Shifting problems and blinking S light...

[SolidSteel144]

Hello, my 91 Accord with an automatic transmission is having problems shifting the first couple of gears. The S light blinks and the speedometer doesn't work correctly. What could be the problem?

Thanks in advance.

[old honda tek]

sounds like a bad speed sensor ,when the speedo stops working while u are driving it will cause the d4 liht and s light to flash and also the check engine light to come on. you can replace just the electrical part . they have it at auto zone....

[SolidSteel144]

sounds like a bad speed sensor ,when the speedo stops working while u are driving it will cause the d4 liht and s light to flash and also the check engine light to come on. you can replace just the electrical part . they have it at auto zone....

I've replaced it and it didn't fixed the problem.
It could be anything since the previous owner didn't really take care of it.

[deevergote]

The non-working speedometer probably IS the VSS. However, the flashing S light indicates an error code (or more than one code) from the TCU. Pull the code, and it will tell you what is wrong with your transmission. Fix that, and you'll fix your shifting problem. (any time someone mentions a flashing D4 light, take it to mean the same as your S light... the 92-93 models don't have the Sport mode, and therefore no S light... so the error codes come from the D4 light instead.)

http://www.cb7tuner.com/vbb/showthread.php?t=21259
Here, I was nice and dug up the codes and procedure for you. For future reference, this kind of stuff is located in the "sticky" thread at the top of the Technical section.

[Potatoswatter]

Don't be too hard… the VSS should set a TCU code.

SolidSteel, you replaced the VSS and it didn't fix the speedometer? Maybe double-check that repair.

[deevergote]

Should the VSS affect shift quality?
I suppose it could... though checking that code would be the only way to see what's really wrong.

And if the VSS didn't fix the speedometer, then either the new part was faulty, the speedometer itself is faulty, or there's a problem in your wiring or connections.

[SolidSteel144]

I'll try to check it out, I've noticed the blinking S light usually pops up while actually driving the car.

[deevergote]

It doesn't matter when it pops up. Follow that procedure to determine what the error code is, or we really can't help... unless you want us to run down the list of possible "bad shift" culprits and tell you to replace them one by one... I know I'm not made of money, and I doubt you are either. Best to find out what is ACTUALLY causing your problem.

[SolidSteel144]

It doesn't matter when it pops up. Follow that procedure to determine what the error code is, or we really can't help... unless you want us to run down the list of possible "bad shift" culprits and tell you to replace them one by one... I know I'm not made of money, and I doubt you are either. Best to find out what is ACTUALLY causing your problem.

Most agreed... I'm about to test that out.

[SolidSteel144]

I got 4 quick blinks:
CKP - crank position sensor

Which is the..?

I'm not sure if I read it correctly.
The 4 blinks were consistent, but the first one is faint while the remaining three were full brightness.

Correction:
I got 4 blinks from the TCU
I still need to get the code from the CEL.

[deevergote]

Be sure you're looking at the TCU codes, not the ECU codes. (counting the S light flashing, and looking at the TCU codes at the bottom of the first post, not the long list of ECU codes above it)

The code is... hey, whaddya know... VSS. (sorry old honda tek... I guess you were right afterall...)

Is that the only code? Multiple codes will have a pause between them. If the 4 flashes keep repeating, then that's the only code. If that's the case, unplug your battery for a few minutes to clear the code, and see if it helps. If it doesn't help, assume your new VSS is faulty, installed incorrectly, or there's a wiring issue. You might want to try borrowing someone else's TCU and swapping it out, as they can occasionally go bad.

[SolidSteel144]

I've tried multiple TCU's and this one seems to be the closest match to the original. I highly suspect that it's a wiring problem and that there is a short somewhere. Much appreciated, I'm going to have someone take a look at the wiring for it.

[deevergote]

What do you mean "closest match to the original"? If you're using a TCU from a 1991-1992 Accord of the same trim level (the trim level really doesn't matter much), they should all be identical. I don't mean try a different model ECU, I mean try another of the same, as this one may be faulty.

Check your wiring, clean the connection to the VSS, and don't rule out the possibility that your new sensor could be bad. It does happen.

[SolidSteel144]

What do you mean "closest match to the original"? If you're using a TCU from a 1991-1992 Accord of the same trim level (the trim level really doesn't matter much), they should all be identical. I don't mean try a different model ECU, I mean try another of the same, as this one may be faulty.

Check your wiring, clean the connection to the VSS, and don't rule out the possibility that your new sensor could be bad. It does happen.

Who ever install the other speed sensor did it very wrong. I just found out it was loose (improperly installed). Hmm...