Thread: Test a Relay
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john70t john70t is online now
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Join Date: Aug 2001
Location: midwest
Posts: 40,493
Four-Terminal relays are very easy:
1). There are 2 bigger pins which is the load-circuit.
-The "heavy juice" goes through this just like a normal wire.
-This circuit is usually "open" until the control side is energized.

Use the OHM function of a DVOM.
The OHM function is usually safe to use on most big electronics. It sends milliamps across the terminals to find what level of continuity exists.
(Do not use this on live circuits, or you'll blow the meter!!!)

2). There are 2 smaller pins which is the control-circuit.
-Voltage is sent through this by the electronics or manual switches in the dash/pedals.
-Using the OHM function, there should be some continuity.

Basically a relay is a mechanical switch.
When a small amount of juice is sent through the control-side coils in the relay, it pulls a mechanical switch of the load-side closed.
Heavy juice then flows through the relay to operate motors and whatnot.
Old 10-20-2012, 12:51 PM
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