow-up! I'm glad things are working now. What did you do to restore power to the ignition switched circuits?
 
bfdinardo said:
Just cleaned off some slightly corroded connections!
Click to expand...
Great news!!

In the 'It doesn't hurt to check everything' category, your reply reminded me...

I've got a neighbor who bought a T-Bird over 20 yrs ago that during the last couple years had developed a worsening & intermittent starting problem. The electrical on the car all seemed to work fine but occasionally the solenoid would only click and the starter wouldn't turn. It drove him crazy trying to find the problem until he discovered the previous owner had sprayed silver paint on the battery & starter cable lugs before installing them on the solenoid, so they'd look shiny. :o
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dmsfrr said:
the previous owner had sprayed silver paint on the battery & starter cable lugs before installing them on the solenoid, so they'd look shiny.
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I can appreciate his attempt at detail work, but when electrical continuity is required between metal connections, you can't use paint unless you have installed "star" washers. For something as critical as the battery cable connections to anything, I recommend at minimum, thorough cleaning with wire brush (or maybe even run tap and tie set on the threads) then use high dielectric silicon compound on the threads. NO paint, and also add star washers here. Sorry, it won't stay shiny forever, but that is the nature of the environment upon metals. You just have to do the best you can.
 
I was in auto-tech school 1971-72. My instructor that taught electrical told us something I've never forgot. You want all electrical connections just like your woman, clean and tight. Sorry if that's a little vulgar but I still kinda smirk when I think of it.
 
I always coat all chassis and body connections (bare metal) with a light coat of white grease and use a star waster. Starter solenoid too! If it is exposed to mean ol mother nature it gets the treatment.
 
I don't know if any of you ever heard of "Duxseal". It is a product that is used in the refrigeration/air conditioning industry that is kinda like silly putty. They use it to seal gaps in ductwork, seal around refrigeration lines where the lines penetrate the building wall, etc. Well, I invented a new use for this stuff years ago. After solenoid posts are cleaned and re-assembled, pull off a glob of Duxseal big enough to shape around the terminal post and nut (shape it with fingers) then smash it all around the post tight. It will stay on there for many years and does a remarkable job of preserving the metal and keeping it sealed off from the environment. If you ever need to service the terminal, just take a screwdriver and pry off the duxseal. Duxseal does harden somewhat over the years so it is not re-usable if too dried out. I always just use a new piece. I also use duxseal to seal around the threads of miscellaneous bolts exposed to water splashing the undercarriage (fender, splash pans, etc).
 
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