Ground Circuit Check
WARNING: This page is about a different car, the 1993 Volvo 940. However, it is still accessible from the selected car via links, so may be relevant.
Connect ohmmeter between ground and fuel injection ECU terminals No. 5, 17, 19 and 29 (Jetronic 2.4 fuel system) or terminals No. 5, 17 and 19 (Regina fuel system). In each case, reading should be zero ohms. Wires are grounded to intake manifold.