kosmo38

iTrader: (2)

i started my ls1 and it started to overheat because the fan was not coming on. i wired my single speed fan like this:
g body instructions
85- hot in run and start
30-B+
86-c100 pin j for low speed temp turn on
87-20a or whatever necesary

the sitky faq has the low speed fan wired like this:

85- c100 pin j for low speed temp turn on
30-fan +
86-B+
87-switched +12
which one is correct?? i havent dug into to find the problem but i will this weekend and i figured some help wouldn't hurt. thanks

svt

this should work


edit:
you could put your 20amp fuse between 87 and Fan+, that would protect your fan, but not your relay, put the 20amp fuse between 30 and batt+ and protect both. You should also have a 10amp fuse between 85 and batt+ to protect the other half the of relay

edit edit:
so what did you actually connect your fan too?

G-Body

iTrader: (4)

Did you make sure that the fan settings were turned on inside the PCM? If your computer was for a truck that came with a mechanical fan the electric fan your on temps may not have been set up.

kosmo38

iTrader: (2)

i used g body insturctions and used a 20 a fuse between 87 pin on relay to + side on fan. now i havent had time to mess with it until just a few min ago.

the ecm was from a running 99 z that i pulled personally. when i had the emsiions and vats tuned out by a fellow sponor i did not ask for the coolant fan turn on temp be reduced. but i think the fan should still turn on.
i hardwired the fan to check fan and its ok. tried another relay and no change. im thinking maybe t stat stuck closed or ecm not putting out signal. how much volts does the ecm put out at pin 42 c100 blue? here is some quick checks i made.
i got 25.1 ohms between connector of pin 85 to gnd.
infinite ohms between 30 to gnd with key off
infinite ohms between 86 to gnd with key off
25.1ohms between connector of pin 85 and gnd
.3ohms between pin 42 of blue connector to connector pin 86

volts check
connector of pin 30 to gnd 12.7 v = batt volts
connector of pin 85 to gnd 0v key off
12.7 key on eng. off
14.5 key on eng on.


85- hot in run and start
30-B+
86-c100 pin j for low speed temp turn on
87-20a or whatever necesary

svt

The PCM pin 42 does not put out any voltage, it actually is a switch to ground.

Try just grounding the wire connected to 86 then turn the ignition on, this should force the fans to come on.

svt

Also, for your saftey and the safety of your parts, make sure all wires coming from the battery run through a fuse first. And also a word of caution about relays, 87a is always hot when 30 is hot, don't let it just dangle around with the end exposed.

G-Body

iTrader: (4)

Exactly what I was going to say. If the fans turn on when you try this then your computer is not giving them a signal to turn on.

kosmo38

iTrader: (2)

i will try this either tonight or tommorrow night and will keep you guys posted. thanks

kosmo38

iTrader: (2)

i removed input for 86 and grounded it and vuala the fan turns on. now i have to figure out why the ecm is not sending out the signal im going to start by trying to get ahold of scan tool and reading my cts. any thoughts ??

svt

Are you sure you are letting it warm up enough? I don't know the exact temperature but I believe stock the computer won't turn on the fans until its fairly hot. I believe the stock termostat is 195deg so the fans probably won't turn on until its 200+.

kosmo38

iTrader: (2)

the first time i noticed the fan wasnt kickin on was when it started to ping ever so slightly and thats when i shut it down. i knew i should of just bought hp tuner software. i hope i can get the fan turn on temp lowered without paying another $100. if thats the case im gonna buckle down and just buy hp tuners. should i go down to 160 degress for fan turn on??

svt

well, I'm no expert in this area, but I believe the thermostat and fan temps have to be somewhat in sync. if the fans come on and the thermostat is closed it won't really be doing any good to have the fans on. Also, if you need the heater in the winter then you have to consider that too, if the thermostat is closed you won't get any heat.

For my LS1, I bought the hypertech 160deg thermostat from http://www.texas-speed.com/shop/ (they seem to have one of the best prices and is a sponsor) that starts to open at 160deg and is fully open at 175deg, so I'm gonna start with fan turn on temp at 180deg and off at 170deg.

G-Body

iTrader: (4)

From what I have read the fans don`t come on until the coolant hits 223 degrees in the stock setting. You don`t want to have the fans come on as soon as the T stat opens or you will have the fans constantly running. I would set them to come on at least 15 degrees higher than the T stat opens. GM sets them up to turn on 28 degrees after the T stat opens.