Hi Phil. His 1986 240 B230F is LH 2.2 not LH 2.4 (1989-on). The ECTs for these two systems are different, but have a similar/same spec. This is noted in the 700/900 FAQ article I referenced.

The LH 2.2 ECT is Volvo p/n 1332396 (typically a blue connector) and is a single thermistor. One connector pin goes to chassis ground (black wire to the manifold) and the other to the ECU (pin 2, typically a blue wire for 240s and a grey wire for 700s). At the LH 2.2 ECU connector, the main ground for meter reference is pin 5 (to the fuel rail ground screw on the intake manifold).

The LH 2.4 ECT is Volvo p/n 1362645 (typically a black connector) and is a compound temp sensor with two thermistors, each on one of the two pins. The sensor case is the ground to the block. One thermocouple half is for the ECU (connector pin 13, typically a grey-white wire) and the other half is for the EZ-K ignition controller (pin 2, typically a red-black wire). At the LH 2.4 connector, the main ground for meter reference is pin 17 (to the fuel rail ground screw), while pin 5 is a separate chassis ground (for the O2 sensor shield).

Without doing more research to clarify and verify what's in the FAQ, it appears the resistance specs for various temperatures for the two different ECTs are the same, but the LH voltages in the circuit during operation may be different.

Basic testing can be done at the ECT if you can reach under the intake manifold and successfully get the connector off to get an alligator clip wire on the pins. When testing the LH 2.2 sensor you need to measure across the two pins, which may be a bit fiddly to do, so perhaps easier to do at the ECU connector. When testing the LH 2.4 sensor you measure each pin separately in reference to a chassis ground (like the fuel rail ground screw). If you were to measure the LH 2.4 sensor across the pins you would get the combined resistance, so double the spec.

For more accurate measurement comparing to the spec and allow for wiring/connector resistance you need to do it at the ECU connector, requiring side panel removal for access and removing the connector shell. For the LH 2.4 ECT you need to also test at the ignition controller connector, requiring under dash removal for access, which is a bit more of a nuisance.

If Art's following this maybe he can chime in here with any additional notes and specs.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now