Swapped the kickdown switch out and now really confused??

[Ascension]

Shifts up from 3 to 4 are absolutely normal and kickdown works as it should on 3-4.
1 and 2 however are "off". Mat it from a say 20 MPH roll car will hit 1st but will bounce off the limiter before shifting to 2nd. 2nd however at WOT will shift early at around 4200 so?
The ist to 2nd shift may be low fluid as I'm right at min hot but that low 2/3 shift does not make sense??
Hit it at speed( say 70 or so) and trip the kickdown switch 3rd will shift right at redline exactly where it should.
Now in normal driving everything seems to function as it should but at WOT and kickdown engaged is nutty. One question I do have is where should the trans upshift without the kickdown from 2 to 3 at high throttle? Will shift at 4200 or so now no matter if into kickdown or just under so??
Replaced the switch at the floorboard today but wonder if that relay which controls the gear hold could be the problem as it is unique to the 420. Time will tell if the cold hold issue returns as temps right now are well above when that issue surfaces.

 

[gsxr]

Get the fluid level to MAX when hot first.

With the kickdown solenoid unplugged, the WOT upshift from 2-3 should be in the 5500-6000rpm range. No clue why yours would upshift at 4200 from 2-3.

 

[Ascension]

Get the fluid level to MAX when hot first.

With the kickdown solenoid unplugged, the WOT upshift from 2-3 should be in the 5500-6000rpm range. No clue why yours would upshift at 4200 from 2-3.

Will do on the level. Yes that low upshift 2-3 did seem odd. made no sense it would shift just as it was really coming into the power band like that and was why I asked what WOT or at the least high throttle just below hitting kick down should be. Have the trans linkage set to react as soon as the throttle opens so should be holding longer. Will hold if shifted manually but not in drive. Don't know exactly what the shop I had do the cable and fluid change used so will find out ASAP and then get it full hot. The old kickdown switch appeared original to the car was easy to replace and not expensive so one more potential issue eliminated. Wonder if I should replace that relay k29/1. All this info is listed on pages 36 and 37 of the 400E-500E intro to service PDF. Also looking at the Y3/3 upshift delay shiftover valve that replaces the Y3 kickdown valve on the 400/420 trans.
Has to be some where there in the LH or in the valve body as there is nowhere else it could be. Whatever it is it's one hard gremlin to pin down I tell you that!

 

[gsxr]

Also looking at the Y3/3 upshift delay shiftover valve that replaces the Y3 kickdown valve on the 400/420 trans.
Has to be some where there in the LH or in the valve body as there is nowhere else it could be.

Y3/3 is a an electrically-acutated vacuum solenoid, located roughly above the brake bootser. There is nothing in the valve body, and the only difference in the LH is a signal to the relay K29/1 when cold.

The diagram in the manual you reference show the vacuum and electrical connections. All Y3/3 does is send a vac signal to the Bowden cable to increase shift RPM's, for a limited time, when cold.

 

[Ascension]

Y3/3 is a an electrically-acutated vacuum solenoid, located roughly above the brake bootser. There is nothing in the valve body, and the only difference in the LH is a signal to the relay K29/1 when cold.

The diagram in the manual you reference show the vacuum and electrical connections. All Y3/3 does is send a vac signal to the Bowden cable to increase shift RPM's, for a limited time, when cold.

I know about the Solenoid above the booster and thanks for clearing up for me on what Y3/3 is. One question would be which port should have vacuum on the new cable upper or lower? The original had only one and the early shift on 2/3 appeared only after the new cable went in. On K29 I'm suspicious as it connects through the kick-down circuit on a 420. Still have that delay/ skip from 1-3 and miss 2nd on a cold start but if above 60 degrees normally resolves after the first couple shifts.
What is causing that short 2-3 is as of now a mystery. It's as if suddenly cable movement is not affecting the shift on just that 2/3 shift so?? Kickdown is normal a say 60mph to 3rd and upshifts right at redline as it should ( don't try this anywhere but a wide open LONG straight as with this gear---). car pulls strong and smooth now + have normal low speed down shift to 1st just not second with out tripping the kickdown above say 30mph will hit 3rd not second. Weird stuff and in the end may have to just pull and build this unit to fix this.
Spend my younger days building and doing R&R / trouble shooting in a Trans shop on mostly US rear drive stuff back in the late 70's-mid 80's but this one has me just stumped .