K so I have a bagged 91 toyota running dual 480c's. The relays keep getting stuck in the on position. I've checked all the wiring and redid the grounds. Anyone know what may be causeing this?? I've gone through 5 relays trying to figure this out.

 

When they stay on, is the control side hot or is the control signal shut off? If the control signal is gone, it's probably too much current and the high current side for the relays you're using fusing the contacts?

 

The pressure switch signal should trigger the relays off ,check it!!

 

Its not the pressure switch. And the control signal is shut off mewning the switch inside the truck. And they still run I took one of the relays apart and you can see where the little arm thing was welded to the compressor prong part

 

i've never had this issue, but i user starter style relays that are made for huge loads of current.

 

I'm using viair 40 amp 4 prong relays

 

Well I think I figured it out. Got my hands on a voltage meter today and I'm reading 20 volts at the relay on all connections. So should be a bad voltage regulator inside the alternator.the alternator at az is 60 amp. Is there a higher amp direct swap I should do while I'm at it?

 

I went to a GM 3-wire,see my post on this subject!
100 amps @ idle /150 a speed!
Also run a 1500amp hour Odyssey!

 

Part of the problem anyway. Voltage won't weld the contacts in the relay, amperage does that.

 

K new alternator is in and its still doing it. I searched every local stre for a multimeter that would test amperage and the best I could find is 10 amps. Anyone know of what it could be or where I can get something that will test more then 10 amps

 

You say the control signal is shut off !!
The control signal comes from a pressure switch ,no signal a bad pressure switch. All pressure switches come on & off @ preset pressures read @ the tank. Some are adjustable!
Check the tank pressure with a mounted gauge ( you can get one from 0-300 psi ) @ OSH hardware's $10

A relay is just a electrical magnetic switch!

Check all the feeds ,power always @ one pin , switched power @ another 9igntion on or other) ,ground @ one , & the power out that should be the pump feed @ another pin. Always run a in line fuse as close the the power supply has possible!!

I run two pumps ,two relays & a Auto Pilot controller that as the pressure switch built into it. Receives a on of signal from a pressure sensor @ the tanks! The power supply is a separate distribution block inside the cab , also run one for the grounds,these feed amps & pumps only!!

 

Yeah the signal from the switch and from the pressure switch are both shut off and it still runs. The compressors kick off when the pressure switch shuts off then they stuter a little bit then kick back on until I unplug the battery. I'm using an air zenith adjustable pressure switch. Set at 135-175

 

Change the pressure switch as I stated before!
Just use a set one ( less money ) & if a fix you can order another of what you use!

 

So to go further into it. My wires to the relay is power with a 70amp fozgate fuse. Ground is going to the pressure switch then out to the battery. Then another out to the compressor and the last goes to the toggle switch inside of the truck. Its kind of back asswards wiring but it works. So I read on the az forums that if I disconnected the air pressure switch wiring and there for removing the ground to the relay that the compressor will shut off if it is a faulty air pressure switch. So I did that and the comp still runs.

 

Its those cheap ass relays bro. I had same problem. I run a fused 150A relay now with no problems. Too bad I didnt see this post earlier couldve saved you an alternator. I dunno why they give people the supposed "40a" relays with the compressors. As soon as I saw mine I threw 'em in the trash. I was running 2 bosch 75a relays for awhile, but after they got old they started sticking on too.

 

At the shop we always run a heavy duty 80 Amp relay, and have never had a problem. We never run the cheap relays that come with the compressors. They just can't handle the load the compressors draw.

 

How many times do you need to be told to get new relays? better relays. Yes it's gonna cost a bit.

10a is the most you'll find in a consumer meter. Any more than that and you need a clamp-on type ammeter. When looking, make sure it reads DC, many only do AC.

UnderConstruction93: His alternator was overcharging at 17+V (probably burned out the voltage regulator with the compressors) so he needed the alternator anyway.

 

k so last weekend, me and my brother rewired it from the switch to the pressure switch then to the relays how it is supposed to be. Then grounded it from the relays. Everyone is telling me to NOT use the ford starter relays because they are only designed for short use. So i just orderd 2 air zenith 80 amp relays. they shouldn't blow considering my alternator is only pushing 60 amps. And yes i was reading 18-20volts before i swapped the alternator, but i have a lifetime warranty so no worries about that hopefully this fixes it. ty guys.

 

I could've got you 1 relay cheaper than those 2 that would've never given you a prob. But yea, that's what you need...