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Front Parking Lights Dead, 90 Bronco

7576 Views 17 Replies 4 Participants Last post by  miesk5
Recently picked up this Bronco, and I just noticed the front parking lights don't turn on? The turn signal works on both sides just fine, but the parking lights are dead on the front only???

Before I started probing around, I was curious if there is a common failure part that causes this?
(Also the power door locks and rear window switch don't work, but I assume those are unrelated circuits?)
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Swing, and a miss! ...
one strike but you still have some balls left!:thumbup

Think the park lts are fed by Brown wire & Black as da Grnd; the directional portion should be White/Blue
Have a meter or test light to see if you have 12V there?
The HD switch is a likely problem because of this;
Switch Fires, Part Number SW-2103: "...Over the past two years, this office has experienced fires caused by another potential problem in Ford vehicles. The problem exists within the dimmer portion of the headlight switch in Ford vehicles. The light switch involved is a Model SW-2103. These are the pull out type headlight switches usually located in the lower left corner of the front dash of Ford vehicles. The headlight portion of the switch has two pullout positions, the first for parking lights only, and fully out for headlights and parking lights. The shaft of this pull-out light switch can be turned clockwise and counterclockwise which activates a dimmer switch, lowering and raising the intensity of the lighting in the instrument panels respectively. Fully rotating the shaft counterclockwise past a notch activates the interior lights within the vehicles. The potential problem exists within the dimmer portion of this switch. The dimmer mechanism consists of a metallic resistive coil set inside a ceramic disc positioned over the shaft of the switch. The coil is exposed on its front side away from the passenger compartment. The front side of the coil passes across a contact permitting a current to flow through a certain portion of the coil when the switch is pulled our in its first or second positions. The greater amount of coil through which the current is permitted to pass (clockwise most position) creates the greatest resistance and therefore dims the dash lighting to its lowest intensity. The opposite position provides greatest intensity. Through our investigations, we have found that the coil can fail owing to wear and/or possible material defects or damage. A fractured coil can maneuver itself free of the ceramic disc permitting it to come in contact with the metal bracket which mounts and grounds the switch to the vehicle. When this occurs, a current can flow through a portion of the coil creating high temperatures melting the metal material of the coil and possibly igniting surrounding combustibles. This mechanism has been observed in three separate incidents by this office. Two of these resulted in a fire. The mechanism is precipitated by wear and/or defect in the coil mechanism. If the former is true, we expect there will be an increase in fires caused through this mechanism given an increase in service time. To this date the problem appears to be somewhat limited. However, this particular light switch has been utilized in numerous Ford vehicles. Therefore, a small increase in failure rate owing to age and wear could result in a significant increase in fire losses. The SW-2103 Light Switch Assembly discussed above is reportedly installed in the following Ford vehicles: 1986 -1997 F100, F150, F300; 1990-1994 Explorer; 1987-1994 Ranger; 1987-1990 Bronco II; 1992-1997 Aerostar..." Miesk5 NOTE: No Bronco Listed, but this may be the result of typos or incomplete research by the company.
Source: by

Diff fuses for power door locks and rear window

Diagram in a 90
Source: by ElKabong (Ken, El Kabong) at


for power door locks ; see some TS and wiring Links (87-89 should be same for your 90) in,my Site @
same for Tail Gate window Motor; my site @

Steve83's Info, wiring diagrams and da mac daddy..
Repair Synopsis; "...Be aware that: The tailgate latch switch on the driver's side seems to be a common problem, check it early. It keeps the window from being moved when the tailgate is open, & if not latched right, it'll keep the window from working at all. Try pushing the driver's side of the tailgate in while holding the button or key switch in the up or down position. If that makes it work, check out Steve83's How to align a Bronco Tailgate linked below. Ground for the motor connects up front, & at rest runs from there through both switches & both wires to the motor. When either switch is operated, 1 side's ground is disconnected & replaced by hot at that switch. Ground for the motor is not connected to it's case, but supplied through the wires. There are 2 seperate power sources & 2 fuses/circuit breakers for positive. 1 for each switch. The same 2 wires are used throughout for both up & down (Polarity is reversed by the switches). When the tailgate is open, you have to close the driver's side latch for the window to operate. Remember to open it before closing the tailgate. Testing: Does it make any noise at all? Like the motor's turning, but the window doesn't move? If so, there are torque pins in the motor's drive gear that commonly break & aren't too bad to replace. See the torque pin, Steve83's & Adrianspeeder's ... links. If it makes no noise, then it's probably in the electrical system. Fireguy50's wiring diagram is linked.... To test the electrical system, remove the access panel from inside the tailgate. Run test wires from the battery directly to the window motor connector (Yellow & red wires coming right out of the motor) to confirm that the motor works. To lower the window, it should be positive to red, & negative to yellow. Be ready for the window to move, keep hands & wires clear. Make all the connections but 1, then connect & disconnect the last wire quickly to see if it tries to go the right way. If it tries to go the wrong way, reverse the wires (This also makes it so that you can lower the window & get the tailgate open to continue testing). A- If it runs & the window moves when wired directly to the battery, perform the following tests: A.1- With both switches at rest & the latch switch closed, connect a tester between the positive test wire from the battery & each wire from the tailgate loom at the connector for the motor. Both should read 12v. If they do the ground is good. If they don't, refer to Fireguy50's wiring diagram linked above to trace it down, or tell us what you find. A.2- With the latch switch closed, connect the tester between the negative test wire from the battery & each wire from the loom at the connector for the motor. The red wire should read 12v when either switch is in the down position, the yellow wire should read 12v when either switch is in the up position. If they don't, refer to Fireguy50's wiring diagram linked above to trace it down, or tell us what you find. A.3- If everything tests ok, but it still doesn't run, there's a couple more possible causes to check: -Sometimes the connector for the tailgate motor will test ok, but not make contact when plugged in. You might try backprobing the motor side wires with the plug connected. On mine I removed it & soldered the connections. -It's possible for a damaged wire to carry enough load to show 12v on a tester, but not enough to operate the motor. Look for worn areas, especially in the loom between the body & the tailgate. B- If it runs but doesn't move when wired directly to the battery, in addition to your electrical problem, the torque pins in the drive gear are probably broken too. Run the electrical tests in section "A" above, & see the torque pin, Steve83's Tailgate Tech, & Adrianspeeder's links above for the torque pin replacement. C- If it doesn't run at all when wired directly to the battery, it sounds like it's time for a new motor. See Steve83's ... & use the info for removing & replacing the motor. On my truck there were multiple bad connections, so it was hard to isolate the problem. Someone before me used a ton of crimp connectors . Basically I ended up removing them & soldering all the connections, & eliminating the corroded plug to the motor..."
Source: by ElKabong (Ken, El Kabong) at FSB
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Thanks for the reply, although regarding the possible defective headlight switch, I didn't see any relation to having just dead front parking lights? Oh well, I still have to get into it and start poking around with test equipment.

This damn Bronco has had more wiring BS issues than any Ford I've ever owned from this era (87-96)? Luckily I have the understanding of electrical circuits enough to track down the problems, I just lack the patience of twisting myself into a pretsel to peer under the dash at the nest of wires and switches. :toothless
yeah the HD fire issue doesn't specifically address the park lts. but they get so hot contacts and such go South.

I'd try the voltage tests at the light connectors first. That way you can isnpect the conns/wiring for corrosion etc.
Turn, Tail, Brake, Head Light, Hazard, Ignition Wiring Diagram for 84 Bronco & F-Series; "...Similar to 80-91 Bronco & F-Series..."
Source: by Steve83 (Steve, That dirty old truck) at

btw, I thought that I had mentioned this. but now i see I didn't; my 96 won't get the parking lt to work in the PL detent position; I had the SW out 2 yrs ago to ck the PSOM.
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OK. lets keep this simple.

Did you check the bulbs it is possible they are out if not check and replace with correct ones

Next the bulb socket check to se if you are getting power if you are good

check the wires looking for splices some smart people will wire things in the stupidest location

Next headlight switch it is possible that there is a bad connection or terminal pull that and look
Yo yo ... Well I think both of you may be right.

I went into the garage today and it was tricky just to even get the Parking Lights to come on in the rear. I had to fiddle with the Headlight Switch to get the perfect position where they would come on. So I think the contacts are junk in it, like said above.

When the Parking Lights did come on, I checked the driver's side front parking light Socket and the Brown wire (from Headlight Switch) had 12V: Good. The Green/White (from Turn Signal Switch) was at 0V: Good. It was also fluctuating voltage when actuated, so that is good. The Black (ground) was good at -12V when checked against positive battery post. So it seems all terminals in the Socket are receiving the proper voltage.

But, when the bulb is placed in the socket, it doesn't illuminate. Now everything I know about circuits tells me that if the power wire is transimitting 12V and the ground circuit is good, the bulb should illuminate, period. It doesn't, so I think I'm dealing with a bad Headlight Switch and two dead bulbs. That is the best guess I have without pulling the passenger side and checking it ... which I'll do ... but I definitely need a Headlight Switch.

Thanks for the help. :beer
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Good job on TS ing it!
and ty for confirming colors.
Update For Archive Searches ...

Okay! So it wasn't a bad Headlight Switch after all ... it was a bad fuse. Fuse #4.

Apparently a common symptom when fuse #4 pops is you can still turn on the parking lights, but you have to get the knob pulled just right ... Obviously that is incorrect; replace #4 fuse and problem is solved ... What seemed like it was defective contacts in the headlight switch, was just a blown fuse as illustrated below. :banghead :toothless

Although, both parking lights up front were rightly cooked. The main filaments for the parking lights (3157 bulbs) were vapor; Hence on and so forth blah blah, the reason the blinkers still worked, but not the parking lights in unison with the tails. The Previous Owner was an idiot with electrical, it seems? :argue

Now off to tackle the dead door locks and rear window switch ... he neglected ....

(My Chilton and Haynes repair manuals lack the wiring schematic for some of these wires... Why??????)
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Why did it pop the fuse though? That is the issue you need to resolve. Hyanes and Chilton are for the backyard mechanic, you need a Specific service shop manual for the best info.
and thanks for posting the pics and colors.

* and as dabranco wrote... lets keep this simple...LOL

big help... esp when a prev owners has messed-up da wiring!
Keeping it simple. Check or replace the necessary fuses, then check grounds. If these 2 steps are not the case, then you need to dig deeper and start running down wires and testing them(this requires an oHMmeter). That is the KISS method I choose to follow.
Hyanes and Chilton are for the backyard mechanic
Well, I ain't gots me no certified Ford tech in me garage to supply the proper manuals, so I take my 'backyard mechanic' butt up to the local parts house and buy whats they gots.

Yeah, those manuals are surely lacking for we high-brow chaps; But they usually provide enough info to get a repair job done for somebody with a slight inclination for what he is doing ... Which I clearly do not. :toothless:

I don't know why the fuse blew? I have NO CLUE what all went on with this Bronco in it's past, but the PO obviously didn't fix some things before pawning it off on the used market while he went out and bought a Prius or something of the same flavor. I'm guessing he burned out the main filaments in the parking lights by fiddling with the switch all the time, unable to track down the issue? Or maybe the fuse was running close to capacity and was old?? I don't know, but after replacing it, all wires were conducting at system voltage, with minimal resistance. I drove it around for about 15 minutes last night after figuring it out, just to see if it would pop. It did not, and I assume that is sufficient time to heat up the fuse ... If not I'll be back soon with more drama ... or a new Raptor!
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Hey now lol. I never said ******* mechanic! Yeah I too have the AutoZone books, but they lack soo much good info we amateurs could benefit from. On the other hand, not having the extra info makes us really good guessers hehe. Glad its fixed bro!! Sometimes old wiring if placed in the ideal conditions will corrode inside the plastic sleeve and act as a big resistor instead of a conductor and just make weird stuff happen. GM headlight wiring have a similar issue in mid 90's.
Yeah, books suck! I climbed under the bumper to see which wires the PO 'pinched' for trailer lights on a second socket he installed (as opposed to just buying an adap-tor?), and the books lack any schematic for that wiring back there as well.

I guess people are just supposed to guess what the engineers intending with the different color wires ... like Deal or No Deal ... "Wonder what's in case #9?? Oh crap, the million dollars, schucks!"

Or perhaps for the $20 buy in price those Chilton folks expect us to unravel all the loom and tape to discover, "AhhhhhHH, the Purple/Pink wire goes all the way back to the gas tank ... Now just have to wrap up the twenty feet of harness and drop that gas tank to see which component it goes into, the sender or the pump!!??"

I don't think I have any corrosion issues, because at those headlight switch terminals, the current is flowing through them sooo close to battery strength (alternator when running) that it is fine from my experience ....... Famous last words before the dreaded freeway fire an hour from home. :haha
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Ford had a bad habit of changing some wire colors from year-to-year for some resaon; could have been a different harness supplier...

Someday, suggest you buy a "genuine (not chilton EVTM or some off-brand) 1990 Ford Bronco Electrical and Vacuum Troubleshooting Manual via e bay or someone here.
one ex is;
1990 FORD F150-F350 TRUCK Electrical Vacuum Manual Book
by Ford Motor Company 29.64
Product Features
New Original
Light Duty Trucks, Bronco
approx 150 pages
Electrical/Troubleshooting Only
Published by the factory to provide information on diagnosis, service procedures, adjustments & specs, there is none better. Loaded with diagrams & illustrations to help disassemble, repair & reassemble various components.
2 pounds

What else is on that Fuse? Instrument Panel Lighting?
Did they go out too when fuse was blown?

I use a a low resistance test light to find the shorts;
like this by Chris B at

excerpt; "...The other way I use a test light is to check for short circuits. This test is done by putting the test light in place of the fuse. I use the small Radio Shack jumpers to do this. If you turn off all of the lights or loads on the circuit being tested, the light will go out when you have found the short, but it will light brightly while the short is still there...."
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Ah, now you're talkin'! I'm gonna pick one up right now ....... Although with the current Congress, perhaps I could petition them to create legislation that says, 'All Ford truck owners are entitled to one' ... Then I get it for "free"! ;)

What else is on that Fuse? Instrument Panel Lighting? Did they go out too when fuse was blown?
Well, it is bright inside my garage, but I took the time to create a dark pocket with my hands together and pressed up against the instrument cluster. And then I leaned in slowly and peered into my dark palms. There was no illumination from the dash lights, so the lights were out too .... Unless the light saw my big eye sneaking up and so it snuck out first? Doubt it? ....

excerpt; "...The other way I use a test light is to check for short circuits. This test is done by putting the test light in place of the fuse. I use the small Radio Shack jumpers to do this. If you turn off all of the lights or loads on the circuit being tested, the light will go out when you have found the short, but it will light brightly while the short is still there...."
Ahhhh, now this is a good idea. I actually saw a guy doing this once, but didn't retain it in my grey matter for some reason?> I guess I reserved that space for more important things in life like naked women>? :twak
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i try not to think 'bout naked women much... just oil, grease, lube, ahhh naked women....oil, grease, lube
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