Here is the procedure to temporaily clear the codes so the CEL is off.

Black 2” box in front of battery
Remove lid
Turn key to run position
Press little button on box
Hold for 2-3 sec.
Code will flash back
Count flashes (26 for upshift delay valve)
Do again to confirm number of flashes
After final count wait 2 sec., and then hold for 8 sec.
Then turn key off and then immediately back to run,
(Do not start the engine)
Wait for 10 sec. for ECU to scan
Start engine after the 10 sec. wait
Keep engine running for at least 50 sec.