Clean. Mags. Interior nice. Engine clean. Runs swell. Transmission problem(s)!

1999 Honda Accord 4 cyl Automatic will not move in first gear once warmed up - Works OK cold. Took out solenoids, tested, and cleaned all. Only one filter had any trash and wasn't totally clogged. All tested to work. When I put them back in and ran the car, it shifted normally when first driven, as though this fixed the problem - but D4 light was flashing. Once it was restarted, the D4 light no longer flashed and shifting went right back to not having first gear. Other gears shift normally. Have to manually select second to get going once the car is warmed up. It will not go when first is manually selected either. It can be put in first but barely can move much at all even when revved. Acts like torque converter has no fluid when warmed up or that fluid is too light a weight. First gear only.
Just got car for junk price, from "lil' ol' lady" who didn't drive it much and knows nothing about it or what she might have done or had done.
Gammlin that it can be fixed without spendin a fortune.
Reset ECU. No change.
How will overfilling affect this? Dipstick shows it to be WAY over full. How much I can't tell.
Engine light is on. Transmission fluid looks like new - red and clean - no sign of debris. Don't have any idea of what kind of fluid is in there.

 

If the CEL/D4 lights are illuminating, get an OBDII code reader and pull the codes.
Do not clear the memory as you will lose any codes that would pinpoint what the problem is.
Being a speed density system it will take a while to get a more accurate code, don't 'clear' the CEL/D4 warning lamps without retrieving the code(s) first.

 

The engine maintenance light is on and has been on.

First gear does not work once the engine (or tranny fluid) warms up. Barely moves at all when revved. No noises, just doesn't go. D3 and D4 seem normal except for first gear.

 

Took car to parts house and had them run their scanner. It returned the following codes:
P1491 - Emissions
P0705 - Range sensor circuit malfunction
P0706 - Transmission Circuit Range/Performance

These seem to indicate Neutral Safety Switch problem.

 

Neutral Safety Switch is on the side of the transmission behind the passenger side front wheel. Once the wheel is removed, there is a cover, held by two bolts with 3 more bolts to hold the wiring to the transmission.

The switch plugs in near the top of the engine. The release for the plug is on the underside of the plug, naturally enough.

Swapped the old switch out for a new one. Set it to click (neutral) and installed with transmission in neutral. That took a couple of tries to get the gearshift lights to come back on.

Result was that it operated exactly like the old switch - no first gear, no matter if D4, D3, or 1st gear is selected. Info found, as well as diagnostic codes, all direct me to the Neutral Safety Switch.

Still have no first gear. How to get it to work is the question. First gear only works when the car is first started and the fluid is cold. Once warmed up it does not. No problems shifting between other gears once first is bypassed. Having to take off in second then shift to D3 and/or D4.

 

A lot of people have these problems with this transmission.

Where's the information on how to fix it? Been all over the web!! No straight and/or workable answers! Plenty of complaints, non relative posts, and idle banter, tho.
Honda refuses to be responsible. Shops too expensive.

What is causing this problem? What's the DIY fix?

 

Neutral Safety Switch does not look like it is the problem. As stated the new one did same thing, did not fix problem. Click stop is not audible. Can be felt when devices are rotated, but not heard.
The car runs fine EXCEPT it has no first gear after initial warm up. It will only pull the first few minutes while the fluid is cold.
Can overfilling the fluid do this? Which solenoid can cause this?
Tested and cleaned screen filters. They were not dirty to begin with.
Fluid is healthy red.

 

You can always try pulling all the solenoids and cleaning all the screens and filters.

 

Neutral Safety Switch does not look like it is the problem. Even though the error codes pointed to this part as the issue, replacing it with a new unit did not fix problem. Click stop is not audible. Can be felt when devices are rotated, but not heard. Car will not move until this click is set.
The car runs fine EXCEPT it has no first gear after initial warm up. It will only pull the first few minutes while the fluid is cold. Might this be the indicator of what the problem actually is? If it can pull with cold fluid, then the transmission itself is probably not bad.
Can overfilling the fluid do this?
Which solenoid(s) can cause this? Please post diagram showing all solenoids with their purposes. Only found one that had screens/filters. Tested and cleaned it even though it was not dirty. When it was put back in, the car drove normally on first startup but the D4 light blinked. I restarted the car and the D4 light went out and so did first gear.
Fluid is healthy red.
Need information for this model with this exact problem. Did extensive searching on web for information on this without success. No info on having first gear only, not working.

 

Did you find the solution? Mine is doing the exact same issue. Thanks