you dont need a tool,
the solenoids are basic on/off switches, make a small LED panel on cardboard and tap into the wires from the connector or the ECU and see when the shifts are being commanded, The ECU sends 12V positive to the wires. The solenoids are 1 amp units (meaning 13 ohms) - so dont use a huge bulb that can blow the ECU, LED are best.
this is the sequence - first column is sol 1 and second is sol 2
on - off = gear 1
on - on = gear 2
off - on = gear 3
off - off = gear 4 (aka overdrive)
SL is lockup and is applied after overdrive is achieved, dont worry about that one.