I have a 1991 accord ex, 160,000 miles. I just bought the car 2 weeks ago for $2100, and i had only driven the car for about 50 and all of a sudden a green s light started to blink and my speedometer stopped working. The engine light comes on too. Does anybody have any suggestions on what the problem is and how much it will cost to fix.
Also, what does the "Sports" do on the shifter?

You need a speed sensor.
http://www.d-a-p.com/shop/scripts/prodList.asp?idCategory=1185

These are VERY common questions. Did you do a search first? If not, please do so.

These are VERY common questions. Did you do a search first? If not, please do so.

I have searched a little bit, and there have been a few different answers. I read that one guy replaced that, and it didnt work.

Also, what does the "sports" do?

Also, what does the "sports" do?
Nothing but waste gas...

The "S" awitch changes shifting points so it shifts to the next gear at a higher speed.

If you have an OBDII (96+) most Autozones have a service where they will plug in a scanner to your ECU and retrieve the codes for free. If you don’t have this service available at your local Autozone, or you don’t have a local Autozone, or you have a pre-96 car, you will need to pull the code yourself. (You can take it to a dealership to have them pull the codes, but personally, I can think of a thousand better ways to spend $70/hour).

To learn how to pull your own codes, go here and read everything:
http://www.hondapitstop.com/accord/technotes1/engine/error_codes/error_codes.html

If for some reason that isn’t sufficient for you, you may want to look at this:
http://www.automotiveforums.com/vbulletin/showthread.php?t=19102&highlight=P1259+VTEC+system+malfunction

Now you should have a code…and you probably want to know what the code means, so check out these pages. Between these 4 pages you will DEFINANTLY find your code and what part of the car it refers to.


http://www.automotiveforums.com/vbulletin/showthread.php?t=19102&highlight=P1259+VTEC+system+malfunction

http://www.automotiveforums.com/vbulletin/showthread.php?t=369819&highlight=P1259+VTEC+system+malfunction

http://www.hondaswap.com/forums/index.php?showtopic=29806

http://www.hondata.com/techecucodes.html



The flashing ‘S’ light:
Some Automatic Accords (90-93) came with what in my opinion is a pointless feature: The sport shifting mode. There is a button on the shifter for sport shift. The idea behind it is that when activated it will prolong the shifts, and get the rpms higher, so when it does shift, it is higher in the powerband...fine in theory, but after multiple trips to the track, I can tell you this feature made no difference, ON or OFF. Switching this feature on, causes a green ‘S’ light to illuminate on the dash.

However, some of you may have experienced this light or the ‘d4’ light flashing, regardless of your sport shift being turned on or off. This is caused by 2 things, both cause similar symptoms, so make sure you diagnose the problem correctly the first time. The VSS (vehicle speed sensor) or the TCU/TCM (transmission control unit/module) has or will die soon, and is trying to warn you.

VSS(vehicle speed sensor): Hopefully, you took the advice above and scanned the ECU for codes. If it is your VSS causing the problem, you will get a ‘17’ code. If you didn’t scan it for codes, you will notice problems with your tach, your speedometer, your cruise control, they will work intermittently if at all. If this is the case, check these out:
http://www.cybertrails.com/~bestinthewest/autotips/999VSSTestLocation.html
AND
http://www.hondapitstop.com/accord/technotes1/engine/speed_pulser/speed_pulser.html

If you buy a new speed sensor from the dealership, expect to pay WAY too much. Most people opt for a used one, either from another board member selling parts from their old Hondas (like I did), or going to a junkyard and getting it for $5-20. At a dealership, it could run well over $100. If you do some searching online, I found some remanufactured ones for ~$50 that came with some sort of warranty, but I’m sorry, I don’t recall the website.


TCU/TCM (tranny control module/unit): Similar symptoms as the VSS, yet this may cause shifting problems, you may lose 4th gear, and you wont have issues with cruise control/speedo/or tachometer. If you do a search for TCU or TCM, you can find quite a bit of info, but basically it is a little electronic box under the kickboard of the passenger seat (where the passenger's feet would be up near the dash) You pull back the carpet, and behind that metal shield there are 2 computer boxes...I forget which is the TCU (I want to say the one on the right, but double check that before you take my word on it). Anyway, the dealership will charge huge amounts of money for a new one. So go to your local junkyard or ask around on here. Typically you can find a used one for $50 or less. It takes 15 minutes for the average person to swap.

I read that one guy replaced that, and it didnt work.
Maybe so, but the fact that your speedo gave out at the same time is the dead giveaway.

Also, today when i was driving on the interstate, I was going around seventy and then when i went to sixty my speedometer stopped working, then i accelerated back to 70 and it started working. I did this a few times

So fix the problem, get a new speed sensor.