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

Easy Performance - Hi-Lo Fan Switch #EP-HLFS

When was the last time you had a coolant flush?

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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.

what will cause the fans to kick on with a cold start

Defrost aka AC

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.

Originally Posted by BillBoost37

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.

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* +/-

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.

Originally Posted by 04GPWhite

so how do I lower this? new water pump?

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