90 L5-2309cc 2.3L SOHC (NG) (1988)
8.
Disconnect the harness plug and check voltage between terminal 2 and ground.
a. With the ignition ON, 4.5 - 5.0vdc should be available.
b. Check voltage between terminals 1 and 2. 4.5 - 5.0vdc should be available.
9.
If current and voltage readings are within specification, replace the differential pressure regulator.
10.
If the current and voltage readings are not within specification;
a. Check for continuity between terminal 1 of the differential pressure regulator harness plug, and terminal 4 of the injection control unit plug.
b. Check for continuity between terminal 2 of the differential pressure regulator harness plug, and terminal 5 of the injection control unit plug.
11.
If resistance is more than 0.2 ohms, repair wiring as necessary.
12.
If resistance is 0.2 ohms or less, replace the control unit.