Bronco won’t start- need your help!

[Oldtimer]

A little more information would help.
Model year of Bronco? stock harness? or aftermarket replacement (brand)? starter type (stock, PMGR)? alternator (stock, 3G, one wire)?

This is stock power flow from battery to ignition switch. I do not see the black wire at stater relay.



As Paul points out yours may be a PMGR starter?
Where are the other ends of the black and the blue wires?

 

[m_m70]

I’m in the ER waiting room keeping an eye on the significant other and have to jump back-and-forth.

Hope everything is OK Paul!

 

[DirtDonk]

Thanks. She’s doing better. Still not sure what caused the pain, numbness and inability to move her left hand. But so far they haven’t found any signs of any dire problems.
Which in itself, can be either a good, or a bad thing.
Will know more later. But here’s to hoping for a pinched nerve!
Appreciate the comment and concern.

 

[White Knight]

Paul, first… praying things get better for you in the ER. The blue wire is spliced into a black wire coming from dash.

The black with yellow connector goes to the starter

Its a 73 with stock harness, stock starter and alternator. It was running better than ever before I disconnected terminals, removed battery, installed j-screws for new hold down, Re-installed battery and now nothing appreciate all the feedback

 

[m_m70]

And if you haven’t already, I think it was previously mentioned that you can do a couple of easy, quick manual steps to verify that it’s not the starter relay itself. Make sure that it’s in park or neutral, with the brakes set. Then remove the Red w/blue wire from the relay, take a small jumper wire from the battery cable side and just touch it to the small stud where the red and blue wire was.
If it still doesn’t click, you have a bad battery, or a bad new starter relay.

Try this then report back........easy and free

 

[Oldtimer]

Does this red wire also go to starter?

If yes, you don't have a stock starter. . . but this is probably not the issue.

Take test lamp and check for power on black/yellow wire at back of alternator and the yellow wire at the regulator.
They should both have 12v with ignition switch off.

Looking at seabiscuit68's schematic your bronco would have had a fusible link at the starter relay.
Lookig at schematic in post # 21, Power flow is thru fusible link, to dash on black wire, thru ammeter, spliced to taps for headlight switch and ignition switch, then back out to alternator on black/yellow wire.

PO spliced a blue wire to black wire at starter relay, most likely when fusible link turned to smoke.
I would check that splice, and follow the black wire to make sure there is still not a burned section of fusible link.

Link to seabiscuit68 schematics: https://seabiscuit68.tripod.com/

 

[White Knight]

Yes that red is going to starter. I don’t have a yellow wire …. By regulator… do you mean solenoid as I don’t have a regulator. I will follow the black wire to the dash for a fuseable link. Anything I should check at the ignition coil?

 

[Wild horse 75]

If that heavy wire goes down to the starter you don’t have a stock starter. And if you don’t have a regulator on the inner you don’t have a stock alternator.

 

[DirtDonk]

I believe you said earlier, that nothing else on the truck works electrically. Is that still correct?
No headlights, no brake lights, no heater, nothing with the key?
Or does that stuff all work?

It doesn’t hurt to follow along the black wire to the dash, but you won’t find a fusible link anywhere along the line. It’s only at the end of the wire where it mounts to the battery side of the starter relay.
Or was replaced, as suggested earlier.

Can you post up a picture of your alternator?
Maybe another shot just showing the whole engine compartment for us to take a look at?
Obviously this is something simple (theoretically), because it happened only when changing the battery and battery tray.
To do that you wouldn’t normally have the battery cables disconnected from the starter relay or the engine, so again in theory, you didn’t really touch anything that could’ve caused this.
That’s why it’s a mystery and we’re throwing so many questions at you.

 

[Oldtimer]

This connector attaches the alternator harness to the main harness.

Follow the wires toward the engine, they should connect to the alternator;
black/yellow stripe is output from alternator to charge battery
orange connects to field terminal
black/red stripe wire connects to alternator case.

Follow wire toward passenger fender;
black/yellow stripe heads towards dash and connects to a black wire at the ammeter
orange wire ends at connector for voltage regulator
black/red stripe wire is grounded to body by bolt attaching voltage regulator to fender

Can you post some photos of complet engine bay, alternator, starter and passenger fender?

 

[DirtDonk]

Haha… Finally beat you to the punch for once.
But as usual, your post has better pictures with circles and arrows, and a paragraph on the back, describing what each one is. Not to mention good descriptions of the implements of destruction.
As Arlo Guthrie used to say…

 

[White Knight]

Going today to get another solenoid in case the new one was bad. After work, I will start to trace the black wire from solenoid into dash. Headlights, turn signals, hazards, radio…. None will come on. I have an old phone so pics aren’t great but I sure appreciate the consultation.

 

[LUBr LuvR]

I believe you said earlier, that nothing else on the truck works electrically. Is that still correct?
No headlights, no brake lights, no heater, nothing with the key?
Or does that stuff all work?

It doesn’t hurt to follow along the black wire to the dash, but you won’t find a fusible link anywhere along the line. It’s only at the end of the wire where it mounts to the battery side of the starter relay.
Or was replaced, as suggested earlier.
Obviously this is something simple (theoretically), because it happened only when changing the battery and battery tray.

Had a very similar situation recently. Had removed battery, battery tray and starter relay from fender to do some cleaning and rust treatment.

Upon reassembly, had no start or power to anything. Turned out the ring terminal on the fusible link had fractured, and while held in place on the side of the relay, was not making contact. When the nut was loosened, it fell off leaving the ring on the stud. Spliced in a new fusible link, and back on the road.

May not be the same issue, but doesn’t hurt to check all connections and ensure they’re intact.

 

[White Knight]

Will do…. Thanks for the feedback. If I add a fuseable link, what size fuse is recommended?

 

[LUBr LuvR]

The stock one on mine was a 16 gauge.

 

[White Knight]

Something like this?

 

[DirtDonk]

I think you’re missing a very important point that we’re trying to get across to you.
Do a couple of simple tests first, and stop replacing parts!
What happens if your new relay/solenoid is also bad? There was a member on another forum that got six bad starter relays in a row!
You can’t throw parts at a problem. Especially when it’s so simple to test!

Sorry for shouting, but it’s truly a simple five minute test (at the most). Do what we described and save yourself a trip to the auto parts store.
Or if it turns out you do have to go to the auto parts store, at least you’ll know you’re on the right track.
Hell, try the old one before you try a new one. You did keep the old one, correct? Never throw parts away anymore until you’re sure they’re bad.
It’s the other rule right after stop buying new parts to throw it a problem.

If you do need a new fusible link (please inspect and test the old one), I believe the official rating is 14 gauge.
The stock black wire is 10 gauge, and generally a fusible link is two sizes, or four numbers, higher (smaller size) than the wire it’s protecting.

 

[DirtDonk]

A lot has been changed in that engine compartment!
But, like you said, I do still see some of the stock wiring. Not much, but enough to know that it’s probably mostly still stock.
Should make it that much easier to test though.

We have to remember here too, that we can also run into what I call a “coincidental failure“ where something unrelated has given up the ghost.
However, since you confirmed that all powered to the vehicle is lost, there are still only those few key points to look at.
So let’s confirm something here again, and I will reiterate, to stop throwing parts at it. A starter relay does not kill power to the vehicle. An ignition component does not kill power to the vehicle. Heck, even the ignition switch does not kill power to the vehicle!
Only a battery cable, or some fault with the black wire will do it. End of story.

So before you go buying any more parts, pull all the wires off the starter relay and inspect them. After disconnecting the battery, of course.
That’s usually what fries a fusible link anyway. Not disconnecting the battery when you’re working on electrical stuff.

Also, get under the dash and look for the black wire, where it passes through the ammeter loop and make sure that that connection is clean and tight.
If that connection fails, it will kill all power to the vehicle.

 

[White Knight]

Something like this?

Ok I traced the black wire from solenoid back towards dash and found this…. It is spliced into a black wire and a yellow wire should I cut this out and replace with a fuseable link back to solenoid?

 

[ba123]

You need to test and find the problem before doing anything new.

Test that wire like Paul said and then if it fails, do that.