How the hell?
12-14-2014, 04:20 PM
#1
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Car: 89 Camaro RS running MS2X
Engine: .48/.60AR T3/T4 2.8L V6
Transmission: Rebuilt 700R4 2500 stall
Axle/Gears: Next to break...
So my ground trigger wire on my rad fan relay, is now a 12v switched wire, and the 12v switched wire, is now a ground wire.
It has been wired the same way for 3+ years, and has worked flawlessly. Rad fan was on when I pulled in the driveway last night so I know it was working as it should. The ONLY thing I did was splice a trans fan relay ground trigger wire into the ground trigger for the rad fan. Soon as I plug the ground wire back into the rad fan relay with the key on, the trans fan comes on without the coolant fan. This is with the ground trigger wire grounded. To make the rad fan come on, I have to apply 12v to the relay ground wire(with the ground disconnected obviously).
It has been wired the same way for 3+ years, and has worked flawlessly. Rad fan was on when I pulled in the driveway last night so I know it was working as it should. The ONLY thing I did was splice a trans fan relay ground trigger wire into the ground trigger for the rad fan. Soon as I plug the ground wire back into the rad fan relay with the key on, the trans fan comes on without the coolant fan. This is with the ground trigger wire grounded. To make the rad fan come on, I have to apply 12v to the relay ground wire(with the ground disconnected obviously).
12-14-2014, 05:45 PM
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Car: 89 Camaro RS running MS2X
Engine: .48/.60AR T3/T4 2.8L V6
Transmission: Rebuilt 700R4 2500 stall
Axle/Gears: Next to break...
Let me clarify. My ground trigger now requires 12 volts instead of ground to trigger the relay. Wired as stock. The 12v wire is now a ground. I changed NOTHING.
AKA tan/white is now ground and green/white needs 12v to spin the fan. Green/white is the ground input and has been that way since the car came out of the factory. Tan/white was also switched 12v from the factory. Now they are opposite without touching anything.
I say nothing as adding the extra ground trigger has nothing to do with the issue as I removed it and it didnt change.
Last edited by willexoIX; 12-14-2014 at 05:49 PM.
12-15-2014, 01:55 AM
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Car: 1989 Iroc-Z Camaro
Engine: TBI,5.0
Transmission: Automatic 700R4
Axle/Gears: Eaton Posi,3.42,LPW Ultimate Cover
Re: How the hell?
Don't yell at me, I just have a question.
Would this be considered a ground triggered relay ?
Its the first I've heard the term used here.
A simple yes or no will do.
I have two of these wired in controlling two different fans.
They are totally independent circuits of each other including the stock wiring.
Would this be considered a ground triggered relay ?
Its the first I've heard the term used here.
A simple yes or no will do.
I have two of these wired in controlling two different fans.
They are totally independent circuits of each other including the stock wiring.
Last edited by Ron U.S.M.C.; 12-15-2014 at 07:35 PM.
12-15-2014, 09:57 AM
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Car: 89 Camaro RS running MS2X
Engine: .48/.60AR T3/T4 2.8L V6
Transmission: Rebuilt 700R4 2500 stall
Axle/Gears: Next to break...
A 12v triggered relay would be the stock fuel pump relay in our cars.
I want to say in my case that the 12v is shorted to ground, but no blown fuses, no hot wires, nothing. But as I said if I put 12v on whats been a ground on the fan relay since the car was built, the coolant fan comes on. If I put ground to it, nothing.
12-15-2014, 03:20 PM
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Car: 1989 Iroc-Z Camaro
Engine: TBI,5.0
Transmission: Automatic 700R4
Axle/Gears: Eaton Posi,3.42,LPW Ultimate Cover
Re: How the hell?
I wish I could help you with this but you seem to know more about it then I do.
The reason I wanted to know if that is called a ground triggered relay is because of the two main circuits I have been using for a inexpensive temp. controlled, adjustable fan switch able to handle even the highest amp fans.
The reason I wanted to know if that is called a ground triggered relay is because of the two main circuits I have been using for a inexpensive temp. controlled, adjustable fan switch able to handle even the highest amp fans.
Last edited by Ron U.S.M.C.; 12-15-2014 at 08:08 PM.
12-15-2014, 05:09 PM
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Car: 89 Camaro RS running MS2X
Engine: .48/.60AR T3/T4 2.8L V6
Transmission: Rebuilt 700R4 2500 stall
Axle/Gears: Next to break...
I wish I could help you with this but you seem to know more about it then I do.
The reason I wanted to know if that is called a ground triggered relay is because of the two main circuits I have designed for a inexpensive temp. controlled, adjustable fan switch able to handle even the highest amp fans.
The reason I wanted to know if that is called a ground triggered relay is because of the two main circuits I have designed for a inexpensive temp. controlled, adjustable fan switch able to handle even the highest amp fans.
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12-15-2014, 05:48 PM
#8
Re: How the hell?
Here is one possible reason ;Say , for instance your #85 terminal , which is fed 12V from the ign switch in Ron's drawing was in a circuit that was also feeding something else , like a light bulb , perhaps . Say you got an open circuit in that 12V feed , an open that still allowed the bulb and relay to be electrically connected , but not being fed their power due to the open circuit being right after the ign switch . If you then put 12V power to the #86 terminal , it will flow through the relay's coil , through the light bulb to ground , and complete the circuit to end up energizing the relay in the way you describe .
I used Ron's nice drawing as a starting point , and drew a circuit explaining my thought on this . I'm no artist but I hope it shows clearly what I'm saying ?
12-15-2014, 05:53 PM
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Car: 89 Camaro RS running MS2X
Engine: .48/.60AR T3/T4 2.8L V6
Transmission: Rebuilt 700R4 2500 stall
Axle/Gears: Next to break...
Here is one possible reason ;Say , for instance your #85 terminal , which is fed 12V from the ign switch in Ron's drawing was in a circuit that was also feeding something else , like a light bulb , perhaps . Say you got an open circuit in that 12V feed , an open that still allowed the bulb and relay to be electrically connected , but not being fed their power due to the open circuit being right after the ign switch . If you then put 12V power to the #86 terminal , it will flow through the relay's coil , through the light bulb to ground , and complete the circuit to end up energizing the relay in the way you describe .
I used Ron's nice drawing as a starting point , and drew a circuit explaining my thought on this . I'm no artist but I hope it shows clearly what I'm saying ?
12-15-2014, 07:48 PM
#10
Re: How the hell?
Yes , it's not an open circuit to ground , because it's backfeeding to ground through some other device on the same circuit . But it IS an open circuit to +12V , and that's why you need to apply +12v to what is it's ground side , in order to energize the relay . The only way the wire that had been switched +12V could have somehow been connected to ground would be for it to have lost it's +12V feed and been in Parallel with another device (that is now acting as the path to ground your seeing on that side of the circuit).....
12-16-2014, 10:38 AM
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Car: 89 Camaro RS running MS2X
Engine: .48/.60AR T3/T4 2.8L V6
Transmission: Rebuilt 700R4 2500 stall
Axle/Gears: Next to break...
Yes , it's not an open circuit to ground , because it's backfeeding to ground through some other device on the same circuit . But it IS an open circuit to +12V , and that's why you need to apply +12v to what is it's ground side , in order to energize the relay . The only way the wire that had been switched +12V could have somehow been connected to ground would be for it to have lost it's +12V feed and been in Parallel with another device (that is now acting as the path to ground your seeing on that side of the circuit).....The harness was redone when I installed the Megasquirt. The fan relay was the only thing left on that wire when I buttoned everything up. I can confirm that cause I almost cut the fan relay out instead of the MAF relay.
Last edited by willexoIX; 12-16-2014 at 11:01 AM.
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