Dual Fan wiring question

[87GNcospg]

I installed the dual fans from http://www.allstarperformance.com/product.htm?prod=720 and installed the racetronix harness.

i have a manual switch wired in. the switch is a single throw double pole switch so i have control over high and lo. the switch is wired to a ground, one wire going to green wire from high speed relay, and another wire to the correct green wire from the low speed relay.

first question. is the above fan just a one speed fan? because i tested it before i soldered everything in place and jumping either wire from the high/lo relay turns the fan on at the same speed.

i am also having a problem with the switch for the fans. the switch works fine until the car starts to get to normal operating temperature. past 170 or so. then the switch stops working and the computer will not turn the fans on either. i can shut the car off, let it cool down and the manual switch will continue to work. all the connections are good. i checked them over and over again. what would cause this?

 

[Racetronix]

Please pose your question in this thread

http://www.t6p.com/forums/showthread.php?t=5970

along with details as to where you interfaced the switch.

Please make reference to the schematic posted in this thread.

 

[87GNcospg]

posted it

 

[87GNcospg]

i still have not been able to correct this problem. i spent the better part of the day today re-checking solder connections. everything was fine. switch still works but will randomly stop working once the car gets past 175 degrees. sometimes the ecu will switch it on and sometimes it wont.
what sensor,relay,timer etc would cause this kind of erratic behavior? i have brand new hi/lo relays.
when the switch stops working it will always begin to work again once the car cools off. . . .

 

[87GNcospg]

im not sure what to do about the situation. i would love to drive my car to the track this saturday but wont be able to if this problem is not resolved. i guess i will just replace the coolant fan delay relay and the coolant temperature switch. not sure what else can be replaced to hopefully fix the problem.

 

[pacecarta]

im not sure what to do about the situation. i would love to drive my car to the track this saturday but wont be able to if this problem is not resolved. i guess i will just replace the coolant fan delay relay and the coolant temperature switch. not sure what else can be replaced to hopefully fix the problem.

you dont even need the delay relay , unplug it completely

your car has a high and low relay from the factory , the low side is activated by the ecm only by grounding through the green wire and will only turn fans on if the coolant signal from the sensor on the front of the manifold is working correct and the chip is programed to turn it on
most aftermarket chips turn the fans on at 170 , the stock chip wont come on till 195 or so .

the high speed relay activates by the a/c pressure switch behind the compressor (wont activate if a/c isnt charged properly) or by the temp switch (overheat switch) on the top of the manifold by grounding through the green /yel stripe wire ,


in using the RTX harness and going to the dual fans the realays really arent high/low specific relays anymore as they need both to be on to get high speed fan operation so either relay on by itself will provide low speed fan.
if you ground the green wire at the relay you should have low speed fan
if you ground the green /yel wire at the high speed relay you will have low speed fan
if you ground them both you will have high speed

for your car with the rtx harness the fans normally operate in low speed . if temps are above the chips preset turnon and a/c is turned on the second relay is energized and fans run in high speed

if your ecm isnt turning on the fans check the factory low speed relay and if grounding the green wire turns on the fans the relay is good so check the green wire to the ecm and its connection at the ecm , if still no good try another ecm
if grounding the green does nothing check the supply to the relay for 12v
, check the fuses in the rtx harness , if it has power and fuse is good replace the relay


if your still not working check the wiring you did at the fan to connect to the rtx harness

 

[pacecarta]

i dont see the switch you chose working for the rtx harness , yank it out till you get the fans to operate normally

i run a single rocker switch from the green with the other end of switch at ground for low speed , never saw the need to run these fans in high speed , they just work that good

 

[87GNcospg]

i dont see the switch you chose working for the rtx harness , yank it out till you get the fans to operate normally

i run a single rocker switch from the green with the other end of switch at ground for low speed , never saw the need to run these fans in high speed , they just work that good

which green wire are you splicing into?
having the computer control my fans is not a big deal. i would rather have manual control over them 100% of the time
grounding both wires on the hi/lo stock relays turns the fan on. the switch i am using is a single throw double pole switch. one wire to ground. one to green from hi relay and one going to green from lo relay. i followed this digram posted by racetronix on another forum http://www.racetronix.com/Manuals/RX-G7-DFH/RX-G7_Fan_Schematic.pdf

but you say that splicing into both stock relays will just give me the same low speed so i guess i didnt need an on-off-on switch. here is how racetronix said to wire the switch http://www.t6p.com/forums/showthread.php?t=5970

this problem is annoying because the switch will work 100% of the time UNTIL the car gets warmed up. once the ECM (or something) see's normal operating temperature its as if the circuit gets closed.

 

[pacecarta]

I wouldnt bypass the ecm controll or the high temp swicth for that matter , you dont want to go wot with the fans running and you dont want to go wot with high coolant temp , most chips will turn the fan off above 4.0 TPS so that you dont encounter problems
i had blown the low side fuse once on the rtx harness and if it had not been for the overheat circuit on the high side i would have boiled over
heres a pic of what i did on my 87
dont remeber why but i actually have it spliced into the highspeed relay green/ yellow stripe (not that it matters) it works fine for manual control when in the pits, . being on the high side does not interfere with the ecm grounding with key on and switch closed it will go into high speed if the coolant is above 168

i do not have the delay relay connected and never had any issues

 

[87GNcospg]

i am going to disconnect my wire going to the Low speed relay tomorrow morning. maybe since that wire is hooked up and usually the switch is closed on that part it may be interferring with the ECM.

i have it wired this way because the above racetronix post made it seem like i could have hi/lo speed operation. obviously that is not the case.

 

[pacecarta]

it will do high speed if you wire two switches as he shows and flip both switches , or if you flip highand coolant is above chip turnon point . or run the a/c and coolant is above chip turnon point ,

the diode in the diagram is not needed if you unplug the delay relay

 

[87GNcospg]

so having one wire from low speed relay to switch, one wrie from high speed to switch and a ground is going to just give me low speed when my on-off-on switch is thrown either direction.

to get a high speed operation i would have to have a wire connecting both relay wires then going to one of my on switch positions, correct?

anyways i need to figure out why my switch is closing when the car gets warm :tongue:

 

[pacecarta]

i looked at his thread that referenced to a single pole dual throw (on -center off -on ) switch you stated you used a single throw dual pole which is a different configuration

with the switch as you state you can select high or low but not manually as conditions need to be met with key on to get high speed ,
for true manual control you need to have a dual throw dual pole switch(on-off-on but with two seperate poles) . connect the low (green) to the top , ground to the common center poles and hi (grn/yel) and low (grn) to the bottom poles
this allow you to flip down and ground the low side relay only , center is off and in the other position (up for high) grounds both high and low and keeps them seperate when returned to center (dual pole will accoplish this)

i went by the diagram not what he posted and only installed the one switch

 

[87GNcospg]

thanks for all the help.
i dont know if i mentioned the switched i used but i did purchase the switch that was recommended in the racetronix thread. single pole double throw switch with center off position. ON-OFF-ON

ill try what you stated though.
thanks again

 

[87GNcospg]

it will do high speed if you wire two switches as he shows and flip both switches , or if you flip highand coolant is above chip turnon point . or run the a/c and coolant is above chip turnon point ,

the diode in the diagram is not needed if you unplug the delay relay

basically i can use two simple rocker switches. one switch wired to ground and Hi relay. Other switch to Lo and ground. flip one switch, lo speed, flip both and get high speed. i hope i got this. i would rather build a motor than do semi-simple wiring

 

[pacecarta]

basically i can use two simple rocker switches. one switch wired to ground and Hi relay. Other switch to Lo and ground. flip one switch, lo speed, flip both and get high speed. i hope i got this. i would rather build a motor than do semi-simple wiring

yes

 

[87GNcospg]

this may be a little confusing but here goes. . .
i put everything back to stock and wired up a SIMPLE rocker switch. what i mean when i say back to stock is i removed my wiring for the previous switch and redid it with a simple power ground from the hi relay. rx harness is still connected. fuses have power, relays are good. switch works fine until 160ish degrees then it stops working and the ecm will not turn on the fan. if i leave the switch off and let the car get up to 170 the fan turns on by itself. if i let the fan turn on by itself yet i throw the high speed switch the fan will continue to run then stop once it gets below 169. then the fan will not turn on by the ecm or switch. once the temperature drops below 157-159 the switch begins to work again. . . . . i tested this abnormality 3 times. took me about an hour to wait for temps to drop back down each time i tested it. each time the temps dropped below 159 the switch began to work again.
i also swapped ecms to see if it would change. it acts the same way.

SOOOOOO what would cause the fan not to work once the car gets to operating temperature? any specific part that MAY cause this weird behavior?

 

[pacecarta]

the ecm control of the fans is fairly simple ,
the coolant sensor at the front of the engine provides a value that is used to determine engine temp , if the temp is above the chip setting the ecm grounds the green wire to the low speed relay


if the ecm is getting correct info from the coolant sensor ( what does your scanmaster read or scan tool show for temp ?)
if temp is not accurate either replace the temp sender and /or check the wiring
check the yellow wire at the coolant sensor (front of engine ) to pin c10 at the ecm (disconnect ecm connector) , with a meter verify that that wire is complete without any grounds or shorts
check the black wire (terminal B) at the coolant temp connector to pin D12 at the ecm , that wire is for analog low ground and also goes to the tps ground (terminal C) and the air temp ground ((terminal A)

now you are certain the ecm is recieving correct info on temp so check the green wire from low relay , unplug the low relay and with an ohmeter check the green wire to pin D2 at the ECM again looking for any grounds or shorts , now you know the wire is good
recconnect ecm now see if its indeed grounding the green wire when temps are above the turn on temp and that it shows no connection to ground below the turn off point , if it doesnt and you know ecm is good than maybe the chip is faulty

thats it , if it still doesnt work i think it needs an exorcism

 

[87GNcospg]

thats it , if it still doesnt work i think it needs an exorcism

:biggrin: . i think im going to do the exorcism first. . .

thanks for the help. ill have time this weekend to do all the final checks.