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How do I wire my coolings fan to stay on at ignition?

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04GPWhite

New member
I've read that u can't cut the yellow wire that run into temp sensor and fans would come on at ignition and u would still keep ur temp in your gauge. Is this true and is their any other easy ways? The reason being is that my fans are not getting a signal from my sensor that the car engine is hot. I've diagnosed everything else and this is what I've came up with. Car sits at 3/4 on temp gauge when idle and drops when on freeway. Any help thanks
 


Coolant flush two days ago, replaced ect, replaced thermostat, replaced relay, checked all fuses and bled coolant system. Fans turn on with a/c, fans turn on when I unplug ect. So I'm guessing problem lies with the wires. Car will overheat with no fans, car temp stays at 3/4 mark with no fans. This all happened after the 90 degree coolant lines busted.
 
Is it possible you replaced a bad ect with another bad ect? or the replacement ect was the wrong part?

I'd say fix the fan problem properly instead of a band-aid approach of always on with ignition.
 


Is it possible you haven't let the car heat up to 216F degrees? That's about the temp the fans first kick on at. The high setting is at 228F degrees. Keep in mind...I'm the messenger not the dumb programmer.
 


Normal to have thread sticking out. It's an NPT fitting. So it's tapered.

How hot is 3/4 on your temp gauge? If the gauge went bad, you might be trying to fix the wrong thing.
 
Ok, so you are saying, you don't know how hot the engine is running when the gauge is that high. Got it.

I'm suggesting that potentially your gauge is incorrect. By scanning the temp, you would know what the pcm sees for a temp. maybe there's a reason the pcm isn't seeing the correct temp and not turning them on. If I'm going in a direction you'd prefer not to go, please say the word and I'll say.. jump any ignition source in the underhood fusebox to the trigger of the two fan relays and that will make them come on whenever the ignition is on.

Most folks would prefer not to set a check engine light, or have the fans work properly. That's why I went in that direction.
 
BillBoost37 said:
Ok, so you are saying, you don't know how hot the engine is running when the gauge is that high. Got it.

I'm suggesting that potentially your gauge is incorrect. By scanning the temp, you would know what the pcm sees for a temp. maybe there's a reason the pcm isn't seeing the correct temp and not turning them on. If I'm going in a direction you'd prefer not to go, please say the word and I'll say.. jump any ignition source in the underhood fusebox to the trigger of the two fan relays and that will make them come on whenever the ignition is on.

Most folks would prefer not to set a check engine light, or have the fans work properly. That's why I went in that direction.
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I want the fans to work properly but I also use this car as my DD. I dont want anything worst to happen. Im figure that maybe the wiring is bad, thats why the pcm isnt getting a signal to turn the fans on. I will look into reading the engine temp and see if it matches the guage.
 
BillBoost37 said:
Normal to have thread sticking out. It's an NPT fitting. So it's tapered.

How hot is 3/4 on your temp gauge? If the gauge went bad, you might be trying to fix the wrong thing.
Click to expand...

gp04cluster.jpg
Using Torque, these are my best approximations for temp gauge positions on the 2004+. With the cold line at 140, the line increments are about 9 Farenheit. Most other GM uses 210 as a center line, I assume this is the intent with Pontiac, and I assume that all other GM is 212 at the 210 line. I read somewhere (cant remember where) that GM's with gauges that go to 260 are actually 265.


Under normal conditions, crusing with the AC on, my gauge will be a little above the 194 line, a little below if not using AC or its very cold out. At idle, it will reach the 221 line where the fans kick in and drop it back to the 203 line (assuming the shut off point is 200?)

This is the highest my car has been under my ownership, my water pump failed and I pulled into a Wendys when I noticed the coolant smell and the steam.

Keep in mind that these gauges are not meant to be dead on accurate to the degree, the PCM reports on a several second delay. For example, my gauge has been on the 194 line when torque reads anywhere from 192 to 197. This just gives you an idea to within 5* +/-
 


Chadgervais said:
View attachment 10810
Using Torque, these are my best approximations for temp gauge positions on the 2004+. With the cold line at 140, the line increments are about 9 Farenheit. Most other GM uses 210 as a center line, I assume this is the intent with Pontiac, and I assume that all other GM is 212 at the 210 line. I read somewhere (cant remember where) that GM's with gauges that go to 260 are actually 265.


Under normal conditions, crusing with the AC on, my gauge will be a little above the 194 line, a little below if not using AC or its very cold out. At idle, it will reach the 221 line where the fans kick in and drop it back to the 203 line (assuming the shut off point is 200?)

This is the highest my car has been under my ownership, my water pump failed and I pulled into a Wendys when I noticed the coolant smell and the steam.

Keep in mind that these gauges are not meant to be dead on accurate to the degree, the PCM reports on a several second delay. For example, my gauge has been on the 194 line when torque reads anywhere from 192 to 197. This just gives you an idea to within 5* +/-
Click to expand...

Going off your picture, my car sits at about 212 mark, and still no fans. Before my 90 degree coolant lines busted my car sat around 176-185 mark. I just dont think its normal to have the temp that high. What if I travel to LA or San Fran or Yosemite? I go through mountains and I believe my car would overheat.
 
If you are idling at 212 that's okay. Your fans don't kick in until you hit the next line up. Its higher than u like to see but its not dangerous.

212 is towards the top end of normal. Over the summer I took a highway trip with a water pump that was on the verge of failure. 97 outside and 215ish under hood. If you can keep it on the highway you'll be OK.... as long as you don't hit traffic.
 
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04GPWhite said:
so how do I lower this? new water pump?
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hard to say, you said this happend after your elbows failed and did not resolve when you replaced them? Sounds coincidental to me, unless the inside diameter of the new ones are much smaller, impeding flow.

There are many things that can cause higher than normal temperatures, it could even be ignition timing. One thing i noticed after replacing the water pump is that when the stat opens, there is a noticeable drop in the gauge, so the water flow is MUCH stronger now. It still goes to 221 when i idle for a few minutes, but it drops faster when i move again or the fans come on.

When you say "three quarter mark" do you mean 212 or 248? You implied 212 in an earlier post, which is the half mark. It weirded me out when i first got the car to see the gauge go past half, but ive been assured that its normal as long as the fans come on.

212= OK (idling, hot day, mountain driving, stop and go city traffic)
248= Problem
 
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