PO 741 Fault Code solutions/options

Question

I have a 1999 Cadillace Eldorado with ony 76K miles on it and it has a check engine/service light that comes on and when I use my OBDCOM device it relfects PO741 torque converter circuit fault. My question is from the forum discussions they say to change transmission oil and filter as the first option and less costly. Is there anyway to verify it is dirty or contaminated oil vs checking the Trans. converter circuit without taking the trans. cover off the side the transaxle. I have been a auto mechanic for a long time and maintain my own cars. I also know quite a bit about electronics on cars and aircraft so is there a means to test/check the circuit via multimeter measurements.

I have no plans to take this car to Cadillac or any other auto service as I believe in DIY

Appreciate any suggestions/comments.

JK