Relay 109 is your main ecu power relay.
Here are the Relay 109 Circuits: (stolen from another forum)
Relay 109 and associated Circuits Located at Position 12 in the upper relay panel.
Relay 109 is identified as J317, Power Supply from Terminal B+ (hot at all times) with power activation from the ECU when the key is in the ON position
Power Circuit to Relay 109
1. Power (6.0 size red wire) comes from Fuse S176 (110amps) at the plastic box on battery to Threaded Connection 500 at the relay plate -1- (30).
2. From the Relay Plate, at Connection 501 the power (6.0 size red wire) goes to Splice A98
3. From Splice A98, the power (4.0 size red wire) goes to Terminal 2/30 of Relay 109
Relay Circuit (activated when the Ignition is turned on)
1. Connection 9/85 goes to Blue Connector T10h/8 on to ECU at T121/18
Power Circuit away from Relay 109
1. Power away from Relay 109 is via 4.0 Blue Wire to Splice A71
2. At Splice A71, there are three circuit branches (A, B, & C, my terminology)
Circuit - A. 1.5 Wire goes to Fuse 34 (10 amp)
Circuit - B. 4.0 Wire goes to Fuse 32 (30 amp)
Circuit - C. 1.5 Wire goes to Fuse 43 (10 amp)
Circuit A (with two branches) ........ engine operation functions
From Fuse 34 goes to Splice 100, first branch provides power to: MAF (G70), Wastegate Bypass Regulator Valve (N75), EGR Vacuum Solenoid Valve (N18) and Change-over Valve for intake manifold flap (N239) Note: tied to this same circuit, is another circuit that comes from a 1.0 size wire from connection 6/87 of the GP relay. The second branch , Splice 100, goes to the 14 Pin Connector at T14a/6 on to Cold Start Injector (N108)
Circuit B (with two branches)
From Fuse 32 goes to Splice B168, first branch (4.0 wire) goes to Brown Connector point T6/4 on to splice D74 and provides power to: ECU at T121/1 and T121/2 via the two branches at Splice D74. The second branch goes to the 10 pin connector at the Injection Pump (G149), connection T10f/5
Circuit C (with three branches)
From Fuse 43 goes to Splice A155 , the first branch goes to Clutch Vacuum Vent Switch (F36). The second branch (page 10) goes to Brown Connector at T6/6 with double wire of which one goes to a 53 Relay J359 for Low Heat Coolant GP and the other goes to the Positive Crankcase Ventilation Heating Element (N79). The third branch goes to the Brake Vacuum Vent Valve Switch (F47)
