3 electrical gremlin questions

[DC_Gearhead]

I’m all painted and ready to start driving to work but I’m having a couple of electrical issues I’d love some help trouble shooting.

1 - gas gauge - gauge shows just above “E”. New sending unit installed 4 or 5 years ago but sat until now. New gauge installed in cluster. It’s getting the 5.5v and pegs the gauge when grounded. Checked ground wire and it works at tank. Cluster is grounded well too. Wife said when I unplug the sending unit the gauge dropped a little and when I plugged back in it went up a little to where it was. Any ideas? I’m thinking the sending unit could be stuck or bad. Any experienced troubleshooting ideas?

2 - emergency flasher keeps clicking after turning off. It also randomly starts clicking when I use turn signals. I have the LED flashes installed on both turn signals and emergency flashers. If I unplug the emergency flasher everything works fine except the emergency flashers of course. All new light buckets, led bulbs, and led flashers. Any ideas?

3 - parking lights - turn signals work but when I pull the headlight knob half way the parking lights don’t come on. They used to. I checked voltage at the light buckets and no +12v voltage. Good ground. New 1157 led bulbs, new buckets and new headlight switch. Am I remembering correctly that the 1/2 pull should turn on the parking lights?


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[EPB72]

#! check resistence across sending unit terminals 10 -70 ohms 10 ish being full 70ish being empty,#2 LED s can be hit or miss ?? #3 yes park lights come on at first notch do the tail and license plate light come on .. go back and make all fuses are ok,, aftermarket or OE wiring harness ,,

 

[DirtDonk]

1 - gas gauge - gauge shows just above “E”. New sending unit installed 4 or 5 years ago but sat until now. New gauge installed in cluster. It’s getting the 5.5v and pegs the gauge when grounded. Checked ground wire and it works at tank. Cluster is grounded well too. Wife said when I unplug the sending unit the gauge dropped a little and when I plugged back in it went up a little to where it was. Any ideas? I’m thinking the sending unit could be stuck or bad. Any experienced troubleshooting ideas?

From your description you’ve already done the testing.
Either the sending unit is faulty or jammed up, or your tank is empty.

2 - emergency flasher keeps clicking after turning off. It also randomly starts clicking when I use turn signals. I have the LED flashes installed on both turn signals and emergency flashers. If I unplug the emergency flasher everything works fine except the emergency flashers of course. All new light buckets, led bulbs, and led flashers. Any ideas?

You have two things that I can think of that might be going on.
You’re using LED lamps, which are polarity sensitive, and you’ve changed to new buckets.
The new buckets are going to need testing to make sure the wires are not reversed.
They often are nowadays. More often than not in fact.

3 - parking lights - turn signals work but when I pull the headlight knob half way the parking lights don’t come on. They used to. I checked voltage at the light buckets and no +12v voltage. Good ground. New 1157 led bulbs, new buckets and new headlight switch. Am I remembering correctly that the 1/2 pull should turn on the parking lights?

You will have to check to switch itself sounds like.
Because it’s new, it could easily be defective.
Either pull it out and check it with an ohm meter, or if you can get up underneath there and stick a probe in the output wire for the running lamps, check to see if power is coming out.
If not, you would seem to have a defective switch.

 

[DC_Gearhead]

#! check resistence across sending unit terminals 10 -70 ohms 10 ish being full 70ish being empty,#2 LED s can be hit or miss ?? #3 yes park lights come on at first notch do the tail and license plate light come on .. go back and make all fuses are ok,, aftermarket or OE wiring harness ,,

Good to know on the ohms. I’ll check. I have a full tank so should be around 10. Otherwise it’s the sending unit.

Fuses are good. Did see that I popped the 14a fuse and I’m not sure why but after replacing I hasn’t happened again. Could be a clue. Yes, tail and license plate lights work property. OE wiring harness with no crazy splices from POs or damaged wires that I’ve found. In great shape.


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[DC_Gearhead]

From your description you’ve already done the testing.
Either the sending unit is faulty or jammed up, or your tank is empty.

You have two things that I can think of that might be going on.
You’re using LED lamps, which are polarity sensitive, and you’ve changed to new buckets.
The new buckets are going to need testing to make sure the wires are not reversed.
They often are nowadays. More often than not in fact.

You will have to check to switch itself sounds like.
Because it’s new, it could easily be defective.
Either pull it out and check it with an ohm meter, or if you can get up underneath there and stick a probe in the output wire for the running lamps, check to see if power is coming out.
If not, you would seem to have a defective switch.

Checking ohms will confirm the sending unit. I just filled the tank otherwise I’d just pop it off to see if it works.

Good to know on the light buckets possibly being reversed. I’ll check that, but wouldn’t it pop fuses every time they got a positive charge since the bucket is grounded?

I hate messing with that light switch. It’s one of the few things I get annoyed with. Haha. I have the diagram somewhere for what feeds do what on the switch. I’ll test it and try not to throw any tools in frustration.

One weird thing with the hazards that I figure could be relevant. If I switch the hazards on and then turn them off, the flasher keeps going like I said, but when I turn the ignition off the flasher stops. Then it starts again when I turn the ignition back on. Since the hazards should always be energized this seems important.


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[DirtDonk]

It’s funny, but the flasher circuits and how they relate to the turn signals and brake lights is one of the things I understand the least!

 

[DirtDonk]

Good to know on the light buckets possibly being reversed. I’ll check that, but wouldn’t it pop fuses every time they got a positive charge since the bucket is grounded?

Not necessarily. The wires that are reversed are both positive. It’s just that LED lamps are polarity sensitive, so might be messing with things. I don’t know this is the case, or that it could even happen. I just think it’s worth checking.

 

[DC_Gearhead]

It’s funny, but the flasher circuits and how they relate to the turn signals and brake lights is one of the things I understand the least!

It’s because this circuit and carburetors are controlled by the same magic. There are no absolutes. I think Bronco lean is influenced a little by the same magic.


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[DC_Gearhead]

I took all the bulbs out and turned on the flasher. It did the same thing. Flashed after turning it off. I switched flashers with my turn signal flasher and there was no difference.

I would say it’s the hazard switch but it only does it when the ignition is on.

Any more ideas on the hazard flasher issue?


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[DirtDonk]

Since the hazards have power all the time, normally, it would be unusual for there to be a difference with the ignition switch on. That might be a good clue for someone with better detective skills than I. Maybe the typical bad ground?

 

[ssray]

I have not dissected a turn signal switch, or the flasher switch for that matter and don’t know if they are physically put together like the diagram or not but anyway…… the turn signal switch basically operates like two double throw switches. The fixed pole connections from those switches go to the left and right brake lamps. With the turn signal in the neutral position those two poles are connected to the lead from the brake switch and a connection to the emergency flasher switch (more on that later). So the brake switch supplies power to both rear lights when you brake. When you turn the right turn signal that connection is broken and there are two other contacts that make a connection simultaneously. One of the contacts is connected to the turn signal flasher which gets power through fuse F5, which is 14 A. The other is connected to the front turn signal lamp. So both front and rear right turn lamps operate via the flasher. Same scenario with the left turn.

The emergency flasher switch shows as a four connection switch where all contacts are connected when the switch is operated. One has power from the emergency flasher through fuse F4 which is 20 A. One connection is the one mentioned that goes to the turn signal switch along with the brake light feed. The other two go to the front left and right front turn lamps. Physically it could be a 3 pole single throw switch with fixed connections tied to the flasher and the pole contacts suppling the rear and left and right front turn lamps.

The only switched power into the circuits is the two connections to the turn signal left and right switches from the turn signal flasher and the brake light switch if it is switched. I’d have to look further to check on that.

Have you checked to see what lamps are flashing when it hangs up and won’t shut off. If one of those connections from the turn signal flasher in the turn signal switch was tweaked and still touching the main pole with the turn signals off the brake lights or maybe a single rear light could be flashing through the turn signal flasher with the hazards off. Doesn’t make sense that the hazards would start it off though.

Nope, brake lights are hot through a fuse so kinda rules that out.

 

[DC_Gearhead]

I have not dissected a turn signal switch, or the flasher switch for that matter and don’t know if they are physically put together like the diagram or not but anyway…… the turn signal switch basically operates like two double throw switches. The fixed pole connections from those switches go to the left and right brake lamps. With the turn signal in the neutral position those two poles are connected to the lead from the brake switch and a connection to the emergency flasher switch (more on that later). So the brake switch supplies power to both rear lights when you brake. When you turn the right turn signal that connection is broken and there are two other contacts that make a connection simultaneously. One of the contacts is connected to the turn signal flasher which gets power through fuse F5, which is 14 A. The other is connected to the front turn signal lamp. So both front and rear right turn lamps operate via the flasher. Same scenario with the left turn.
The emergency flasher switch shows as a four connection switch where all contacts are connected when the switch is operated. One has power from the emergency flasher through fuse F4 which is 20 A. One connection is the one mentioned that goes to the turn signal switch along with the brake light feed. The other two go to the front left and right front turn lamps. Physically it could be a 3 pole single throw switch with fixed connections tied to the flasher and the pole contacts suppling the rear and left and right front turn lamps.
The only switched power into the circuits is the two connections from the turn signal flasher and the brake light switch if it is switched. I’d have to look further to check on that.

This logic really helps. Thank you!

I have question for you. The flashers I’m using are super sensitive for LEDs and say they “don’t need a load” to flash. When I was checking all the light buckets for possible feedback I noticed some millivolts on a couple of connections. Not much, but what are the chances those millivolts are what are keeping the flasher clicking after I turn it off? Probably not enough to start the flasher but maybe enough to keep it going? The flasher clicks slower than normal after I turn it off. Barely hanging on, like it’s going to stop any second.


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[DC_Gearhead]

Ok parking lights are fixed now. Pulled the switch, cleaned up the terminals, added some dielectric grease to the connectors and now they work.

Unfortunately this had no impact on the hazard flasher problem.


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[ssray]

This logic really helps. Thank you!

I have question for you. The flashers I’m using are super sensitive for LEDs and say they “don’t need a load” to flash. When I was checking all the light buckets for possible feedback I noticed some millivolts on a couple of connections. Not much, but what are the chances those millivolts are what are keeping the flasher clicking after I turn it off? Probably not enough to start the flasher but maybe enough to keep it going? The flasher clicks slower than normal after I turn it off. Barely hanging on, like it’s going to stop any second.


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You might have a good point there, maybe ,just possibly. Standard flashers of old had a bimetallic switch in them that would heat up from the current that incandescent lamps drew. It would bend and open the circuit and then cool and close again and so on. I‘ve thought LED flashers likely use an IC to generate the timing cycle. You could then use mixed lamps and the load would not throw the timing off. Never have found a circuit diagram for one though. In a two wire flasher It still needs to sense a load to start the cycle. Maybe some oxidation and corrosion (high impedance connection) somewhere causing the flasher to continue. Still tied to your switched power somehow for it to quit when the switch is turned off. Very puzzling though!

 

[DC_Gearhead]

I can’t find any real specs or cut sheets for these new circuit type flashers. So the one I had was a two prong but had a ground wire coming off of it. I just Amazon Primed one without the ground wire. From what I read, it’s not as sensitive and does require a load. But it is made for all LED or mixed setups. I’ll report back when I plug it in. It comes tomorrow. $10 so not too bad if it doesn’t make a difference


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[Brush Hog]

Had same problem with led flasher with ground wire. Swapped it out for one without and cleaned up dash to body ground and problem solved. But be warned I had 2 of those flashers that were bad right out of the box. As for fuel gauge I have had 2 issues that caused gauge not to work. #1 old sending unit float was filled with fuel so it wouldn’t float. #2 installed new sender with arm upside down so it always read empty.

 

[sanndmann3]

looks like another member of the upside down club... lol

Upside down club

If we can't laugh at ourselves. Became a member of the dubious upside down club. Put the motor, tranny and T case in as an assembled unit. Thought I would save time and install the cross member perches ahead of time. Got it all in and the T case looked low and engine was tilted down. Took me a...

classicbroncos.com

 

[DC_Gearhead]

Had same problem with led flasher with ground wire. Swapped it out for one without and cleaned up dash to body ground and problem solved. But be warned I had 2 of those flashers that were bad right out of the box. As for fuel gauge I have had 2 issues that caused gauge not to work. #1 old sending unit float was filled with fuel so it wouldn’t float. #2 installed new sender with arm upside down so it always read empty.

Thanks for sharing. The grounded one works fine for my turn signals. Did you replace both with the groundless flashers?

I wish mine were upside down. I think it’s just stuck with muck. My carb had a bunch of junk they came from the tank actually. I had to rebuild it and replace the filter. 3 years of sitting let the gas breakdown I guess. I’ll pop it off and look. Since I know the signal is good it must be mucked up….or upside down with a full float. We’ll see.


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[Brush Hog]

Thanks for sharing. The grounded one works fine for my turn signals. Did you replace both with the groundless flashers?

I wish mine were upside down. I think it’s just stuck with muck. My carb had a bunch of junk they came from the tank actually. I had to rebuild it and replace the filter. 3 years of sitting let the gas breakdown I guess. I’ll pop it off and look. Since I know the signal is good it must be mucked up….or upside down with a full float. We’ll see.


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Yes replaced both flashers with non ground wire flashers. With LED lights the flashers are pole specific too so I had to by an adapter piece to plug into the harness to flip polarity of flasher.

 

[DC_Gearhead]

I took the easy way out on the hazard lights. I put back in the incandescent brake lights and put in the regular “mixed” flasher with no ground. Adding the incandescent lights gives the flasher enough feedback to work properly.

For the record and any future readers, with all LED lights, I tried CEC’s incandescent electronic flasher EF32 and it came on but did not flash. I tried the EF32RL with ground wire which flashed but wouldn’t stop clicking after I shut off the hazards, and I tried the EF32SS which is for LED or mixed light types but it acted just like the incandescent flasher. It lit up but didn’t flash.

Since the load feedback is the issue, I decided to just put back in a couple of incandescent bulbs and try the EF32SS. It worked perfectly.

I am going to try and rig a couple of wires to reverse polarity like Brush Hog mentioned with all LEDs again just because I’m curious.


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