Control Pressure Regulator

Unplug connector at control pressure regulator. With voltmeter, check for 11.5 volts at wiring harness connector. On 1975-77 models, disconnect air sensor connector and positive wire at alternator (Volvo only).
On 1978-79 Volvo, connect Test Relay (5170) to ignition coil. On 1978-79 Saab, connect jumper wires to fuel pump circuit and remove positive wire at alternator.
On all models, connect ohmmeter between positive terminal on control pressure regulator and ground. If ohmmeter reads infinity, replace control pressure regulator.