Improper gear ratio
 

For several weeks now, I have had a problem with the car (2000 S 40).
From a stand still position, the car reluctantly accelerates. After a moment, it gets going.
A couple ofsensors have been replace, butthe problem persists. And this is inconsistent; some days the car driveslike a new car - smooth, quick acceleration - other days not.
Dealer says the diagnostic code is improper gear ratio and I need a $3K transmission.
With the inconsistency of the problem, I cannot help but feel it is electronic, not mechanical.
Is anyone experiencing this type of issue? Suggestions?

Ws S 40 needs help!

RE: Improper gear ratio
 

Haven't seen that before on the S40.
But maybe electronic.

RE: Improper gear ratio
 

Hello,

I drive 1994 850 and once had "Incorrect Gear Ratio", accompanied by the flashing arrow on the dash & CEL. My problem was low transmission fluid, by as little as a half quart.

Check to see if the fluid is at proper level. The procedure should be in the owner's guide, but if you don't have one, let me know and I'll explain it to you (I posted one recently in the 850 section, so I'll find it, copy & past it for you).

Good luck.


JPN

RE: Improper gear ratio
 

JPN,I do not see reference to a specific procedure, so I would like to take youup on your offer. I might add a little additional info about my S 40 experience. The car has not been driven since my posting, that is until tonight. It started out driving fine; not flashing arrow or check engine light. I got out on the highway, still smooth until I got it up to 60 mph. It seemed stuck in gear for a brief time, then with a slight jerk, shifted.
At any rate, thanks for sharing your experience.I'm hoping that I have anoutcome similar to yours!

Ws S 40

RE: Improper gear ratio
 

Hi,

I'm sorry I did not reply to your last post sooner, somehow the thread was not in bold as usual so I didn't know there was another reply until now.

Anyway, here's the general procedure for checking the tranny fluid level:

1. Drive your car for about 15 minutes, so the fluid gets to normal operating temp.
2. With the engine at idle, shift into PARK and apply parking brake fully.
3. Now, from PARK, shift through ALL detentes (P-R-N-D-3-L), pausing about 3-5 seconds at each detent. Do this with foot brake applied as well. Do the same in reverse direction (L-3-D-N-R-P).
4. Open the hood, locate the tranny dipstick. Pull it out and wipe clean and re-insert it, making sure that there is no foreign object, not even a little tiny one. Even if a tiny bit of foreign object is allowed inside the tranny, it'll render it useless so use caution when re-inserting the stick.
5. Pull out the stick again, and check on the "HOT" side of the stick (it should have a writing on it), and make sure that the fluid is between the "MIN" and "MAX", or between two lines.
6. If low, add fluid just enough to bring the level between the lines. You might want to add closer to "MAX", but not above MAX. If overfilled by a little, it is ok but if more than a half-inch, drain some fluid.
7. Test drive to see if there is an improvement. In my case, a half quart of fluid added solved all problems. If this does not solve the problem, another cheap alternative is to have the fluid totally flushed. There might have been a tiny FOD (Foreign Object Debris) already introduced in the tranny so this may help.

The correct fluid is "Dexron-III/Mercon", about $2-$3 a quart at an auto parts store. If the tranny acts fine some days, I doubt you need another unit. Like Tech said, it is probably electronic control trouble. If all the above fails, try using synthetic tranny fluid, it may do some trick (look for synthetic Dexron-III/Mercon). Diagnosing modern cars is like diagnosing a human body (not kidding), so I pay utmost respect to people like Tech.

I hope this helps. Again, I'm sorry my reply has been delayed.

Best wishes,


JPN