My 70 Nova project (Formerly looking at this mustang)

[Gaffer]

The computer supplies a ground, will this work to #86? I thought 86 was a switch on wire requiring

I'm not sure I understand the question but think of it this way. 85 and 86 only energize the coil inside of the relay. This in turn throws the switch for whatever it is you want to switch. The coil does not care if 85 is power or if 86 is power, but whichever pole you choose to 12V+, the other pole has to be 12V-, and one of those will always be connected to the input source - in your case, the computer. Because the computer throws a ground (12V-), the other pole 85 or 86 your choice, needs to be constant 12V+. Now, when the computer throws the ground to activate the fan, the coil is energized because it has 12V+ on the coil's other pole (85 or 86). As soon as this happens, the switching part of the relay comes into action. Look at the diagram on the relay for poles 30, 87, 87a. It shows you that when the relay is not energized, power and ground on 85 and 86, 30 is connected to 87, but when you energize the relay, it flips the switch and connects 30 to 87a, and nothing is on 87. This is why you will not be using 87.

By connecting it this way, The relay will always have 12V going to it (85), but it's not doing anything until the ground is applied to 86 (from the computer). When this happens, the relay will connect 30 to 87a. Since your fan will have battery 12V+, it will need a ground to turn it on. It gets the ground from 87a.

If you have some alligator test leads or spare wire, you can test it. Put 12V+ on 85 and then touch a ground wire to 86. You'll hear the relay click, and then click again when you remove either power or the ground. Since nothing is connected to 30, there is nothing on the switch. I can draw you a diagram if it makes it easier.

 

[Gaffer]

Working on wiring my my radiator cooling fan and although I've done them many tiems before this is different. Usually you provide a ground, a fused hot wire, and the turn on wire controlled by something or other.

With the computer controlling the fan it provides a ground to the fan. Somehow I don't think the computer can handle a 30 amp 3000 CFM fan without a relay.

So I bought a heavy duly waterproof relay I'll mount right under the fan so I can kind of hide it but still be accessible.

I've never been an electronics wiz and I freely admit that. So my plan is to run a ground wire to the fan motor. Then run a fused hot wire to the relay for both the power and the turn on pole. It will be fused hot all the time. Then run a wire to the relay ground terminal and have the computer ground out the relay to turn the fan on. That way the computer doesn't see the heavy switching load of grounding the fan out as the fan is grounded separately.

I realize that relays as far as I know aren't made to be hooked up this way, but will it work?

I've attached pic of the relay. I "think" I need to run pin 86 and 30 to fused power, then run #85 to the computer ground. 87 and 87A won't be used.

So am I all wet on this? Won't be the first time if I am.


View attachment 371920View attachment 371921

Looking at your diagram, I steered you wrong. At rest, 30 is connected to 87a, and switches to 87 when the coil is energized. I'm used to Bosch relays, and either I misremembered them because it's been years since I've installed one, but the rest of my advice should be solid. Based on your relay, 87a will not be used, and 87 will go to your fan's ground wire. Sorry about that.

 

[Gaffer]

To make it more confusing, or help you understand the relay better, you could ground your fan, and put 12V+ on pole 30 and then run 87 to your fan’s power wire. In this scenario, the coil, 85 & 86, stays wires the same as I’ve described above. When the computer triggers the coil, pin 30 sends 12V+ to turn in your fan. This way probably makes more sense for ease of wiring. Ground wires should be kept short.

 

[alloy]

So, in other words, your question is, will the computer successfully provide the fan ground (and not throw a code) when it is grounding a relay coil rather than grounding an actual fan motor.

Is that what you're concerned about?

I don't know the answer to that question. Hopefully Gaffer (or other) can answer it.

Yes that's what I was wondering. I know if I don't have the correct resistance check engine light lamp the computer throws a code for that. It has a code for everything it seems. I think its not easy for the programmer to figure out what things they can delete out of the computer to check for and still maintain enough function to run the engine.

Honestly I'm more confused now that when I posted the question. I need to look at what's been said and go from there.

 

[alloy]

My bank balance is much smaller today.

 

[alloy]

I'm a little further along than in my last video. Pretty much every thing for the engine is in place. Cooling system, intake, no air filter at the moment, had to pull it off, spilled coolant on it while filling the radiator and need let it dry out.

Have 40psi of oil pressure at idle, SES light works with the resistor (thanks for the help on that) and no check engine light on.. I didn't take a volt meter but the volt gauge shows 14 volts so looks like it's charging. But no tach, hooked up and I'll have to see what's up with it. Fuel gauge shows 1/4 tank.

Started at high ldle and went to normal idle pretty quickly. I still have it in my shop on the lift and ran it until my eyes were burning and shut it off. The drive by wire throttle pedal works.

Lots more to do. Finish the inside wiring, get the tach working, and figure out why my left dash turn indicator is on. Get the new carpet in, shifter, need to get a steering wheel. Just missed a nice grant one that was on FB.

Getting closer.

 

[alloy]

Found this on tach problems. I've never had to splice in 12v with the tach feed wire before. I ordered some resistors, they will be here next week.

It is an autometer tach.

 

[alloy]

Well I tried everything I could find to get the tach working to no avail. So broke down and bought the autometer tach module and harness. Expensive, but it works. Hated to spend that much on a $20 electric box.

Had the engine running and couldn't get it into gear. I could see through the inspection plate the hydraulic throw out bearing was moving forward and looked like it was releasing the clutch. So tried again and started it in gear and put the clutch in and I could see the speedometer stopped. So shut it off and thought about it. My thinking was with the car is gear and the drag of the drivetrain the clutch released, but wouldn't go into gear when I pushed the clutch in. I remember the input shaft fit pretty tightly in the pilot bearing and all I could think of was there was enough drag from the pilot bearing to be too much for the syncros to overcome to stop the clutch and let it go into gear. So I started it in gear, held the clutch in for about 3 minutes with the rear wheels not turning and low and behold now it goes into gear. I was dreading having to pull the trans back out. Glad I slept on it and figured out what was going on.

Now I have a problem with the hydro boost. Pedal goes down and doesn't come back up. Double checked the pressure and return lines and they are in the correct places. I have about .01 end play on both the pedal pushrod and the master cylinder push rod out of the hydro boost. Read everything I could find on this. Most of them say the lines are backwards, but it's pretty easy to see they are not.

Anyone here worked with hydro boost before?

 

[GoceKU]

If memory serves good after installing new hydroboost it needs bleeding, to fill the rezerve reservoir. Had an transit van do the same thing, i don't remember but i thing i keep pumping the pedal with the engine off then on and sucked fluid from the power steering and got the brake pedal back.

 

[alloy]

I've pumped it many times bleeding the brakes and trying to figure it out. Unfortunately didn't help. It's good to know someone experienced the same problem.

One thing I did realize is I don't have a brake pedal return spring. I've ordered one to give it a try. I've tried to find out if an astro van that the hydro came off of has a return spring or not. If it doesn't really need the spring it really won't hurt putting one on.

Probably be a week or so before the spring comes in. I really hate waiting for parts. Unfortunately gone are the days going to the speed shop and getting parts.