Electrical issue - no power to lights or instruments when ACC or On

[crutch]

When the key is in Off position I get power to front, rear and marker lights and to the instrument cluster however when I switch to "ACC" or "On" I get no lights to any of these circuits anymore.

One thing to note, In the Off position when I turn hazards on I get the 2 static lights in the instrument cluster but no blinking and no lights to any of the tail or marker lights. The turn signal is not working either in ACC or ON.

Any thoughts on where to start?

 

[Viperwolf1]

Check the grounds at the lights.

 

[crutch]

With the ignition in Off position and the headlight switch on I get lights around the whole truck and instrument panel. It's only when I turn On or to ACC when everything turns off? Could this still be a ground when the lights work when ignition is off? I'm going to get new flashers to see if that corrects hazard and turn signal but not sure about the On and ACC situation.

 

[Steve83]

Don't you think it would help us to help YOU if we knew SOMETHING about the truck? Like the year, at the very least? A full list of equipment (factory & aftermarket), repairs, damage, mods, & non-original parts would be even better.

 

[DirtDonk]

Original wiring, or an aftermarket harness?
Have you had the Bronco for some time now, or is it new to you?

As Steve alluded to, this is just an unusual enough problem that we'll need to know what all might be causing it. Granted, grounding issues are rampant with EB's, but yours is an unusual case even for these things!

Paul

 

[crutch]

Ahh yes good point. I've lost my mind already staring at schematics and racking my brain. It's a '72 with the original harness. I've only had it a few months and stripped everything apart except for the wiring to do some body work and now putting it back together. The fuse panel was all rusted out so I assumed some of my instrument panel problems were caused by the old fuse panel so I replaced it with a centech fuse box but no luck. I have double checked the wiring and think it's correct. The ignition switch is new and I'm getting 12v from the ignition switch in the on position but no lights or instrument panel in "On". I am definitely a newbie so could be something I'm overlooking. Thanks for the help!

 

[DirtDonk]

It's a '72 with the original harness. I've only had it a few months and stripped everything apart except for the wiring to do some body work and now putting it back together.

Did you make sure to replace (or make sure you had one in the first place) the grounding bond between the battery and body? This would have been part of the main cable on an original negative cable, or a separate "pigtail" on a new aftermarket replacement.
The main cable goes to the engine block obviously, but not so obvious sometimes is that the body needs it's own ground so all the rest of the stuff can work.
Now after 43 years, your body panels are not the most direct ground path anymore, so even adding more cables/wires/straps bonding the different sections of body together is not exactly a bad idea.

Being new-ish to vehicle electrics, you might not automatically have thought of this.
So for starters, just let us know if there is a ground wire from the battery negative to some part of the body, and we can go from there.

The fuse panel was all rusted out so I assumed some of my instrument panel problems were caused by the old fuse panel so I replaced it with a centech fuse box but no luck.

Rust is a common issue for our old fuse panels even if the truck was a CA vehicle all it's life.
But changing that out leaves lots of room for error. Good for you to have taken that large leap to get rid of the old stuff though.
Which Centech part did you use, and does it have separate busses for "always hot" and "switched hot" power circuits?

The ignition switch is new and I'm getting 12v from the ignition switch in the on position but no lights or instrument panel in "On".

Just to be sure, your large Black w/green stripe wire is still connected to the center stud of the ignition switch, correct? And just so you know for sure, this is NOT a ground wire. It's the main wire that feeds all the keyed accessories, including those protected by the fuse panel.

As you may know, the light circuits are not handled through the ignition switch. They're powered all the time directly from the battery through the large Black w/red stripe wire (can be just all Black for a '72 though) and the headlight switch.
Only the instrument lights are protected by the little tiny fuse (in the old panel) while all the main lights are protected by an auto-resetting circuit breaker built into the light switch itself.

If you don't have a good ground between the body and the battery, and the individual body panels and each other (spot welds are no longer a guaranteed connection after those 43 years), the ground electrons (not the proper terminology, but you get the point?) for the lights or other accessories might be hunting for a new path and finding that path through the ignition switch circuits somehow.
Might be a short-circuit in the wiring connections to the new fuse panel. Might be lack of grounding from the battery to the body, or it might be none of the above.

Got pics of under the hood? Got pics of under the dash too by any chance?
And speaking of that large Black wire... Your main power into the cab from the battery (while the engine is not running) is the large gauge Black wire attached to the starter relay/solenoid in the engine compartment. The main power source with the engine running is the alternator. Both use the same Black wire. DC electricity will flow in whichever direction the more powerful source is. So the battery's 12.5 or so volts powers everything until the alternator's 14.5 or so volts comes into play.

In the middle of this is a push/bullet connector just behind the ammeter gauge of the cluster. If this connection is weak, rusty or disconnected, you will have BIG problems. Usually nothing works at all if it's disconnected, so that's probably not your issue. But if it's rusty or loose enough, it could easily cause all sorts of trouble.
So you might as well check that connection right away. Should be a Black 10ga wire with a yellow stripe, just behind the dash on the left. Check it out and see what you see.

That's all I've got for now. Because you've done so much in the way of modifying your stock setup (new fuse panel mainly) you may need to dig deeper into what's been changed or what's not quite right. Like a bad solder joint or shorted connection, or missing ground, or whatever.

Good luck.

Paul

 

[crutch]

Did you make sure to replace (or make sure you had one in the first place) the grounding bond between the battery and body? This would have been part of the main cable on an original negative cable, or a separate "pigtail" on a new aftermarket replacement.
The main cable goes to the engine block obviously, but not so obvious sometimes is that the body needs it's own ground so all the rest of the stuff can work.
Now after 43 years, your body panels are not the most direct ground path anymore, so even adding more cables/wires/straps bonding the different sections of body together is not exactly a bad idea.

Being new-ish to vehicle electrics, you might not automatically have thought of this.
So for starters, just let us know if there is a ground wire from the battery negative to some part of the body, and we can go from there.

I have not pulled the motor so this is an area that I haven't touched but looks like there is a heavy gauge ground wires going from the - terminal of battery and from the solenoid to the engine block but nothing tying into the chassis that I can see.

Rust is a common issue for our old fuse panels even if the truck was a CA vehicle all it's life.
But changing that out leaves lots of room for error. Good for you to have taken that large leap to get rid of the old stuff though.
Which Centech part did you use, and does it have separate busses for "always hot" and "switched hot" power circuits?

This is the fuse panel I picked up. Centech PDP-3 Mini Fuse Panel. It does have separate buses for Battery, ACC and Ignition. I don't think the ignition switch is used for anything on the bronco so I just leveraged this section for the Blue-Red 2A F-2 Fuse.

Just to be sure, your large Black w/green stripe wire is still connected to the center stud of the ignition switch, correct? And just so you know for sure, this is NOT a ground wire. It's the main wire that feeds all the keyed accessories, including those protected by the fuse panel.

I used a voltmeter between these connections and chassis ground to verify the 12V when in "On" position at the center stud of ignition switch (Black w/ green), into the fuse holder and then output to the O-Y and Brown wires (F-1,F-5). Note: also connected to the ignition stud is a red wire which according to schematic is going to some ambient sensor switch and I also have another wire going to my voltmeter from this stud.

As you may know, the light circuits are not handled through the ignition switch. They're powered all the time directly from the battery through the large Black w/red stripe wire (can be just all Black for a '72 though) and the headlight switch.
Only the instrument lights are protected by the little tiny fuse (in the old panel) while all the main lights are protected by an auto-resetting circuit breaker built into the light switch itself.

Thanks for clarifying this, I could tell it was separate but wasn't quite sure where so makes sense its in the light switch.

If you don't have a good ground between the body and the battery, and the individual body panels and each other (spot welds are no longer a guaranteed connection after those 43 years), the ground electrons (not the proper terminology, but you get the point?) for the lights or other accessories might be hunting for a new path and finding that path through the ignition switch circuits somehow.
Might be a short-circuit in the wiring connections to the new fuse panel. Might be lack of grounding from the battery to the body, or it might be none of the above.

Got pics of under the hood? Got pics of under the dash too by any chance?
And speaking of that large Black wire... Your main power into the cab from the battery (while the engine is not running) is the large gauge Black wire attached to the starter relay/solenoid in the engine compartment. The main power source with the engine running is the alternator. Both use the same Black wire. DC electricity will flow in whichever direction the more powerful source is. So the battery's 12.5 or so volts powers everything until the alternator's 14.5 or so volts comes into play.

I'll get some pics today.

In the middle of this is a push/bullet connector just behind the ammeter gauge of the cluster. If this connection is weak, rusty or disconnected, you will have BIG problems. Usually nothing works at all if it's disconnected, so that's probably not your issue. But if it's rusty or loose enough, it could easily cause all sorts of trouble.
So you might as well check that connection right away. Should be a Black 10ga wire with a yellow stripe, just behind the dash on the left. Check it out and see what you see.

I've checked this bullet connector and tried to clean it up a bit and seems like good connection. BTW, any little tricks you have in cleaning these old terminals in various places?

That's all I've got for now. Because you've done so much in the way of modifying your stock setup (new fuse panel mainly) you may need to dig deeper into what's been changed or what's not quite right. Like a bad solder joint or shorted connection, or missing ground, or whatever.

Good luck.

Paul

Thanks for all the recommendations. It sounds like I need to get some ground connections between the battery and the actual chassis not just the engine block. Any particular strategy on this or just get a low gauge cable and connect battery to the engine bay somewhere?

I'll start there I guess and also pick up a couple new flashers to see if the hazards work at least when in the ignition "Off" position.

Thanks!

 

[crutch]

Here are a few pics. In the last one I added a ground cable from the battery terminal to the fender well and made sure to grind off a spot for bare metal connection. Still have same issue when I turn ignition switch to "On". I did replace the hazard flasher and now I get hazards with ignition in "Off" however only front and rear lights flash, not the markers. Not sure if that's how they should work or not.

One other thing, when I start up the truck, the fuel and oil pressure gauges give no reading and the temperature slowly goes all the way to the highest temp. The previous gauge was all busted though so not sure if these ever worked.

 

[Steve83]

The bare steel will corrode rapidly; I recommend adding a little electrical grease there before it goes bad:



In the section of this diagram that shows the relay & battery, try to copy the frame ground where the cable is labelled F, E, D:

 

[DirtDonk]

The new large cable from the battery to the body is overkill, but that's not bad. We like overkill sometimes! The Yellow "pigtail" with the crimp connector already on the end could have been used as well.

The fender is just OK to use. Although that's where Ford grounded the body originally, it's not the best for overall performance anymore. I would leave it, but add another one between the back of the engine and the firewall. You can use a 10ga wire, or even one of those pre-made braided straps to get the job done.
I'm guessing this alone won't fix your issues, but it's a big help with keeping the electrical system healthy overall. And it's what all the manufacturers normally do anyway, so it's definitely not overkill.

In answer to your question about the side-marker lights, they do NOT blink with the flashers. Some have converted them to do that, but they did not blink from the factory.
So it sounds like you're good to go with the flashers.

On the back of the new fuse panel, what color wire is that on the "IGN" stud? And was it connected to the original fuse panel, or is it something you ran from somewhere else?

Paul

 

[crutch]

The new large cable from the battery to the body is overkill, but that's not bad. We like overkill sometimes! The Yellow "pigtail" with the crimp connector already on the end could have been used as well.

The fender is just OK to use. Although that's where Ford grounded the body originally, it's not the best for overall performance anymore. I would leave it, but add another one between the back of the engine and the firewall. You can use a 10ga wire, or even one of those pre-made braided straps to get the job done.
I'm guessing this alone won't fix your issues, but it's a big help with keeping the electrical system healthy overall. And it's what all the manufacturers normally do anyway, so it's definitely not overkill.

In answer to your question about the side-marker lights, they do NOT blink with the flashers. Some have converted them to do that, but they did not blink from the factory.
So it sounds like you're good to go with the flashers.

On the back of the new fuse panel, what color wire is that on the "IGN" stud? And was it connected to the original fuse panel, or is it something you ran from somewhere else?

Paul

Thanks Steve and Paul. I'm going to work on some more grounding.

That wire on the "IGN" stud is the Blue-Red wire which is fuse F-2 from the original fuse panel (2A) and goes to instrument cluster lights.

 

[crutch]

I've got a couple other pieces to the puzzle I figured I would share as I don't think this is expected operation but not quite sure what they mean.

I noticed that when I run the engine at idle the voltage doesn't increase at all at the battery terminals. When I rev the engine, the voltage will increase to just a little over 13V. At idle shouldn't the voltage be higher?

It also seems that the voltage is draining because now my battery is down to an even 12Volts where it was 12.4V last night. I used a test light in series between the battery terminal and the battery cable with ignition in "Off" and didn't get any light. Note: this is a new battery.

When I turn the ignition to "On", the voltage at the battery drops to about 11.7V. I checked the voltage regulator and the "A" and the "S" wire are both at 11.7V as well.

Does this additional information shed any light on the situation? I'm thinking I should take the alternator to O'riley's to test but given the drop in voltage and lights don't work when in "On" before starting does this imply that I still have a wiring issue?

Thanks as always for helping step me through this.

 

[DirtDonk]

It might be worth having it tested, but look for a wiring fault first.
You're correct that it should actually show approx. 14.5v when the engine is running, so something is keeping it from doing it's full job. Whether it's a wiring fault or internal alternator fault is hard to tell at this point.

Of course, since finding wiring issues is so much drama sometimes, perhaps just taking it over to have it bench tested first is not such a bad idea after all. That way you can know whether you just need a new alternator, a new voltage regulator, or need to spend some time with the wiring.

The fact that you have full battery voltage (in this case, just 11.7) at the voltage regulator is a good thing. This means that the wires and connections between the ignition switch and regulator ("S" Green w/red), and the main battery supply wire to the regulator ("A" Yellow) are good.
I don't know what the Orange "F" wire should read at these times, but it's possible the regulator is sending the wrong signal through it to the alternator.

You can test this theory by "full fielding" the Orange wire. Wait for one of the experts, but I believe all this entails is jumping the A wire to the F wire (temporarily only) and watching the voltage at the output at the battery again.
If it jumps to 14.5 or above, then the alternator is good, but either the regulator and/or the Orange field wire are bad.

Hard to say whether you have a drain at this point or not. Sounds like just the normal loss at a battery. You say it's new, but a freshly charged battery that's reading say, about 12.5 to 13 volts, will slowly lose some of that down to the low 12's over a period of just a couple of hours.
The fact that it's going below 12 overnight though, makes something suspect. Either your volt-meter is reading low, or you have a drain above and beyond normal.

The test light test makes a drain seem unlikely at this point.
Keep at it. Hopefully it's just a simple matter of needing a new voltage regulator.

Paul

 

[crutch]

Just took the alternator in and tested it. The voltage range was good but it failed the voltage ripple test. I'm thinking this is a good opportunity (excuse) to pick up one of the 3G one wire alternators from you Paul.

 

[DirtDonk]

Hah! Happy to oblige of course. Thanks.

I'm not even sure what a ripple test is, but if it fails anything, it's a good excus... er, I mean "reason" to change it out.
As you figured too, nothing wrong with going to a simpler, higher output version at the same time either.

It'll simplify the under-hood wiring too, as you'll remove the external voltage regulator at the same time. Won't need any of the wires either, so can use the old Green wire for any future switched power needs.
Just remember to buy the uprated charge cable and fuse (unless you're going to build your own) here: http://www.wildhorses4x4.com/product/Battery_Charge_Cable_AMG_fused

The new setup, along with making sure that the big battery cables you already have are clean and tight, should fix the no-charge issue. But it's not likely to do anything for the whole Key-Off/On dilemma with the lights and such.

Any progress on that front yet?
Try disconnecting that Blue w/red wire from the "IGN" post at the back of the fuse panel. I have a feeling it's not supposed to be there. Remember that this circuit is not powered by the key, but by the light switch. It merely has to go in one side of the fuse and out the other. This may be what you have of course, since the IGN stud isn't really doing anything else. But just in case it's getting feedback from other sources in the panel, you can at least isolate it as a test.
Pull the wire and tape it up temporarily to keep it from shorting against something, then try all the functions again.

Good luck.

Paul

 

[crutch]

Great, I also picked up the upgraded charge cable and fuse so will get that in later this week.

Any progress on that front yet?
Try disconnecting that Blue w/red wire from the "IGN" post at the back of the fuse panel. I have a feeling it's not supposed to be there. Remember that this circuit is not powered by the key, but by the light switch. It merely has to go in one side of the fuse and out the other. This may be what you have of course, since the IGN stud isn't really doing anything else. But just in case it's getting feedback from other sources in the panel, you can at least isolate it as a test.
Pull the wire and tape it up temporarily to keep it from shorting against something, then try all the functions again.

Good luck.

Paul

I think I made a little progress; after I added that ground cable from the back of engine block to firewall my lights started working in the key-On position but still not the flashers or turn signals. When I encountered the lower voltage at the battery and the charging issue I figured I would focus on that issue first. Once I get the alternator back in I'll give your recommendation a try on the Blue w/ red wire on the "IGN" post. Good idea to at least isolate this. I've been reading more threads on grounding and I'm going to also add some additional ground from the instrument cluster to the firewall. Since my dash is entirely off I likely am not getting a good ground on the cluster for the gauges.

I'll let you know how it goes later this week. Thanks!

 

[DirtDonk]

Oh yeah, that's an issue for sure. While things like the ignition switch and headlight switch don't need to be grounded to work, pretty much everything else does!
Definitely add that wire, but remove the Blue wire (at least temporarily) from the panel, and see what transpires.

Paul

 

[Steve83]

This caption describes full-fielding the 1G:



This diagram shows how a 3G should be wired:



DO NOT try to keep the factory ammeter with any higher-output alternator:



This caption describes cluster grounding:

 

[crutch]

Great, thanks Steve! I really like the connectors you added to the instrument cluster.