I need some back-up, folks. I was telling a friend about a Chevy Celebrity I had a long while back that had an unusual defect-at random intervals, the odometer would roll back on it’s own while I was driving it. He claims that this just isn’t possible, and I’m having trouble finding other tales of this happening on the interwebs.
The old-fashioned mechanical type? It really doesn’t sound possible at all.
My first car was a VW Beetle. I could (and did…statute of limitations) remove my speedometer/odometer cable. I would reattach it when I took the car for inspection.
Not a rollback, and not a defect.
Nope, I was just offering evidence that odometer/speedometer cables were very different in the past. I cannot imagine intermittently using the odometer on any car I’ve owned recently.
I had an 86 Mustang that if you drove in reverse it would roll back the odometer.
I’ve never heard of your problem, but the old cables would break and twist, I can see something like that happening.
You think the OP is lying?
While I havent had the time traveling odometer thingy, I’d had a couple of computer, mechanical, and electrical things happen to me that I would have nearly bet my life on being physically “impossible”. And I say this as a guy who used to be pretty up to speed on computers, is pretty mechanically inclined, and has a physics degree with a pretty good “feel” for how things work in real life.
I don’t doubt the OP for a second myself (unless of course its some kind of “it happened once when we were bar hopping one night” or “when I was four years old my grandpa showed me this…” story).
Oh, and I very vaguely remember either seeing this happen in somebody elses car a time or two or having somebody telling me this happened to their car as well. But that memory is now so vague I would place nearly zero stock in it.
What exactly happened, was it a particular counter that didn’t go up or did it actually run backwards? If, for example, the hundreds counter wasn’t always engaging when the tens counter reached zero you could get this effect.
Maybe the odometer was purchased at Walmart?
WTF? 
No. Perhaps it was one of the newer digital displays and there was a component malfunction. I asked for clarification because mechanically I can’t think of how it could randomly travel backwards.
Later model (1987 and up, I think) Celebrities had no speedometer cable; they received input from the ECM unit, and are known to have speedometer weirdness when that unit is failing. Other symptoms included stalling, not starting, rough idling, and turning into a newt.
Later model Celeb, I believe, and it also had the rough idling problem. The odometer actually rolled backwards as I drove, at quite a clip, not matched to the speed of the vehicle at all.
This stuff can happen. I have a 2005 Chevrolet Silverado. It has a digital odometer/hour meter for the engine. One day I was looking to see if I had gone over 2000 hours yet, only to see that I had 17 hours on my engine. Ever since then it sort of decides that it only has 150 hours, 75 hours, 12 hours… Odometer works fine and everything else does as well.
AFAIK there isn’t a way to reset the hour meter as it is used much like the odometer for service intervals, etc…
So screw your Delorian, Doc Brown. The Silverado has four doors!!!
In 1985 I designed a stepper driven odometer for the Ford Escort. The stepper motor could turn either direction. I really don’t remember enough about the logic circuit to say how an intermittent fault could have caused it to run backwards, but it might be possible for that type of odometer.
I have it on good authority (I think a documentary from the 80s) that you can’t roll back the odometer of a 1961 Ferrari 250GT merely by running it in reverse.
My 2000 Frod Fucus’ electronic trip meter (that I always reset to zero with each fill-up at around 200) sometimes (used to) reset itself to zero. I visited a NC Mazda dealer once to look over a used Prestige and checked its odometer. It had been traded in with exactly 25,000 miles on it. Sure it had.
Maybe that was the mileage limit on a lease and someone was very determined to get their money’s worth.
The odometer of my (now deceased) '91 Grand Prix, near the end of its life, had a habit of randomly going “forward” at 600 mph, in park, idling at the usual 5-800 rpm. Once in a while, it would do the same, in “reverse” at a slower speed. My friends and I would cheer it on. Unfortunately, it went “forward” more often, so any trade-in value was lost as the thing whirred like a dental drill.
Could the documentary have been the movie Ferris Bueller’s Day Off
I had a '95 Harley Sportster. The speedo was the old fashioned needle with numbers type, but the odometer was an electronic digital display type like this.
I had installed some Screaming Eagle spark plug cables. They didn’t fit right and while I was riding sparks arched out from the plugs and lit up the engine like freaking Frankenstein. ZAP! Startled the living shit out of me.
The electrical surge blanked out the odometer. No numbers, nothing. I turned the engine off, pushed it home. I put the original cables back on the bike. Turned the power back on and the odometer said 400 on it. It continued to work properly after that, with no indication that anything had happened to it. Prior to this happening the bike had about 5200 miles on it. When I sold it I told the buyer what had happened and that the bike had 5200 more miles on it than the odometer showed.
Point is, odometers are mechanical things, and mechanical things can fail, break, not work properly, etc… So the OP isn’t all that unbelievable to me.
You had a car that could go 600 miles an hour while it was in park? How fast could it go in third gear?