Mechanic: Choose Your Own Adventure · 11:46pm May 30th, 2019
Okay, kids, got a special one for y’all today! It’s gonna be a choose-your-own adventure style blog post, where you get to diagnose the vehicle along with the mechanic! Won’t that be fun?
So without any further ado, let’s dive in!
We’ll begin by describing the parts of the electrical system on this Explorer that you need to know. Simplified, ‘cause I don’t feel like diagramming the whole thing. Also, I’m working from memory and logic, so I can’t say with 100% certainty that the rear lighting system is wired exactly this way, but for our diagnostic purposes, it is.
First, the givens. All circuits I’m about to describe below are power-side controlled (i.e., the positive wire goes to the switch), and all of them ground (return) to the same chassis ground.
I’ll also give you a freebie: there are no broken or shorted wires.
1. The parking lights are individually fused, and controlled by the headlight switch.
2. There are three brake lights. All three are fused together, and they all go to the same brake switch.
2a. After the switch, the wires split; the high-mount LED brake light (CHMSTL) is controlled by one of these wires.
2b. The other wire goes to the multifunction switch first, because on this vehicle the other two brake lights are also used as turn signals. Then one wire goes down each side of the vehicle to the rear taillamp assemblies.
3. The reverse lights are controlled by a switch on the side of the transmission. That wire isn’t used for anything else.
4. Each of those circuits has its own supply fuse--which we’ll call 1, 2, and 3.
Everybody follow along so far?
I’ll also be putting a picture of a pony after each diagnostic section, just in case you want to figure out what might be wrong for yourself before reading ahead.
The customer’s complaint is that NONE of the brake lights work. He also says that he put all new bulbs in both tail lights, so he knows that those are good. The parking lights do work.
Can you determine from the description what component in the system is bad?
If you guessed either the fuse or the brake light switch, very good! Since we know that the circuit splits after the brake light switch (2a and 2b), there is no single failure that could take out all the circuits, and I told you above that the wiring to the switch was good.
Of course, if it was this easy, I wouldn’t be writing the blog post. The customer pulled the car into the shop, and my manager said that the brake lights WERE working, all three of them.
The customer swears up and down that they weren’t, not even after he replaced the bulbs. Assuming that the customer isn’t lying, what is the only component that could have failed to cause this?
If you guessed the brake light switch, congratulations! A fuse can either be blown or not blown, it can’t change back and forth from one to the other.
Well, now we’ve got a bit of a dilemma on our hands. It’s possible that whatever failed takes a bit of time to go wrong; maybe it’s got to get hot or hit a couple of bumps or whatever. So my manager tells the customer to drive around town a bit and see what happens. He hops back into the Explorerer and drives off. As he does, my manager looks out the door at the retreating plot backside of the vehicle and says that none of the brake lights are working now.
Thus confirming the diagnosis, right? A brake switch is a moving part, a spring-loaded plunger with little contacts in it, so it could very well work sometimes and not other times.
I go back to the car I’m working on. From what I’ve been told, there’s really only one thing it can be.
The customer brings the Explorererer back, I drive it into the shop, and the brake lights work. The reverse lights don’t.
Is there any failure that could explain the reverse lights not working and also the brake lights not working, but the parking lights are working?
If you guessed no, there is not a single failure that could cause all those symptoms, you are correct. We’ve got multiple failures. Of course, we don’t know that the reverse lights ever worked--the customer didn’t say either way. They’ve got new bulbs in them, according to the customer, but that doesn’t mean that they work.
So clearly the next thing to do is take the bulbs out of the tail light assemblies and see what they look like, see if there’s anything there which jumps out at us.
new bulbs my 
Well, that explains the lack of reverse lights, at least. Incidentally, the sockets were also bad. Nobody had them in stock, so I cleaned the old ones up as best as I could, and got one of the reverse lights to work reliably. The other one, not so much. Potentially, if he hits the right series of bumps in reverse, it might come on, I dunno.
But we’ve still got this pesky brake light problem to deal with.
I gotta impart a bit more information on y’all, which should help. I haven’t been entirely truthful . . . well, rather, my manager hasn’t been entirely truthful about the symptoms.
Just like the customer didn’t put in all new bulbs (the brake light bulbs were new), the CHMSTL was actually working even when the other brake lights weren’t. In fact, the CHMSTL always worked. But the other two, the left and right brake light, they didn’t always work, and when they didn’t work, they both failed simultaneously.
They also only failed when the customer was driving the vehicle.
Knowing that, let’s see what y’all think. Scroll up if you need to and re-read how the system works one more time, and then make your guess. If you have a question, one which I have not answered about what did or did not work, keep that question in your mind, becuase you might very well be on the right track here.
If you either decided that the only thing that could have failed was the multifunction switch, or you really want to know if the turn signals worked when the brake lights weren’t working, you’ve got the exact right mindset for this.
(You’re also probably wrong about what component had actually failed, but with the information I’ve given you thus far, it’s a very logical and sensible conclusion.)
A very few of you might have had a different question, one which doesn’t seem related at all to the issue but in fact is at the heart of it, so I’ve got to do a bit more scene-setting.
Both my manager and I are about the same size, over 6 feet (10 meters) tall. The owner of the vehicle was shorter, maybe 5 feet (less than 10 meters) tall, and also has a prosthetic leg.
[One of my readers just had his (or her) Eureka moment.]
I was able to make the brake lights--just the two on the side, not the CHMSTL--malfunction every time by changing the steering wheel from tilted all the way up to tilted all the way down.
Every single time.
You see, Ford thought it was a good idea to securely fasten the wires to the steering column so they didn’t snag on anything, and they were right, but they should have left just a little bit more slack in them. When the vehicle gets old, they like to pull out of the connector.
Also, sometimes people break the connector when they replace the multifunction (turn signal) switch.
Steering wheel tilted up, brake lights work. Tilted down, they don’t. And in hindsight, it’s quite obvious how a guy with limited leg mobility would tip the steering wheel up before getting out of the vehicle, and how my manager and I wouldn’t tip it back down before driving it. How when the customer got in to drive it, then he’d tilt it down, and then of course the brake lights wouldn’t work.
This is not the first Ford of that vintage I’ve fixed that has had the same exact problem. The last one, somebody was in the column, broke the lock tabs, and improvised.
This one, the tabs in the connector that hold the wires in place just gave up, and when I had the shroud off the column, I could watch as the wires pulled out when I tilted the wheel down, then pushed back into place as I tilted it up.
The repair was as easy as getting a new connector and re-pinning it, and then the guy and his Explorerererer went on their way.
Also, Super Trampoline is running a feghoot contest, if that’s something you’re interested in.
Sorry, I lost you after the freebie. Cute pics, though.
The faulty component is the Ford. Replace with a Jeep.
I'm dying XD
Umm... Just a little nit-pick here. Six feet isn't TEN metres. It is almost TWO metres, not ten. If you were ten metres tall, you'd be able to see over most single-story buildings. 1 metre is equivalent to 1.0936 yards, or 39.370 inches.
You were correct, the wires weren't broken, just not connected all the time!
5066993
Admiral was counting in binary.
My first thought was a problem was the manager.
Second was driver was a fatarse and needed to either move things or moved things when abusing the vehicle.
Sorry, just a bit fuzzy this time of night. Always try and give wires around movement points extra flex room to try and reduce work fracture fails.
Heh, well my question was the 'Do the turn signals work' one. Goes to show now much knowing what common issues stupid engineers install in various cars helps.
ok first i love my ford's /// well most of them. the ford exploder is and was one the biggest piles of garage death traps ford made.
of all the problems i am sure you know electrical is right in the top 3, i have worked on a few in my day and they remind me to much of the pinto or vega to put it simply disposable.
after it brakes crush it and make PBR cans out it it.
i have spent time it salvage yards and of all the explores i see about 70% are burnt from the engine bay or dash. yep just fire traps.
sorry AB for ranting but i watch a brand new one burn to the ground just sitting in the church parking lot one day, i can say they make a pretty fire.
I don't know if this has been point out but you would be only 2 meters tall because a yard stick is almost a meter and that is all I ever care to remember about the useless metric system.
wait was this about cars? Cause I keep getting distracted by ponies
Actually, my first thought was "So the bulbs have been replaced. Did they use the *right* bulbs?"
Yeah, my wife likes to 'fix' things on her car.
I saw "Explorer". First thought; "Ah, an exploder (you read that correctly) having problems. Typical."
Second thought? "It's probably a plug."
Last thought. "... that's every Ford with a tilt column. Heaven forbid it telescopes. No. Thank. You."
5067082
The wrong bulbs was my first thought. Then as Biscuit kept going, I started leaning towards a loose/bad connection.
5066976
Had a weird one a few weeks ago myself: was with a well-seasoned Deere mechanic working on an off-brand tractor. Circuits for the lights needed some attention, but the flashers were still out despite new bulbs (the right bulbs, mind you). Did some twisting of the mounting bracket, got the lights "working", but no blinking.
Now, normally the convention is that the flasher unit is housed in the sheet metal in front of the operator's station close to the instrument cluster. Not the case on this thing. We originally thought the unit was somehow built into the system somewhere.
Shouldn't have been surprised at this unorthodox design choice, yet we both were. 
The reality: the unit was housed in the rear worklight housing.
5067061
Considering that many automotive parts (and brands, in particular) are in the metric system... and that ten meters is taller than most houses (at approx. 32.8ft)... and that the measurements were an inexact "ten meters" and a very nonscientific "less than ten meters"...
I daresay it's an exaggeration.
And as an exaggeration, I do believe it gets the point across quite well. The Admiral and the manager are giants, the customer a dwarf.
... Be wary the dwarves of Khazad-dûm.
5067157
I guess that I don't see that difference the difference in higth as being that severe.
Came here for the pony pics, stayed for the pony pics (and Detective Admiral).
5066993
10m tall. I’m fairly sure he’s using the loading dock entrance at conventions...
5068059
If anypony here's an Anime fan, you might remember the series Patlabor. Those mechs were 8 metres tall on average. So if you want to get a comparison, check out the series and add another quarter of their height onto them. Then you'll get an idea just how tall ten metres is.
lol clearly you've never seen a cracked fuse.
Those are a bitch to diagnose.
Also, I think the moral of the story is:
Never believe a goddamn word the customer says.
5066984
That’s okay, it happens.
Thank you!
5066986
I have a Jeep! And interestingly enough, one of the tail lights doesn’t work on it, which I haven’t fixed because the tailgate doesn’t open, either.
i.imgur.com/5JptWpO.jpg
(hey, it was not only cheap, but I bought it from ROBCakeran53, the author of Amigo)
5066991
5066993
I know, and it’s a real problem. My house is only single story, and I bang my head on the ceiling all the time. Gotta kind of crouch down to go through doorways in the house. . . .
And work . . . the hoists don’t lift the cars all that far, either, so a lot of times I’ve gotta sort of crouch over working under them. It’s really inconvenient.
Now, I know you’re doubting my metric conversion, but I promise if you look through previous blog posts, I’ve always been ten meters tall.
At least it makes me easy to find at conventions.
5067011
Exactly!
I mean, it’s a fine point, but then I didn’t want to overcomplicate things in the blog post.
5067013
(I’ll use that next time somebody complains about my faulty conversion)
You weren’t entirely wrong; that was one of the problems.
Also not entirely wrong. There could be a whole subset of these things that involve what the customer does to their vehicle which we can’t duplicate because we know better.
This is something that all automakers should know, and yet they often fail at figuring it out. GM had a similar problem with their ABS wires in the front of W-body cars; it turns out they should have known that the front wheels pivot so the car can turn, but they apparently hadn’t accounted for that when they designed the wiring. And the wires in the door jamb are problematic on some vehicles, too.
5067024
Had I looked at a wiring diagram, I could have told you if they did or did not . . . I’d have to guess no, but I never checked that. As soon as I knew that tilting the column caused the issue, I didn’t go any further into what worked and what didn’t.
Just like a vehicle that’s the star of an upcoming blog post, I know two things that I fixed when I located the actual problem, and there were probably other failures that I didn’t know about but also fixed.
5067025
No question; a guy who drives one and who worked for Ford when they designed it told me that once.
Yeah, top three right behind rolling over because of a flat tire and rolling over just because they can. Although they are marginally more stable than Bronco IIs.... Not that Chevy’s baby Blazer was much better.
A noble way to repurpose one.
F-150s did that, too, with the faulty brake switch. And, for that matter, a whole slew of other blue oval products. My old Grand Marquis actually had an open recall for that switch, and I considered taking it to the dealer but just never bothered. Didn’t have the time, which was a shame; I would have loved to roll up in that hooptie and have them fix something for free on it.
5067061
It’s easier to round up to the nearest ten IMHO. Plus, ask anybody who’s seen me, they’ll tell you.
5068366
Yeah, Jeeps are a headache but damn they're hard to kill. Funny thing, I have a rear blinker not getting current. I'm thinking either the flasher module, or the combination switch.
5067076
derpicdn.net/img/view/2016/6/23/1185399.png
5067082
In this case, he did, but that is a good thought. Oftentimes when the customer tried to fix it first, we have to start by undoing what the customer said before going on with the diagnosis.
5067130
On the plus side, we make a decent profit on fixing them.
You’ve been in a Ford column before, haven’t you?
We legit had a customer complain that we messed up her tilt steering by replacing a steering angle sensor. We had to teach her that her column telescoped, which she apparently didn’t know. (We told her on the phone but she couldn’t follow simple instructions, so she had to bring her car by and we could show her how when the tilt lever was unlatched, you could also pull the steering wheel in and out.)
5067137
In the 90s, GM put the flasher unit in “the convenience center” (that was how it was described in the service information). Usually, if it was in the component locator at all, it’d just say “near the steering column.” Of course, you go under the driver’s side of the dash on most vehicles, and there are lots of wires and boxes and whatnot.
Things have gotten better recently; now that most of that stuff is online, they put in a lot more pictures which makes it easier to find components. But nobody’s re-written the service manuals for the older stuff, unfortunately.
5067157
Yes; I might not be entirely conversant on the higher side of the metric system, but I know what a 10mm socket looks like, and I can extrapolate what 100 of them lined up next to each other would be (approximately), and I know damn well that 6’ translates to just under 2 meters--something like 180cm or thereabouts. Or 180 10mm sockets all lined up...
5067275
That’s a valid reason.
5068079
I haven’t seen that show, but I did find this picture:
derpicdn.net/img/view/2016/10/20/1277391.png
5068264
I have seen melted fuses, actually . . . but that’s not where I’d go first on a diagnosis.
Also, there’s this little fuse issue:
i.imgur.com/EFO6pvrg.jpg
Yes, that’s always smart. Or at least verify what they said is actually true.
5068459
Pretty much everything’s wrong with mine, except for the drivetrain. Which, when it comes down to it, is what matters the most.
5068496
Lol mine is almost always electrical. Though I have metal shavings in my transmission fluid coming from somewhere. Makes my speed sensor get all funky then the tranny goes full retard on me.
5068475
The legends say that the biscuit admiral has a pony for every occasion possible on earth
5068383
i had totally forgot about the faulty brake switch, i took my 1996 f250 diesel in for ford to fix it on recall after i had the fuse jumper ford puts in only (you will love this ) i told ford i want my old one back as i had cut out the junk link they use and put in a real 10 amp fuse.
the service guy just stood there like Bambi in the head lights. i walked out side and switch my old one back in and tossed there one in the tool box for latter.
it is more than likely still there under all the stuff that collect's in a truck tool box.
5068477
Good things come from bad choices.
Yes. Sweet Luna, far too many.
... why am I not surprised?
5068495 Nah, looks perfectly fine to me
5068384
Yep, never seen him in person, but I'm sure he's approximately three men tall!
5068495
That.... that's not.... That's a war crime.
5068496
I've had to replace basically every major component on my bikes drivetrain at least once by now. Admittedly, it is exposed to the elements unlike a cars.
5068484
It's a pretty good show. It takes a more realistic approach to giant robots than most anime. For instance, the police squad the show centers around is shown to need a very large maintenance crew to keep their robots running. And one of their machines sits in the garage the whole show because it's being cannibalized for parts to keep the other two running.
5068529
That’s what did in mine the last time, too. It’s got an aftermarket alarm/remote start system, and if Chrysler electronics weren’t funky enough, toss in a Big Box Store special wired in by a guy making minimum wage...
Best solution for that (besides replacing the tranny, which is probably what it’d really need if it’s got loads of metal shavings) is invest in more and bigger magnets for the transmission pan. Catch all those little bits where they can’t do any harm. That’s what I did on my old Saginaw 3-speed after it ate the main bearing--fished out all the bits I could, and then stuck a few magnets in the case to catch what was left.
5068537
While I can’t take full credit--Derpibooru’s tagging system is pretty great--I’m more than happy to be viewed as a mythological figure of some minor note.
derpicdn.net/img/view/2019/5/31/2054451.png
5068559
I’ve never had to replace a fuse in the jumper wire, although I don’t work at a Ford dealership, so I can’t say how good (or not good) the fuse was.
I can say that I’ve seen myself Fords that have burned from the brake switch failing. One of our customers lost a pretty nice (and as a Chevy guy, it pains me to say this) F-150 for that reason.
Legend has it that Texas Instruments--who designed the switch--were told that it was going to be used intermittently, whereas the Ford engineers changed things around so it was in continuous use, and not rated for that.