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About the System relay... 700 1989

uid 18083's pic
posted by  lucid on  Thu Sep 26 06:54 CST 2013
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last visit: Fri Oct 24 12:31 CST 2014
[RELATED]

Sorry Eric,

I blew it. I should have said: "There are 2 FI relays in that white case behind the ashtray"

The picture below shows them with the cover off. The System relay is on the left and the Pump relay on the right, rigged for testing to be always "On" by the piece of hose holding the armature in the energized position.

... The System relay is "picked" when the ECU senses the key is position II. The System relay Coil voltage is hard wired from Fuse 1 (at least in my '93 Regina FI). When picked, the System relay then powers:
• Fuel ECU (operating voltage vs "stand-by" power),
• Fuel (pump) relay coil + side (ECU will control coil ground)
• Idle Air Control valve (IAC) (ECU will control coil ground)
• Radio Suppression Relay (RSR), which powers + side of the Injectors (ground side controlled by the ECU)

The Pump relay should also be picked at KPII (for 1 or 2 seconds) for the so-called "Prime Cycle". This is ECU-controlled, but the details of this short cycle is not described in the service manual.

Are you getting a relay click at KPII? Put the relay in with the cover off to hear better. If the System relay clicks, try rigging the Pump armature as shown. This still leaves the relay under ECU control, and is thus safe for testing purposes IMO.



--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.






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