Diagnose my car problem over the internet

I have a '91 Ford Ranger.

About half way into my 2 hour commute this morning, I noticed that the dashboard lights were dim. A few minutes later, the battery warning light flickered on. It stayed more or less on for the next hour, finally switching off after I got past a particularly nasty traffic accident (overturned manure truck). In addition to the dashboard lights, the windshield wipers and turn signals seemed sluggish, but maybe I’m seeing problems where I want to.

What has me confused is why I would have electrical production problems while driving. Shouldn’t all the power be coming from the engine, not the battery? What is going on and how panicked should I be?

Another question:
The truck has 4 gears and a 5th gear labled “O.” Since I’ve been doing a lot of highway driving lately, I was using O as a true fifth gear for obtaining speeds at 70 mph (the legal limit here) while maintaining the RPMs between 2-3. Is this okay to do? Or is that gear for towing or something? The owner’s manual was not helpful.

Thanks.

I have a '91 Ford Ranger too :).

I don’t drive it much though; it has about 110K miles on it.

Anyway, it sounds like your alternator is dying. That’s the classic symptom: while on the road, the stuff that normally runs off the alternator is starting to draw off the battery, and everything starts getting sluggish.

As far as using O (Overdrive), that’s what it’s for, ~70mph driving.

I don’t know if you have a different transmission, but my '91 ranger has a 5 speed standard transmission. There is no “granny gear” and the top-right one is fifth.

Oh, yay! A new car problem that I can now diagnose from personal experience. Just what I needed.

On the plus side, I’m not ruining the transmission.

Thanks, minor7flat5. Off I go to price new alternators.

I’d have it bench tested first, to rule out a wiring issue. Batteries plus will do it for free.

I have a '91 Ford Ranger. <<=== This is your problem! LOL

Seriously, it is most likely you’re alternator, but before you rush out and buy new one there are other possibilities.
A battery that will not take a charge anymore, wiring problems, faulty relays, fuses, or circuit boards, or it may be a simple as a loose or worn serpentine belt.
If you don’t have any idea how to diagnose it yourself you should take it to someone who does. They can load test your batteries, bench test your alternator, etc…

I have a '91 Ford Ranger. <<=== This is your problem! LOL

Seriously, it is most likely you’re alternator, but before you rush out and buy new one there are other possibilities.
A battery that will not take a charge anymore, wiring problems, faulty relays, fuses, or circuit boards, or it may be a simple as a loose or worn serpentine belt.
If you don’t have any idea how to diagnose it yourself you should take it to someone who does. They can load test your batteries, bench test your alternator, etc…

As far as the Overdrive goes, it is a gear with a ratio specifically designed for driving at high speed over long distance at low engine RPM without frequent acceleration or decceleration. You should not drive in it all the time… that’s what the D is for, but your Automatic Transmission Control shouldn’t use it until you get up to speed. It will cause unneccessary wear on you transmission if it is engaging and disengaging all the time. Have you noticed it hunting for what gear it should be in at certain speeds?

Can I strongly recommend that everyone read their owner’s manual? All this info is included and you should know it or be able to look it up. It will save you tons of time and money believe me!

Can I strongly recommend that everyone read the OP, like the part were I mention that it’s a stick-drive transmission and that my owner’s manual didn’t talk at length about which gear was which the last time I looked at it? :wink: :smiley:

No harm done. I do appreciate everyone chiming in to help.
And don’t worry: anything more complicated than and oil change and I have The Professionals take care of it. I’ll make sure they do the standard diagnostics first. Just figured the Dope could tell me if this was a “get it looked at when you can” problem or a “your car will explode on the freeway” problem.

Isn’t a loose or worn belt more likely to present as screaching/sqealing when the car is running?

Nah, won’t expolode on the freeway, if it’s the alternator and it drained your battery, you won’t make it out the driveway in the morning.

Not necessarily. It won’t squeal if it is dirty/oily, too old, or too loose.
There are those who will keep driving when it squeals, and then when it stops they think the problem has gone away.

Diagnostics done: It is the alternator.

On a scale from beginner to Nascar, how difficult is it to replace an alternator?

The last time I did that I was in the service, had minimal tools, and I did it in the parking lot. It was a pain in the ass.

If you are a car person, it is a fairly simple job; if you are an average joe, somewhat handy, who is just trying to save a buck, it will take awhile. It’s not too difficult, though.

I never changed an alternator on this particular truck, but I think that the engine has multiple belts (not a serpentine belt). You might have to take off a couple of belts to get at the one for the alternator.

Note that all of the bolts will be rusty and will fight you.
Don’t crawl under the truck to loosen anything without wearing goggles – flecks of rust will fall in your eyes (as I found out on a different truck).

Besides unhooking everything and hooking up the new one right, you still have to retension the belts. Shade-tree mechanics often used a broom handle to wedge the alternator away from the engine while tightening up its bolt.

If it’s a serpentine belt (single belt with multiple "v"s that drives all accessories), I have never touched one of those. Someone else can answer that one.

Update:
I just got home and went over to my '91 Ranger, started it up for the first time in 3 months, and popped the hood.

It has two belts, the front one drives the alternator and A/C compressor; the rear belt drives the power steering pump.

I have to honestly say that if I had to replace a bad alternator on this truck, in the condition that it is in, I would pay to have a pro do it. It just isn’t worth the hassle to me.

Everything is rusted, and there is a whole lot of crumbling tubes/wires/etc. in the vicinity that I might mess up in my banging around, It’s tighter in there than a traditional old-school pickup truck.

Whatever your choice, good luck!

Thanks for the recon, minor7flat5. The idea of screwing up the belt tension is enough to send me to a pro.

I’m fairly certain every car has some sort of sensor that tells it how much money you happen to have in the bank, so it can break something just expensive enough.

As an average handyman Joe with no automotive experience, I replaced the alternator on my wife’s '89 Nissan Sentra. It wasn’t too hard, but it took me several hours and uncomfortable contortions to get my arms wedged in there. I had one of those repair books you can get at the auto parts store to guide me.

It’s not hard at all, IF you can loosen the bolts that hold it to the bracket. My 91 ranger has the 2.9l engine, and the hardest bolt to get at is the bottom one which you need to access from the rear of the alternator. This requires a short extention and a rachet (I can’t recall if the socket you need is 15mm or 16mm). This is a somewhat long bolt and it takes a while to back it out all the way. If you can access this bolt and loosen it, then you can do it yourself. If you can’t, take it to a mechanic. This bolt on my 88 ranger (yep, I have two of them) is frozen and when this alternator fails, it’s going to the shop.

Ditto what minor7flat5 said. I’m pretty sure the “O” is for overdrive and the flickering lights all happened to me as well in my Mazda MX-6. Basically the alternator stops charging the battery and providing “through” power to your car while driving it. Although depending on what parts are going out you get similar but unique “experiences” with a dying alternator.

Mine wouldn’t close the circuit so it gave me direct power but didn’t charge the battery. The more things I didn’t use like the fan (it was summer ;( ) , the radio, the lights (I drive with my lights on ) the more the car would behave itself, but try to roll the window down (electric) and the car would sputter and hiccup and the dash lights would go crazy. I replaced it and voila everything was fine- only I was just barely able to not have this work done before I got a newer car which also after 50K lost it’s alternator… sigh anyway- take the back roads and try to not use any more electricity than necessary on the way to the nearest/cheapest garage… cost me something like $350 to do -grrr… good luck

(I started another thread to express my frustration, but I’ll repost the info here)

The truck died on the highway last night. It just stopped responding to the accelorator and gradually rolled to a stop. For the record, slowing down on a busy highway when your hazard lights don’t work earns you a lot of snotty looks.

Paid $100 for a mechanic to confirm that it is the alternator. Trying to figure out exactly what to do next.

Thanks for the info, everyone!

If you decide to replace the alternator, try to find a Bosch brand one- I trust the quality of them over the many no-name brand ones. With my last alternator Itried to locate another Bosch, but the service people basically had a roledex of names straight out of the yellow pages and grabbed the first one they could find to fit the needs of my car. Later when I got home I used the store locator online and found one at NAPA auto parts… gees, car shops are so in the stone age…