Why won't my relay work?

[1QWIK6]

I have a Bosch 4 pin Relay.

30- ground
85-86 coil
87 - normally open

(This relay is going to a LT1 emission air pump - being used for a vacuum pump)

I connected the 2 wires from my emissions pump to 85 & 86. Ran a ground to 30 and B+ to 87. Nothing.

What am I doing wrong?

 

[Daniel Jost]

shouldn't there be a positive and ground ran to the coil, maybe im just not thinking right without having it in my hand to see?
,Dan

 

[David65]

I have a Bosch 4 pin Relay.

30- ground
85-86 coil
87 - normally open

(This relay is going to a LT1 emission air pump - being used for a vacuum pump)

I connected the 2 wires from my emissions pump to 85 & 86. Ran a ground to 30 and B+ to 87. Nothing.

What am I doing wrong?

It's a good thing it did nothing. If the relay had turned on it would've shorted B+ to ground. 30 is the common, which gets connected to 87 when 12V is applied to the coil, 35 & 36. I assume you want to switch the ground to the pump since you indicate 30 is ground? If this is the case, connect 30 to ground as it was. Connect 87 to the negative side of the pump, and the positive side of the pump to B+. (might want a fuse in there?) Connect either 85 or 86 to ground, then the other to some 12V source to turn the relay on. The polarity going to 85 & 86 shouldn't matter as long as the relay doesn't have a diode built into it. If it's one of the cheap ones from RS or Autozone etc, it probably doesn't.

Some info on relays is here: Relays, Single Pole Double Throw (SPDT), Automotive Relays

David

 

[1QWIK6]

It's a good thing it did nothing. If the relay had turned on it would've shorted B+ to ground. 30 is the common, which gets connected to 87 when 12V is applied to the coil, 35 & 36. I assume you want to switch the ground to the pump since you indicate 30 is ground? If this is the case, connect 30 to ground as it was. Connect 87 to the negative side of the pump, and the positive side of the pump to B+. (might want a fuse in there?) Connect either 85 or 86 to ground, then the other to some 12V source to turn the relay on. The polarity going to 85 & 86 shouldn't matter as long as the relay doesn't have a diode built into it. If it's one of the cheap ones from RS or Autozone etc, it probably doesn't.

Some info on relays is here: Relays, Single Pole Double Throw (SPDT), Automotive Relays

David

Thanks david

I hear a "click", but nothing happened. Could this have a diode in it? I reversed some wires, all I get is "click".