[rivverat]

1996 Ford Windstar 3.8 L 92K miles one owner.
P1538 IMRC stuck open, (Bank 2). That is the only code I get, no others. Both IMRC’s SEEM to be operating properly. The van runs fine, no roughness and does not hesitate or die.

I have verified:
-there are no holes in the actuator diaphragms, that is they both hold vacuum
-the butterfly rods move freely and smooth as silk
-I replaced the little plastic linkage retainers
-operated both IMRC’s manually and by removing the vacuum hoses
-ran engine up over 2950 rpms and verified both actuator do in fact close and then open after rpms drop.
-cleared the code (and CEL) by removing the negative battery cable.

The light came back on after driving about 20 minutes. I pulled over and raised the hood and checked both IMRC’s again, they were open when idling, closed when I pulled the vacuum line which is correct.
So… I’m thinking that the IMRC SENSOR may be bad. It is integral with the IMRC. The wires that plug into them are a 3-wire plug. I have tried to test them with continuity and ohms but really do not know the proper procedure.
The readings I do get seem to be consistent between the 2 IMRC’s though.

Does anyone know if there is a procedure to check the sensors?

Does anyone know if I should be looking elsewhere?