Aha! I think I may have a parts misidentification situation here. The ETR is under the dash by the accel pedal? Covered in insulating wool? Has a little schnozzle made of plastic sticking out one side (is something supposed to hook to that?) For some reason, I thought that the second switch or sensor on my R/D was the ETR. I have a black pot (pressure) and another one with red plastic that hooks to the other line on the R/D. What is that?

Already ahead of you on the fuse replacement vs check. I even scrubbed the fuse holders bright. That one has bit me before! (I'd love to have 5 minutes alone with the designer of those fuses.)

I'll wait for your confirmation of the ID of the ETR, even though a wire trace seems to confirm it. Then I'll short those and give it a shot. It's been a long day and I'm tired and I'm just paranoid enough not to start shorting random things under the dash.