1G how do i wire (properly) 2 fans to come on at same time with temp sensor

[enriquez2000]

Right now I have them wired the wrong way... but this wont work with the 2x 20 amp fans I have coming.

I know on 2gs you can jumper the ac relay but my recollection is that its not possible on a 1g(i could be wrong but i dont remember a 2nd relay).

Do i need to just run a 40 amp relay and fuse wired in how I have it now which is both fans running parallel off the switch?

Just want to do it once and do it right and as painlessly as possible if I can.

 

[Tiki2777]

I wired the fans into the stock connectors, then changed the numbers the ecu needs to read in to turn the fans on with ecuflash. I set mine to turn on pretty early because of the insane heat here in Nebraska lately.

 

[enriquez2000]

I wired the fans into the stock connectors, then changed the numbers the ecu needs to read in to turn the fans on with ecuflash. I set mine to turn on pretty early because of the insane heat here in Nebraska lately.

cant do that on 1g... if i want them on earlier i have to find a different fan switch

 

[luv2rallye]

If you want to do it right and electrically safe you need a separate relay for each fan. Do you (are you) want to use the original harness fan connectors and want to use the original relays OR are you wiring everything?

(Note: Tiki is talking about the 2g where the ECU controls the fans. In a 1g it doesn't.)

 

[enriquez2000]

Im thinking i can run the passenger side off the main realy(existing) then i will piggy back a relay off those for the second fan.

I would rather use stock wiring to get both to come on simultaneously but i dont think there is a way

 

[luv2rallye]

What year is it and do you still have a functional thermo sensor switch in the bottom of the radiator (which turns fans on)?

 

[enriquez2000]

What year is it and do you still have a functional thermo sensor switch in the bottom of the radiator (which turns fans on)?

my car is a 93 and yes the thermo switch works.. it seems to come on at 203(a bit hotter than I like).

I should be able to just run a relay piggy backed onto that wiring to power the 2nd fan though

 

[enriquez2000]

thinking something like this should be ok......

 

[luv2rallye]

my car is a 93 and yes the thermo switch works.. it seems to come on at 203(a bit hotter than I like).

I should be able to just run a relay piggy backed onto that wiring to power the 2nd fan though

Yes, if you piggy back a 2nd relay off the radiator (aka passenger) fan motor relay it should work. However you must connect it in parallel (not series) with that relay except for the fan output like this:

Connect new wires from radiator fan motor relay:
- pin 3 goes to new relay pin 30 (or relay main positive power)
- pin 4 goes to new relay pin 86 (or relay coil positive)
- pin 2 goes to new relay pin 85 (or relay coil negative)
(Note: don't reverse pins 85 and 86 or you will blow out any internal relay flyback protection diode - ie. pin 86 must be more positive than 85)
- New relay pin 87 (or relay switched power out) to 2nd fan positive (and 2nd fan negative to ground).

Here is the factory fan circuit: http://www.dsmtuners.com/threads/slim-fan-wiring-driving-me-nuts.502763/#post-153584435.

Here is the typical aftermarket relay: http://www.ado13.com/techs/relay.htm
And what's inside: http://www.the12volt.com/relays/relays.asp

Attached is the way to wire the fans should you have to wire everything from scratch.
Note: You will have to increase the fuse value (and wire size) if you really have two 20A fans. Most fans don't draw the current they say (it's a peak value). Example: The stock 15A fans really only draw 10A steady state.

 

[enriquez2000]

Yes, if you piggy back a 2nd relay off the radiator (aka passenger) fan motor relay it should work. However you must connect it in parallel (not series) with that relay except for the fan output like this:

Connect new wires from radiator fan motor relay:
- pin 3 goes to new relay pin 30 (or relay main positive power)
- pin 4 goes to new relay pin 86 (or relay coil positive)
- pin 2 goes to new relay pin 85 (or relay coil negative)
(Note: don't reverse pins 85 and 86 or you will blow out any internal relay flyback protection diode - ie. pin 86 must be more positive than 85)
- New relay pin 87 (or relay switched power out) to 2nd fan positive (and 2nd fan negative to ground).

Here is the factory fan circuit: http://www.dsmtuners.com/threads/slim-fan-wiring-driving-me-nuts.502763/#post-153584435.

Attached is the way to wire the fans should you have to wire everything from scratch.
Note: You will have to increase the fuse value (and wire size) if you really have two 20A fans. Most fans don't draw the current they say (it's a peak value). Example: The stock 15A fans really only draw 10A steady state.

so my picture above should be correct if I pin it out properly on the relay... I was just too lazy to label the pins

 

[luv2rallye]

No your picture looks totally wrong.

 

[enriquez2000]

No your picture looks totally wrong.

Explain please.. now im lost

 

[luv2rallye]

- Well for openers you don't even have 2 relays.
- The battery positive needs to go to main power in on both relays (pin 3 on existing passenger relay and pin 30 on new driver relay).
- New driver relay power out (pin 87) goes to driver fan power in only (no where else).
- Passenger relay power out (pin 1) goes to passenger fan power in only (no where else).
- The other two new driver relay control wires just connect to the existing passenger relay's control wires: New driver relay pin 86 to passenger relay pin 4. New driver relay pin 85 to passenger relay pin 2.

 

[enriquez2000]

- Well for openers you don't even have 2 relays.
- The battery positive needs to go to main power in on both relays (pin 3 on existing passenger relay and pin 30 on new driver relay).
- New driver relay power out (pin 87) goes to driver fan power in only (no where else).
- Passenger relay power out (pin 1) goes to passenger fan power in only (no where else).
- The other two new driver relay control wires just connect to the existing passenger relay's control wires: New driver relay pin 86 to passenger relay pin 4. New driver relay pin 85 to passenger relay pin 2.

i was trying to use existing relay(stock) which would then fire the 2nd relay turning the 2nd fan on

 

[luv2rallye]

You don't want to do that because both fans current then goes through the one relay which will overload it as well as it's not safe. Plus you don't show it connected right to even do that. As well as if that one relay goes out then you lose both fans. My way one relay can go out and the other will still power the other fan.

 

[enriquez2000]

So 2 relays wired into the circuit using the stock wiring as a trigger for both... can i ground everything together or should i body ground the fans?

 

[luv2rallye]

The fans should have their own negative wires connected to ground (chassis). Separate would be best but you can connect them together and then to ground if you use a larger wire for the common to ground part. Fan body does not need to be grounded.

 

[enriquez2000]

This better?

 

[luv2rallye]

Much. The blue (relay control) wire then ends up going to the ignition switch (make sure you have +12v there only when ignition key is on). The black (relay control) wire then ends up going to the thermo sensor switch at the bottom of the radiator (it connects {switched on} to ground to turn the fans on when water is hot enough - floats {switched off} when water not hot enough).