Four over 3 years my Renegade dual fan setup worked flawlessly. Both fans were setup to come on at once at full speed. Wanting to reduce the noise of the fans, I rewired them according to the diagram below that others have used and were happy with. I have carefully checked and rechecked my wiring with the diagram. Here is what happens.

If you trigger Pin42 C1 (low speed-both fans running in series), you can hear the relays but absolutely nothing happens. No fans start, and no wiring melts.

Triggering Pin33 C2 (high speed-both fans at full speed in parallel), Fan1 starts and all the wires connected to 87a on relay 3, 87 on relay 2 instantly start melting).

I have a 6 gauge wire running from the battery to the fans. All wiring used to connect the relays and fans was 14 gauge. The wires coming out of the fans is 14 gauge. A direct ground is bolted to the shell in the front trunk.

I am at a loss, at what is going on. Obviously, I must have something wired incorrectly but like I said, the connections are exactly as the diagram shows.
Any help would be appreciated
Click to view attachment
Click to view attachment
Click to view attachment
Click to view attachment
Click to view attachment

Is 87a normally closed on the relay?

Here's pic that I think explains your question. I have a hard time fully understanding how the above diagram works.

better yet, provide part numbers for all 3 relays. Looks like different version relays exist, ones with normally open pin 87a and normally closed

You said if you trigger......that means you ground c-1 & c-2, right?

Edit: as long as the relays are large enough it shouldn't matter too much which ones he uses as long as relay #3 is a 5 pin, right? Check your wiring again.

Yes, ground the sensor leads to ground.

I'll see if I can read the part numbers. R1 and R2 are the original Bosch relays that came with my Renegade kit. The middle relay (R3) was bought at my FLAPS, not Bosch, but 30 A with all 5 correct numbered pins?

Below are the two types of relays.

When you trigger C2, the purple wire from relay three, goes to ground, at the same time the same purple wire on relay 2 goes to positive, thats whats causing the short. As for getting it to do what you want I'm not sure. But that should help with the shorting problem.
edit: Wait a second, I'm second guessing myself? I have to draw this out, my idea above is right out of er! disregard.
Jon

Here's the schematic of the circuit.

Assuming the C1 and C2 switches close to ground.

There are a lot of assumptions going on for this relay schematic to work.

Assuming all of the relays are NC on 87a and NO on 87:

First, are you sure that both relay 2 and 3 are able to operate while being grounded through a single pin Pin33/C2? (are the relays wired in series or parallel to pin33). Is pin33 a computer or another relay/switch? If it is a computer/pcb, it may not pass enough current to trigger both relays.

I would disconnect the fan power supply "battery hot", grab a DVM and ensure that the correct relays are operating when triggered by C1 or C2. Much easier/safer than burning up wires.

Do C1 and C2 both ground for high speed or only C2?

Once you understand how your relays are acting it should be easy to figure out.

If everything is operating as expected, the schematic should work. Instantaneous melting of wires pretty much means they are grounding out, so either the relays aren't operating as expected and are causing a ground loop or you've wired it incorrectly.

Also check to make sure that the fans will turn on at half speed when connected in series. Essentially you are running each fan on 6 volts. That may not be enough, this may explain why you have no fans running when on low speed.

I can check tomorrow to see if the fans can run in series at 1/2 speed by bypassing the relays etc.

I will not be using an ECU to trigger C1 and C2, I will be using two separate 3/8 screw in temp sensors into the radiator (180, 200)

Sounds like I was naïve in thinking if I just followed the diagram exactly using 5 pin relays with the correct pins all would work. Others have said the diagram works well for them...I'm not trying to re-create.

Does the pictures of the pinouts on the relays shown look to be correct? I can check tomorrow with a meter.

you really should test the setup and circuit with out the fans in the loop and use a volt ohm meter [vom] or aka digital volt meter [dvm].

test each stage of the circuit as it is put together.

and where are the fuses!!!!!!!!!!!!!!!

you should at least have 1 30-40 amp fuse or breaker on the 12 batt supply wire!!!!!!

Schematic looks fine. From what I'm reading, you ground Pin 42 C1 for low. This runs the 2 fans in series for a lower speed. When you ground these 2 pins (Pin 42C1 and Pin 33 C2) together, this isolates both fans (parallel) for a high speed.

Edit: Consider replacing the relays to something more heavy duty. I used these heavy duty, high inrush current relays for my friends car recently. http://www.mcmaster.com/#automotive-relays/=qki8kf I would choose the 50 amp 4 pin ones for relay 1 and 2 and the 35 amp 5 pin relay to replace relay3.

Last pic in post #1. I assume that's fan #2. It looks like you have + run from fan 2 to #30 relay 3.

Yes, (blue wire) red wire on fan 2 goes to pin 30 on Relay 3

I think you have 87 and 87a inverted on Relay 3.

Is that your neg side on fan #2 (red)?

Well, I connected (purple) 87a on Relay3 to 87 on Relay2 as well as the red wire on Fan1

87 (black) on Relay3 is connected to the black wire on Fan1 and both are grounded inside the front trunk

No polarity markings on the fan wires, so I assumed black is negative and red is positive.

Fan1
Red fan wire (purple on schematic) to 87a R3 and to 87 R2
Black fan wire (black on schematic) to 87 R3 and ground

Fan2
Red fan wire (blue on schematic) to 30 R3
Black fan wire (yellow on schematic) to 87 R1

The fan's black wire should be going to relay 3. The other red wire should go to relay 1
Edit: this is for fan 2 wiring that you mentioned in the previous post.

Here is another diagram for the same configuration.Click to view attachment

Fan1
Red fan wire (purple on schematic) to 87a R3 and to 87 R2
Black fan wire (black on schematic) to 87 R3 and ground

Fan2
Red fan wire (blue on schematic) to 30 R3
Black fan wire (yellow on schematic) to 87 R1

So Fan1 is correct? And...I have my wires on Fan2 reversed?

When I saw the "battery hot" in the schematic going to 30 on Relay1 and 30 on Relay 2, I assumed "30" on Relay 3 would also be "positive."

Yah, fan 2 colors are reversed

Edit : relay 3 is switching ground. Is there diodes on the fan motors?

Thank you all for "holding my hand" through this!!! Refresh a few wires tomorrow, and I'll give it a whirl.
Thanks again,
Mark

No. Should I add diodes? If so is there a recommended size and should there be one on each fan wire and which direction should they point. Yikes

No don't add them. I was trying to figure out what was causing the direct short that melted your wires. I wonder if those fan motors aren't electrically isolated? Tomorrow, measure the continuity from the black wire on the fan (wires not connected to anything) to chassis ground. I'm hoping to see infinite resistance, which demonstrates the motor is electrically isolated from chassis ground.

If you connected a direct + wire to #30 on relay 3, and you switch to high speed, this will short the + directly to ground and burn!!!

C1 grounded

Here's the current path, C1 gets ground operates relay #1 , #30 supply's bat to pin 87 which is wired to one side of the fan motor #2 the other side of the motor is
wired to #30 on relay #3 which is not operated and flows current to #87a which
is wired to the other fan motor the other side of this fan motor is grounded. Both
fan motors are in series now ( each motor has 6 volts to them).

C2 grounded ( note C1 not grounded)
Relays 2,3 operated, Relay' #2 supplys 12v #30 to #87 which is wired to motor#1
the other side of the motor is wired to grounded ( fan #1 has 12 volts Full speed)
relay #3 #30 is wired to fan motor #2 the other side is wired to relay #1 #87
motor #1 will not operate till C1 is grounded.

So what you have is a 3 speed operation if the fan motor can run on 6 volts

C1 grounded both motors have 6 volts on them
C2 grounded Motor #1 fullgrounded
C1 and C2 gounded motor #1 and #2 full speed

Exactly What would be neat, if you could add a sail switch in the airstream. This would turn off all the fans when you hit 60mph, or whatever you calibrated it for.

If relay #3 is the incorrect relay, and 87 and 87a are joined , then that will cause the reaction you are describing. Make sure on #3 that when 85,86 trigger...30 does not go to both 87 and 87a ....got it ?

The terminal numbers on these relays are all standardized; it is not possible to have some where 87a is normally-open and others where it is normally closed. ..

That's what I was pointing you to in post#15.

So is this issue resolved?

The circuit as drawn looks correct.

Must be something in the wiring.

As mentioned before, check things one at a time to make sure all is correct.

Building the entire circuit then applying power is a common development procedure. It is also referred to as the "flame test" since schematic or wiring issues sometimes lets the smoke out of something.

Refreshed the wires, corrected the two wires that were reversed on fan 2. Checked each fan and they are completed isolated.

Hooked up power...no smoke Yeah, but no fans, sort of.

Sensor 1 Grounded: Relay 3 clicks but no fans-no melting etc.
Sensor 2 Grounded: Fan 1 blows, but not fan 2--no melting etc.

I went through and re-read everything again from everyone and several people mentioned the possibility of Relay 3 possibly being the problem. I pulled the relay out were I could look real close and the numbers and noticed that there were two 87s--the typical 87 on the side and another 87 where 87a is normally located.

Searched the web for all the different possible 5 prong relays--there are three types that look very similar, but function differently and a couple more that have diodes added. If you look closely at the relay I was sold, it is wired internally differently than what the schematic calls for. Am I looking at this correctly?? If so, I need to source another 12v 20/30a 0 332 209 150 Bosch relay. A quick check of our FLAPS came up empty...so I guess I'll need to order one. I sure hope this is the problem. Ebay Relay
Click to view attachment
Click to view attachment
Click to view attachment
Click to view attachment
Click to view attachment

Revisit post 14. I strongly encourage buying some beefier relays. The ones purchased at the FLAPS are great for lights or horns. Electric motors draw a bunch of current (LRA) when first starting up. For this reason, I recommend using overkill sized relays for your application. It's less likely to leave you stranded on the side of the road.

Also, what happens when you ground sensor one and sensor two together? Both fans should be on (full speed)

I didn't try grounding both at the same time after sensor one failed to start both fans at 1/2 speed--figured that I better not push my luck--I pulled R3 to get a closer look at the numbers.

You should try it, sounds like the whole problem was switched fan wires. C2 will never ground by it self. C1 will ground at 180F, then C1 and C2 will both be grounded at 200F

That makes sense, C2 would never be grounded by itself...will try that tomorrow.

Although since C1 did not start both fans at 1/2 speed, I still have an issue.
C1 grounded both motors have 6 volts on them
C2 grounded Motor #1 fullgrounded
C1 and C2 gounded motor #1 and #2 full speed

Looks like Relay 3 is your problem. It is a single pole, single throw (SPST) switch.

This effectively shorts both contacts of Fan 2 and when power is applied to Fan 2 through Relay 2, it shorts battery to ground and melts wires.

Check that the other relays are 87-87a type. If so, you can swap Relay 3 with Relay 1 or 2 since Relay 1 and 2 only needs to be SPST switches.

That's true. My other two are Bosc Bosch 0332209150 Main Relay

This was mentioned in post #5. Are you really reading our replies?

I just assumed that his relay 3 was a 5 pin

Wait wait wait, I'm confused now. From his picture, the middle relay looks to be relay 3 and appears to be a 5 pin SPDT relay. What am I missing here?

You need to STOP what you are doing and begin all over. You have entered what we called in the trade as CHASING YOUR TAIL.
1- test all components for proper operation, fans, relays in both energized and de-energized states. Use an ohm meter between 30 and 87/87A to make sure the contacts are good. After a high current event, the contacts may be welded. By testing I mean hook up a multi-meter to 30 and 87. With no power to 85 and 86 what is the reading? Now apply power to 85 and 86, what is the reading? Now repeat for 30 and 87A. Once all of the relays are known to be operating correctly, test both fans, both by themselves and in series.
2- once all components are known to work as they are supposed to, hook the circuit up one wire at a time to the wiring diagram in your first post. That diagram is good.
3- listen to one person's advice only, and follow that advice one step at time. Too many cooks in the kitchen will ruin the soup!!
4- fuse that circuit before any more testing with power.
5- test one sensor grounded and relays operating to run fans and see that it is working correctly before proceeding any further to second sensor.
Google "basic DC circuits" and study up on how circuits work, it will not be wasted effort.
Tom

yes, it is a 5 pin almost identical to the Bosch...thank you FLAPS. Unfortunately, the Chinese knock-off labeling on the package doesn't help. My ignorance not knowing there was such a relay that looked the same with 5 spades with 87 printed next to both was different than 87 and 87a. Obviously, my FLAPS didn't either since I gave them a BOSCH and asked for an identical one. Live and learn. Oh, Well.

Yep, post number 7. if it was a snake, it would of bit me! Good catch

I really appreciate everyone's input. I've learned so much through this pain in the ass upgrade. The best thing is...I think I actually understand now what's going on with this schematic.





Post 7
Click to view attachment

Mike, yes, you are 100% correct ! Sometimes my brain knows what it is thinking but I totally f up getting it out. Bosch makes a 5 prong 20/30 amp relay that triggers to 87/87. That is what the middle relay looks like in the posted picture. Alfa used them for horn relays... Thank you for catching my mistake. Do you see what I was trying to say about how this substitution in the circuit could be the problem ?