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...in that white case:
Main relay powers the ECU, AMM, Injectors, eyc. [about everything but the pumps]
Fuel relay powers the pumps.
Key ON II — Both relays energize
• Main relay stays energized/on.........
• Fuel relay drops out after 2 or 3 seconds
>>both relay "CLICK(s)" feel like one
>>[drop-out can be felt, but some '89s may not energize Fuel relay at Key On]
Key On III — Cranking now
• Main relay still energized....
• Fuel relay (re)energizes, but ONLY if ECU gets "OK signal"* from Ignition CU
>>[single relay "CLICK"]
• Fuel relay stays energized under ECU control (as long as Ignition allows)
* Ignition "OK signal" is a string of timing pulses derived from Crank Position Sensor pulses received at Ignition CU.
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