93 Caravan dies on the road, not in the shop

I have a 1993 Dodge Caravan (4 cylinder), and drove it up to spend a week along the northern part of Lake George (NY), out of cell-phone range. One day when I was on the road in the middle of nowhere, the engine died. When I tried to restart it, the engine cranked but did not catch. After about 10 minutes of useless looking under the hood, I tried again, and it started and ran fine for the rest of the day.

A few days later, I started out for home, and after about 1/2 mile, it quit again. I was near a telephone and was able to call a tow-truck, and even when the tow truck got there, it wouldn’t start. I had it towed 30 miles to a mechanic, and once it got there, it ran fine.

I left it with the mechanic for a few days, and he could not reproduce the problem. He had someone plug something into the computer, but it showed no problem.

I finally drove it home (~200 miles), with no problem, and left it with my neighborhood mechanic for a week. He was unable to reproduce the problem, either. He said he couldn’t see anything that seemed to need repairing or replacing, and didn’t want to go replacing things at random.

Expert opinion was mostly in favor of fuel pump problems, but some thought it might be ignition.

I have never had this problem before – in fact, I have never had engine trouble with this car before. Aside from one or two incidents with a dead battery, it has always started up and stayed up fine.

The only thing I can think of that might be a factor is that the week I had trouble, I was parking the car outside, next to our cottage, on dirt and under pine trees. At home, the car spends most of its time inside a garage. However, we’ve been staying there almost every year for quite a few years now, and never had this trouble.

The other thing is that it’s been a while since the last tune-up; however, if that were the problem, I would think that the mechanic would have noticed something.

I would look for a faulty ground connection. It sounds like a loose or dirty wiring connection.

Possession of the proper wiring schematics will be beneficial.

You mentioned there were expert opinions denoting fuel pump problems, was anything done to allay that thought?

I have an update on this problem.

It died again, while I was going 60 miles per hour.

The engine went dead, as if I had turned off the ignition,
and the speedometer went to zero immediately, even
though I was still going 60.

However, the oil light went on, and the radio continued working,
so it was not as though the entire electrical system quit.

I’m assuming this is an electrical problem, since the engine didn’t
sputter to a stop as I would expect with fuel starvation, but just quit cold.

I mentioned this to my mechanic, the one who spent 5 days
tearing the car apart to look for problems, and he didn’t
see how this additional datum – the speedometer quitting –
helped things.

I don’t know whether this car has a speedometer cable, or
a speed sensor that goes into the computer and on to the
instrument panel, and the mechanic didn’t say.

Anyway, does this help?

I assume you have the 2.5L engine. These engines were known to have flaky hall effect sensors in the distributor that would fail as you describe in your post.

Go to allpar.com for lots of information about your car.

I would also suspect the ASD (auto shutdown/fuel pump) relay. I had a 90 Dodge Spirit, 2.5 engine, that had the same symptoms you’re reporting. Replacing the relay fixed the problem for me. The part isn’t that expensive, $30 -$50, and is easy to replace.

I went to www.allpar.com, they listed about a half-dozen possibilities.

What they don’t explain is why the speedometer would quit when the problem
arises. Especially since there are places that will sell me a new
speedometer cable, which suggests that it’s a mechanical, not electrical
speedometer. (Or else they’re scams.)

Normally, the speedometer works even with the engine off, IIRC, but I could
test it out.

I understand your point about the speedometer. I’m trying to suggest the most common intermittent failures known for that engine.

Check for a big ground lug on the end of the cylinder head (the end where the transmission bolts to the engine) It is held in with approximately 12mm bolt, and may be difficult to see under the wiring harness. Make sure the bolt is tight, and that the wire is secure in the lug.

"The engine went dead, as if I had turned off the ignition,
and the speedometer went to zero immediately, even
though I was still going 60.
It looks like the speedometer drive circuitry (vehicle speed sensor) may be the cause of the problem. The vehicle speed sensor (vss) is mounted on the transmission. It sends its signal to the engine computer. The engine computer sends the signal on to the speedometer.
Is the check engine light on, or does it flash? Check the wiring (with a multimeter) and the VSS. If there is a check engine light, a repair manual will show the repairer how to get the trouble code. We can decode the code and give advice.

I agree with Markmast. I have 97 3.0 that died at random with no codes. It was the crank position sensor(cps) which as Markmast said uses the hall effect. It cost about 35 bucks and did it myself in about 30 minutes. Good luck

At the parts store site, I don’t see that your Caravan has a crankshaft position sensor. It, instead, has a distributor which will fill that function. http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?fromSearchPage=true&pageId=0900c15280215c6a&partName=Component+Replacement+and+Testing&partId=0900c15280215c6a
You could swap the ASD Relay with one of the other relay in the relay box. Check the horn relay as a match.

Update: about 6 months to a year after I wrote this, it got to the point that it was quitting every 5-10 miles. I brought it in to the dealer, they said it was <Ta da!> the Hall effect sensor. Problem solved, or so I thought.

Then it happened once ain, about a year ago. Pulled over turned off the car, turned it on, it started right up. But no problems for maybe 6 months, when it did it again.

Then, last Saturday, I was driving up the parkway (50-60 mph, non-stop), and at about 30 miles, bang, it quit again. Pulled over, turned off, waited 5 seconds, it started right up. 30 miles later, the same thing. This time, a cop stopped next to me and started interrogating me about it, so I forgot to turn it off. It wouldn’t start. I turned it off, turned it on, and it started right up. I gave up on my trip, turned around, drove back, it was working fine. Stopped for gas 20 miles later, went back on the parkway, and 30 miles after I left the gas station, it did it again.

I’m going through the usual list of mechanics, who can’t find anything (so far.)

Should I assume it’s the Hall effect sensor again, and just tell the mechanic to replace it?

I tend to think there is something else going on electrically besides the hall effect sensor. It would be nice to know if the ignition system is working ok when this trouble happens. I suspect there is a bad connection somewhere that is causing the trouble. You may be able to tap on suspected trouble spots using a screwdriver handle and make the trouble happen. Perhaps even disconnecting and reconnecting connectors under the hood may solve the trouble. If the speedometer is still quitting when the trouble occurs it may be a good idea to investigate the transmission control unit since the sensor ties to it along with the crank sensor. I would make sure the power to it is ok.

AMMinNY — "Should I assume it's the Hall effect sensor again, and just tell the mechanic to replace it?"
That is what I would do. If the CPS fails the fuel pump relay will open (a safety feature to prevent fuel flow if the car is in an accident and the engine stops running with the key still in the ignition).

Well, it happened again last week (it’s taken me that long to get my account to work again.) I was driving (in the rain, if it matters), and it quit maybe 15 times in a 20 mile trip. I’d be driving along (or coming to a stop), the speedometer would drop to zero, the engine would quit, and everything else keep working. I’d put it in neutral, turn the ignition on, and restart it, and it would be good for anywhere from 1/4 to 4 miles.

It has been fine since then.

I’ve decided it must be the computer, because it acts just like a computer crash. It crashes, I turn it off and on to reboot it, and it works fine until the next crash. It also explains why there are no “codes” – after all, what generates and stores the “codes”?

Anyway, I went back to the shop and told them to replace the computer. Hopefully, they’ll find one in the next week or two.

BTW, when I tried googling “1993 Dodge Caravan Computer”, ECMs kept coming up. Is this computer the same as an ECM? It does seem to be glued to some kind of air intake on top of the left front wheel well.

Try hellokit’s advice, are the conditions related to weather, like rain? Try to correlate as many coincedences as possible.

I have a 3.8 liter V-6 multi-pt Fuel inj 1999 Oldsmobile 88 Electrical Problem with 125k miles
The Engine Cuts Off As Soon It Gets To Operating Temp (198’)
I can drive for about 20 minutes in traffic - the it cuts off…
Engine restarts almsot immediately.
I’ve been turning the engine off and coasting on downhills and red lights. That cooling is enough to restart
each time.
The mechanics ‘fix’ it, but I found out they idle the car for 15 miuntes and claim there’s no a problam.
So I got in the car, drove it 'round their lot and it shut down. (& re-started after a few minutes).
So it’s not just the hot engine, the car has to be ‘in gear’ to shut down.
Is that an important difference in figuring out the problem?.

I doubt changing the ECM, or possibly the PCM in your case, is going to make a difference in the trouble you are experiencing. The trouble is most likely due to a bad connection to power going to the transmission control unit possibly. It could be the CPS sensor also as others have stated but I would think there would be a code generated if that is the case. To find the trouble it might help to tap on suspected trouble spots using a screwdriver handle since the trouble appears it may be sensitive to vibration. The best clue to the trouble seems to be with the speedometer not working and I think that it depends on information from the transmission control unit. There is the restart issue also as it doesn’t always restart right away. That could mean the issue is with the CPS or the ignition system. It would be really nice to know if the ignition is working when the trouble occurs.