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Home » Public Forums » GMCnet » Relay races ((*%&*^)
Relay races [message #258611] Tue, 12 August 2014 16:28 Go to previous message
kerry pinkerton is currently offline  kerry pinkerton   United States
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma:
Senior Member
Ok, so everyone needs to know their limitations and mine is electronics. Poor Ken Henderson has been very patient but probably rues the day he became my friend. Embarassed Shocked Laughing

I'm going to dual electric fuel pumps and have been talking to Ken about how to wire everything up. Finally thought I understood everything and started to wire things up. Installed the low oil pressure switch and the relay to provide power when the motor is being cranked OR running with oil pressure...otherwise no power and the pumps shut off. This first relay is called the Pump Power Relay.

That relay output feeds another relay is double pole and provides power to one pump or the other based on the 12V signal from the tank selector switch. This is called the Pump Selector Relay and is a 5 pin relay. Ok, I got this. Before I wire everything up permanent, I wire up the power relay and verify it works. Yep, as soon as the engine starts cranking I got voltage. So let's check the other relay...humm no power on either of the two output terminals. WTH! (85 to ground 12V from Battery to 30) Should have 12V on one of the 87 output terminals. Nothing Double check. Triple check. No output voltage on either of the output terminals (87 and 87A)*(&%%^)

Quadruple check. DAmn. Ok, let's apply 12V to the trigger connection to see if that side of the coil works. Relay does not click. Still nothing. **&^%%

So another call to Ken and we agree the NEW relay is defunct. At least I'm not nuts.

Picked up another relay when I was in town today. Wired it up. Nothing on either of the 87s. WHAT! So I apply the trigger voltage to 86 and hear the relay click. Check for volts on the 87 terminals. Yep got it on 87A.. 87B should be cold. WHAT! It's got 12V too. That won't work! It has to switch. Pull the trigger voltage and both 87's loose power.

Call Ken back and walk him through what I did and we agree this SECOND NEW RELAY (one from my son at Advance and the other from OReillys)is also bad. What are the odds of that???

Called my neighbor buddy Beau and ask if he happens to have a 5 pin relay and he says he does and will bring it over. Works fine and as expected. Wasted the better part of a day futzing with bad new components.

The good news is that I now have a very sound understanding of how relays should and should not behave and how to wire them up. And of course it's now raining and 300% humidity and 95 degrees so I'm working on another project the rest of the day. ))#$^%!

Kerry Pinkerton - North Alabama Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L

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