I'm gonna try to explain this as good as I can. I don't know much about cars, so try to be patient with me. Here's the deal. I have a 1997 Honda Accord LX (4-cylinder engine, automatic transmission), 140,000 miles.

When I first bought the car, the guy who sold it to me informed me that it needed a VSS (Vehicle Speed Sensor). Which was true. The speedometer didn't work, nor did the Cruise Control. My girlfriend's father (who's a professional mechanic, and also went with me when I bought the car to check it out) put in the VSS for me and the Speedometer worked fine. But the "Check Engine" light was still on. After hooking the machine up to it, I found out that I needed an Input (Mainshaft) Speed Sensor. So my gf's father replaced that as well. After it was replaced, the Check Engine light went off.

Now here's the issue. When my gf's father replaced the VSS, he told me that one of the circuits on the part that plugs into the VSS was corroded. But now...my car shifts funny and the speedometer goes all over the place. For example, I might be doing 45 MPH, and the speedometer will just jump to 80-100 MPH and keep bouncing back and forth. And when this happens, the car begins to jerk while accelerating. While idle, the oil light flashes on and off (I have plenty of oil in the car). This has happened for 3 straight days. My gf's father is out of town, so I can't have him look at it. I suspect that it has something to do with the corroded circuit in the VSS, but I don't know about cars, so I could be wrong.

Since I've bought the car, I've had the oil changed, installed new wires and plugs, and also, the transmission fluid looks to be in great shape.

Any idea what this could be?

 

When the speedometer starts jerking, does the check engine light turn on or the D4 light start flashing? If so, have the codes scanned at a parts store like autozone. Your connector is behind the ash tray. The codes start with the letter P and have 4 numbers, like P1234. Also, will the cruise control work when your speedometer is malfunctioning?

You didn't specifically answer this, so is the oil level correct on the dipstick? With the engine off, pull out the dipstick, wipe off the oil, then reinsert. Pull out dipstick then check that the level is between the two dots. Not trying to be sarcastic, just trying to be thorough.

 

There are only two wires to the VSS connector. If they are corroded or damaged the signal may be too weak to be correctly interpreted as vehicle speed. Lack of vehicle speed input to the transmission control unit (computer) can lead to hard/sloppy shifts and other problems.

If VSS circuit is a problem, the Check Engine Light will come on and there will be a code set (Code 17 -OBD1 self diagnostic code) or P0500 (OBD2 scanner code). Also D4 light may flash indicating transimission computer code for VSS fault (Code 4 or P1791). If a circuit fault appears, it must be corrected to fix the problem.

Oil pressure is likely a separate problem. I would have the oil pressure checked w/ a pressure gauge to confirm idle oil pressure is good, and if good replace the low oil pressure sensing switch on back side of engine.

good luck

 

I didn't pay attention to the D4 light when it jerked. If it happens again, I'll do that. I haven't tried the Cruise Control either. During all of this, the check engine light doesn't come on.

I checked the oil a week ago, but I'll check it again just to be sure. Thanks for your contribution.

Interesting...
I wondered why the oil light would flash while idle, that might be it. I'll get someone to look at that. Thanks again.