ReznorZ28

My car was recently in an accident... well I got all the cosmetics done, but now my fans wont turn on. I know that the fans themself work because I can hook them up direct to where they are running all the time but thats only a temparary fix(and doing that I have to pop the hood everytime I turn the car off to unplug the wires and vice versa).. I bought 2 new relays(for the primary and secondary fan relay) for the fuse box under the hood and still the fans dont trigger themselves on when the car starts to warm up. What do you all think the problem may be?

FastGuyJR

Do you have an SES light? If you do, it may indicate a problem with the circuit. Try popping the plastic cover off the relay and manually triggering it to see if the fans come on. You can move that relay between the high power and low power fan relay sockets to test both of them.

ReznorZ28

No, I dont have a SES light on... all guages read normal(except the airbag light, but thats because the airbags were deployed in the accident ).... so where does that leave me since I dont have a SES light going off? someone please help... I want to try everything before I get raped at the dealership or anywhere else...

FastGuyJR

Try the relay test anyway
You're not testing the relays, just that u can use the relay to manually trigger the fans. It's quick and easy and a helpful diagnostic.

ReznorZ28

Can I pop open the relays without breaking their housing/case?(I dont want to break them, they were $12.00 a piece at autozone ) And when I do, how do I trigger them? Like I said, if I use a wire and connect two of the terminals the fans turn on, but I wouldnt know how to do it on the actual relays... if you can explain in a little detail it would be great... otherwise I will try and pop them open and see if I can just figure it out.

irocdreamer

In the meantime take out your AIR pump fuse. Your SES light will come on but your fans will run all the time. That'll save you from popping the hood all the time.

shoebox

That is also one way of testing whether your pcm is capable of turning the fans on. If it does, then all the wiring and relays in the fan circuits are intact.

Another way to test the fans on your 1994, is to jumper the "A" and "B" terminals of the DLC and then turn the key ON (don't start). Turn key OFF and remove jumper when done.

Be aware that factory fan programming does not turn the fans on until 226º. If you feel that your car is actually getting that hot or hotter, you might have a problem with the temp sensor in the water pump. It is the one that provides info to the pcm. If you have a scanner, you can look at the temp the pcm sees and determine what is going on.

94_formula

i heard it was 242??? both are kinda hot IMO

ReznorZ28

Thanks for the help, Ill check into all of this but I was reading my manual about the temp sensor and I dont find where it says there is one located within the water pump. my Haynes manual says that the temp sending unit is located somewhere around the left exhaust manifold.

FastGuyJR

There are 2 coolant temperature sensors. One goes from the driver's side cylinder head to the gauge on your dashboard. The other goes from the water pump to your PCM.

JR

ReznorZ28

How could you tell if that one went bad, and if it is bad, can you just replace the sensor or do you have to replace the whole waterpump?

Man, I read this whole chaper in the Haynes manual on the cooling, heating and air conditioning systems and it doesnt say anything about a sensor in the waterpump... it just tells me about the one on the cylinder head. This book sucks!
but thanks again for your help!

FastGuyJR

Like shoebox said, you'd need a scan tool that hooks into the ALDL connector under the dash to see what values your sensor is reporting, which would tell you if the sensor has gone bad or not. I don't know if the part numbers for the 2 sensors are the same, maybe you can switch them around? If you swap them, you'd need to drain the coolant. Anyone feel free to chime in here, of course.

JR

PS Let's get some step-by-step pics on that LS1 front end conversion

shoebox

Info on how to test the sensor and connection.

ReznorZ28

Hey Shoebox, I just got my car back from the paintshop yesterday so I havent been able to troubleshoot until today. I put the relays back in and removed the air pump fuse. The fans do turn on when the SES light comes on. So I gues that means that the wiring and relays in the fan circuits are intact like you said... but where do I go from here?

Another thing thats strange, is that from time to time I get the low coolant level light come one... and when I check my coolant level it is full... what can be causing this?

shoebox

Sounds like your fan circuitry is ok and the pcm is capable of turning them on. The thing that is not known is what temperature the pcm is seeing. That is where the scan tool would come in. You can use the testing directions on my Tech Page to tell if the sensor or wiring is good, but that still does not tell you what the pcm actually sees and what it is doing. Oh, and the sensor you want to test is, for sure, the one in the front of the water pump.

The low coolant sensor is prone to acting up. Your choices are to remove and clean (possible fix), replace or unplug it. Unplugging it will not cause the SES to come on. The pcm does not monitor this sensor. It will merely disable the light on the dash. Pics of the sensor and replacement info is on my Tech Page.