1979 Bronco starter relay clicks once the lights out

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BroncoStew

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When I first received the bronco it started no problems, twice. It sat for a week I went to start it to keep the battery charged; I heard something click once internal lights, external lights, instrument lights, all died and would not turn on again. I tried to to start again this time no clicking noise, no lights. I started troubleshooting 15 min in to it and magic, lights returned! So I turn the key to standby position brake light energized, turn to start, everything dead check wires-good, battery-good, starter-good, starter relay-good(It cranked only once out of countless tries). I disconnected the starter from the starter relay and turn the key, relay clicks on; when key is released to "run" relay clicks off-as it should-lights stay on and everything. Connect starter and it returns to one click lights out. So I bought a new starter installed it turned the key, click and lights out. Voltage test on the "S" terminal of the starter relay turn the key to start: 12.5V. Twelve was on the alternator, distributor, and starter coil. So figured it was the starter relay, bought a new one...NOPE! Same deal! Ideas?

 

miesk5

96 Bronco 5.0
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yo Stew.

WELCOME!

79 Ford Bronco Wiring Manual by topsig at;

http://www.supermotors.net/registry/24302/83503

Start Ignition in page 5, 10, 11

1979-bronco-f100-through-f350_page_05.jpg

1979-bronco-f100-through-f350_page_10.jpg

1979-bronco-f100-through-f350_page_11.jpg

click to enlarge

I'll have to go through your issues and get back later; so see if you can test for power along the paths. Ensure battery is charged;

Voltage; "...a normal battery that is fully charged produces 12.6 volts, not just 12.0 V. (Remember, when measuring battery voltage, everything in the car should be off, or the battery should be disconnected. Voltage measurements are always "no load" measurements unless the battery is being tested for it's performance under load)..."

Source: by Gordon via miesk5

 

Seabronc

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Sounds like a classic grounding problem.  Remove, clean and re-install all the cable connections from the battery (-) to the engine block and frame.  While you are at it, check the area of the battery (-) cable where it goes into the lugs, if you see any corrosion, replace the cable. Actually that goes for any cable with corrosion at the lugs.

 Also, use sand paper to clean around where the lugs connect to the block and frame.  If you don't have one buy a battery post cleaning tool and clean the posts and the battery lugs.  You can use a little dialectic grease after reattaching the lugs to the engine block and frame to prevent water from corroding the connection.

Repeat with the cables from the battery (+) to the starter.

Other possibilities:

In my experience these are lower probabilities than the cables

The neutral safety switch circuit 

Starter dead spot

Start solenoid

Good luck,

:)>-

 
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BroncoStew

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Thanks to the replies. Greatly appreciated. After the post I disconnected the alt cable all together and inspected the cable there were no visible cracks or anything to indicate the it was being grounded, plus I performed a resistance check and all good there. Next connected to cable to the starter relay turned the key, heard the relay do its thing and tested the voltage 12.34V. Connected it to the starter, took a gander at the negative ground cable and cleaned it up attached it and turn the key nothing...oops the positive end still needed connection-tunnel vision can bite you in the butt. With everything hooked up I turned the key, it cranked-thank God-but no start. I made 7 attemps about 10 seconds each-no joy. Around that time the starter wouldn't crank any more. I left the key in run mode to inpect that I had everything connected. At some point I walk back to the cab and found the red wire running to the ignition was very hot. I also noticed when I would turn on the cab lights the glove box light went out and the cab lights would not energize, same when I placed ignition in standby. I have been anelectronic technician for the past 13years you had me a tech manual and the broken equipment and I'll fix it, but the manuals from auto zone and what is install are not the same. That is the aggravating oh and the fact that the cable manaent and mods the previous owner made were shottie at best.

 
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BroncoStew

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Thank Miesk that'll be very valuable as I take down the wiring to the base starting wiring. And nail in the head Seabronc clean connects are the key to properly operating electronics; thanks buddy.

 

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