1. Check the transmission fluid level and condition. If the fluid shows signs of slippage or contains a burnt smell, recommend transmission overhaul or replacement.
2. Disconnect the PCM connection and turn the ignition switch to the Run position.
3. Connect a jumper wire to the Violet/Orange (VT/OG) wire at PCM pin 11 and tap it to ground. This should result in an audible "click" noise from Shift Solenoid B (SSB).
4. Connect a jumper wire to the Orange/Yellow (OG/YE) wire at PCM pin 6 and tap it to ground. This should result in an audible "click" noise from Shift Solenoid A (SSA) that is similar to the click noise produced by SSB.
5. If the SSA solenoid does not make the same audible click noise as does SSB, replace the SSA solenoid.
6. If the solenoids make a similar click noise when the circuits are tapped to ground, either the transmission valve body has an issue with a sticking valve, broken spring, etc, or, the 2-4 band has failed.