Question for the electrical wizards here!

[aja8888]

Question for you electrical guys.

On my 1998 Ford F150, I have signal lights embedded in my outside mirrors that flash with the normal turn signal stalk activation. The mirror flash is made up of LEDs (remember, truck is 21 years old) and form a pattern like this: “<” (in each mirror.

These have stopped working, although I see a faint reddish glow in the mirror where the LED string is when the signal is engaged. So I took off one mirror plate and backing and found the LEDs are encapsulated within a hard rubberish backing that covers the back of the mirror. Two power leads are sticking out of the backing material and connect to a 12V source inside the mirror housing.

When I tested the power to the mirror (output connector) LEDs when cycling the signal light on the side I was testing, my digital voltmeter reads ~10.7 volts (cycling between 0 and 10.7 quickly).

Three questions:

1. Can I accurately check a DC voltage with a VOM when it’s quickly cycling on and off?

2. Can these LEDs fire effectively at a voltage less than 12 VDC?

3. Is it possible the LEDs are “dying” after 21 years and only work at partial brightness?

Note: the mirror glass is OK, but on close examination, a "scalloped" looking defect is visible within the thickness of the glass. Nothing is cracked or broken, but you have to look close to see the scallop lines within the glass.

Thanks for any help or suggestions.

P.S. OEM replacment mirrors are not readily available and if there were, they would cost quite a bit, I am sure. Plus, I'm not sure it's a mirror problem.

Pic of scalloped mirrors:



Back of mirror:

 

[Mr._Graybeard]

A lot of wonky signal lights are the result of a weak ground. I'd look first for the point where the circuit grounds to the chassis and make sure that connection is clean.

 

[aja8888]

A lot of wonky signal lights are the result of a weak ground. I'd look first for the point where the circuit grounds to the chassis and make sure that connection is clean.

Tracing those wires (signal harness) brought me to the steering column and clockspring area, Grounds are very clean and no corrosion seen in any of a half dozen connectors. Good idea, though. Battery voltage is 12. - 12.6 volts everywhere I checked it. That includes at light housings in the fenders.

The truck has 46,000 garage-kept miles on it and no corrosion noted anywhere.

 

[Jerry1]

Hook the LED’s directly to the battery (12v source) and see if the lights work. If so, the low reading of voltage may be the problem. Either way, you rule out or rule in the LED’s.

Do both sides do exactly the same thing? It would be unusual for the LED’s on both sides to go bad at exactly the same time.

 

[gauss]

So the LEDs in both mirrors (driver and passenger side) have both gone dim?

Have you checked your system voltage at the battery when the vehicle is running.

It should be ~13.x-14.x volts.

If this tests out fine, I would next try to "bench test" the mirror.

You would need to know the polarity of the wires, and a scheme to connect a power supply to the mirror directly.

Do you have access to any service documentation (OEM or third party) for the vehicle? They typically contain wiring diagrams/schematics that would help significantly.

-gauss

oops: Looks like Jerry1 beat me to the punch.

 

[aja8888]

Hook the LED’s directly to the battery (12v source) and see if the lights work. If so, the low reading of voltage may be the problem. Either way, you rule out or rule in the LED’s.

Do both sides do exactly the same thing? It would be unusual for the LED’s on both sides to go bad at exactly the same time.

Couple of things I forgot to mention. I have owned the truck for less than a year, so I have no idea when the mirror lights went south as they did not work when I ought the truck.

I did wire one mirror up to the battery directly and the LEDs glowed, but it took a few seconds to get to full (I think) brilliance. My gut feeling is twofold:

I am not sure if measuring the cable to the lights can be done accurately with a volt meter because of the quick cycling on the flasher (my 10.7 V measurment).

Secondly, 21 year old LEDs may be defective and not respond to cycling voltage as when they were new. I don't know enough about LEDs to understand their lifespan and properties.

 

[aja8888]

So the LEDs in both mirrors (driver and passenger side) have both gone dim?

Have you checked your system voltage at the battery when the vehicle is running.

It should be ~13.x-14.x volts.

Done - 14.2 V charging, newer battery.

If this tests out fine, I would next try to "bench test" the mirror.

See above.

You would need to know the polarity of the wires, and a scheme to connect a power supply to the mirror directly.

Wire are color coded, black being ground.

Do you have access to any service documentation (OEM or third party) for the vehicle? They typically contain wiring diagrams/schematics that would help significantly.

No.

-gauss

oops: Looks like Jerry1 beat me to the punch.

See answers above.

 

[txtig]

P.S. OEM replacment mirrors are not readily available and if there were, they would cost quite a bit, I am sure. Plus, I'm not sure it's a mirror problem.
]

My son and I replaced one of the side mirrors on his 2006 F150. It was an after market (non-OEM) mirror from Amazon. About $70 if I recall correctly. Had to remove the interior door panel to swap it out.

 

[Jerry1]

Just guessing here, but if the LED’s took awhile to get to full brightness, then they are bad. I think they have other electronics involved (resistors) so maybe they are old. Also, I think LED’s have improved over the years so maybe they’re not working as they did when original.

Have you looked to see if you can buy replacement LED’s, or is it a sealed component of the mirror?

 

[JoeWras]

Just guessing...

Sounds like there may be a capacitor in that circuit. Perhaps buried in the module. I say this because you mention the "few seconds to reach brilliance."

Capacitors are a known weak spot in many circuits. Especially I would think one exposed to temps of -20C to 60C.

Edit: Jerry seems to be ahead of us. Maybe we are behind an R/C circuit too? Resistors too...

 

[aja8888]

My son and I replaced one of the side mirrors on his 2006 F150. It was an after market (non-OEM) mirror from Amazon. About $70 if I recall correctly. Had to remove the interior door panel to swap it out.

I'd really like to replace these stock mirrors since the motors and gearing are worn and positioning the glass is not done easily (mostly by hand). The ones I looked at are about $220 (excellent quality - not knock off Chinese crap) but I wanted to make sure the 10.7 volts measured by me (cycling) is for real vs. 12 volts that may be there because I don't get an accurate reading with a digital Voltmeter, if that's the case.

So my question revolves around the measurement and if it is accurate or not accurate. I don't have any better way to test the voltage and need to be accurate on this if I am going to order new mirrors with signal lights in them.

I have no confidence in the LEDs in the old mirrors. I didn't even know LEDs were mainstream back in 1998.

 

[aja8888]

Just guessing here, but if the LED’s took awhile to get to full brightness, then they are bad. I think they have other electronics involved (resistors) so maybe they are old. Also, I think LED’s have improved over the years so maybe they’re not working as they did when original.

Have you looked to see if you can buy replacement LED’s, or is it a sealed component of the mirror?

I'd have to Dremel the back of the mirror cover open to look. That had crossed my mind and I may just do that just to see what 21 year old LEDs look like.

 

[bjorn2bwild]

Have you tried hooking up another 12v led light array (turn signal, brake) to the source going to the mirror?

 

[aja8888]

Have you tried hooking up another 12v led light array (turn signal, brake) to the source going to the mirror?

There are no other LED arrays on the truck.

I don't have any LEDs laying around and no other ones are on the truck. I suppose I could go buy a 12 V LED bulb (or array?) at Autozone to test that. Good idea!

The other signal lights work off the same Multi-function switch buried in the steering column. But all the other lights (halogen bulbs) are working. To hook those wires to a test bulb is probably a good idea, and I will have to make one up to do that (tonight).

 

[aja8888]

Aha!

I found an automotive LED in my shop and will solder two leads on this and use it as a test on the mirror wiring.

 

[ERD50]

... So my question revolves around the measurement and if it is accurate or not accurate. I don't have any better way to test the voltage and need to be accurate on this if I am going to order new mirrors with signal lights in them. ....

Probably not. Digital meters take some time to settle. You can get a sense of this by connecting it to the car battery, and noting how long it takes to get to a stable 12.8 V or whatever. You could even touch and release one lead alternately (one-one-thousand; two-one-thousand, etc), pretending you are a turn signal (have DW post a video to youtube!), to get a sense of it.

Another unknown - I would not have hooked the leads directly to 12V car battery w/o knowing that was how they operate. It is possible (though I think somewhat unlikely), that the power they are fed is not just switched car battery voltage. It may be current limited, or 'processed' in some way. There may be a circuit internal to the mirrors/LEDS, no way to know for sure.

If they really took time to come to full brightness, that would not be a simple R/C circuit, it would take HUGE capacitors to delay the brightness for seconds, they just would not do that. There might be a high frequency switching circuit in there that is flaky. Or just a flaky connection in a simple LED-resistor string.

Both at the same time? Hmmm, that sounds more like the control circuit, which would be common. How about emergency lights - any different?

I have no confidence in the LEDs in the old mirrors. I didn't even know LEDs were mainstream back in 1998

I'm curious about this as well. We take things like this for granted now, but wide spread use is fairly recent I think.


-ERD50

 

[aja8888]

Both at the same time? Hmmm, that sounds more like the control circuit, which would be common. How about emergency lights - any different


I'm curious about this as well. We take things like this for granted now, but wide spread use is fairly recent I think.


-ERD50

I never implied both mirror signals went out at the same time. I thought I said they were both inoperative when I bought the truck a year a go.

If you notice mirror signals in newer cars, they blink and recover very quickly.

I believe I will dremel open the back of one mirror and see what's in there since I will be buying new mirrors. In the meantime, I will solder leads to the LED bulb I came across in my shop and see how that responds to the mirror lead.

 

[JoeWras]

If they really took time to come to full brightness, that would not be a simple R/C circuit, it would take HUGE capacitors to delay the brightness for seconds, they just would not do that. There might be a high frequency switching circuit in there that is flaky. Or just a flaky connection in a simple LED-resistor string.

Or maybe he burned it out. Probably not. Just kind of joking. I think.

I'm curious about this as well. We take things like this for granted now, but wide spread use is fairly recent I think.

From that era, I remember some limited automotive LED applications. Brake lights on the Caddy. Remember those? They disturbingly were on-off with no rise or decay. It just seemed, well, weird. Anyway, LEDs in cars have been around a while. It wouldn't surprise me to see this small application use them.

From Wikipedia:

https://en.wikipedia.org/wiki/Automotive_lighting

In 1993, the first LED tail lamps were installed on mass-production automobiles. <Joe: doesn't say where>
...
LEDs were first applied to automotive lighting in centre high-mount stop lamps (CHMSL), beginning with the 1984 Chevrolet Corvette. Adoption of LEDs for other signal functions on passenger cars is gradually increasing with demand for the technology and related styling updates. In North America, the 2000 Cadillac Deville was the first passenger car with LED taillights.[111]

 

[ERD50]

I never implied both mirror signals went out at the same time. I thought I said they were both inoperative when I bought the truck a year a go.

If you notice mirror signals in newer cars, they blink and recover very quickly.
...

Oh, I see that in a later post - your OP just said they "These have stopped working, ", which I read as a sudden thing.

Or maybe he burned it out. Probably not. Just kind of joking. I think. ...

Right. As I said, there is a chance that they don't run directly on switched battery voltage, and could be burnt out by applying it.

I've done it myself a few times, thinking "I'll just jumper this to get it working for now", and "zapp!" - oops, the connection wasn't straight voltage, it had a current limit in it. It happens. And it might be convenient for them to include that current limit in the control module, since they already have electronics in there, rather than distribute that out to the mirrors.

W/o a schematic, or specific experience, no telling.

-ERD50

 

[aja8888]

Guys, I have no wiring diagrams for this truck and even if I did, these OEM mirrors were the "first year" and not all F 150's got them since they were an option. This truck is highly optioned. In later years, Ford went with a different light in the mirrors as an option. The wiring diagrams can be bought, but I didn't want to go through that process.

The folks on the F 150 Forums are clueless as I have posted there too. Of course, everyone there has new trucks these days!

 

[aja8888]

My plan going forward is to:

1. Set up a test LED for the power at the mirror.

2. Buy a pair of aftermarket mirrors. These guys:

https://www.amazon.com/dp/B0779G4LR...olid=222GWTUDE1ERH&psc=0&ref_=lv_ov_lig_dp_it

(they are much better units and have blind spot sub mirrors. Plus the gearing should work better than mine.)

3, Cut off the back side of the old mirror to see what's in there for educational purposes. '

I'll post photos.

 

[eytonxav]

Although this individual had more turn signals out besides the one in the mirror, some of the info here might provides some clues:
https://www.fordf150.net/forums/viewtopic.php?t=59341

 

[kgtest]

Tracing those wires (signal harness) brought me to the steering column and clockspring area, Grounds are very clean and no corrosion seen in any of a half dozen connectors. Good idea, though. Battery voltage is 12. - 12.6 volts everywhere I checked it. That includes at light housings in the fenders.

The truck has 46,000 garage-kept miles on it and no corrosion noted anywhere.


View attachment 28986

That has got to be one of the cleanest lowest mileage trucks of its day. Nice work keeping it clean man! I would be surprised if any bulb lasts 20years to be honest. That's why I use the blinker sparingly, especially with the price of blinker fluid these days.

 

[aja8888]

That has got to be one of the cleanest lowest mileage trucks of its day. Nice work keeping it clean man! I would be surprised if any bulb lasts 20years to be honest. That's why I use the blinker sparingly, especially with the price of blinker fluid these days.

Thanks, 88 year old guy had it and I bought it out of the estate from his nephew. Even the leather seats are mint. Has all new brakes and tires. Came with the fiberglass bed cover and inside the bed it has a bed liner.

 

[aja8888]

Although this individual had more turn signals out besides the one in the mirror, some of the info here might provides some clues:
https://www.fordf150.net/forums/viewtopic.php?t=59341

Thanks, I'll go through that tonight.