I know I'm missing something here, but I've done searches on this.. and spent hours researching it, but this is the same problem most of the guys here are having with their cooling fans. Only I have replaced the fan switch on the head, the fan relay, the coolant temp sensor, and all of the pigtails (wiring) but i still can't get the fan to work it's regular cycle. But it will work if I turn the A/C on. I've grounded the wire from the fan switch, and the fan comes on. The only way the fan works besides the A/C is if I ground the green/white stripe on the relay itself, and I've already blown two relays doing it that way. I've checked for shorts and there are none and I've checked the fuse I think I've got all the bases coverd but Im still not getting any results. The whole cooling system is brand new from the radiator to the hoses, and heater core have I missed something here?? PLEASE HELP!!!!!

 

I think I stumped everyone.

 

Does your fan come on when you fetch a SES code?

 

Yes and when I turn the A/C on it does too.

 

gotta be a broken wire somewhere?

 

I would check for a break in the wiring harness. There are some areas where one wire splits into two or three with a crimp. Just black reinforced tape is around the crimp so its not water proof.

One of my friend's '87 LG4 IROC had the same problem you are having. The car is totally rust free and looks like its never seen a winter. It turned out to be a crimp in the wiring harness had rusted into two. The way the factory had positioned the harness with plastic loom slot facing up, water would run off the top of the cowl and poll into the wire loom.

I would pull the harness up from the back of the engine and check those crimps. If you have a factory service manual it will be a a lifesaver because it tells you where all the splices are in the harness.

 

How hot is it getting w/out fan coming on? Factory switch is set at to come on around 235 deg and of at 220. If you ground the wire from the switch in the pass cyl head and the fan comes on, I don't see a problem with your wiring. An 89 turbo T/A switch comes on at 208, try that. Or run a manual toggle switch using the fan switch wire.

 

I have a 89 turbo T/A fan switch I'm going to try that as well as a 180 deg thermostat. Ive checked all the wiring and connections and everything seems to be ok.I'll post back later to tell of the results. In turn maybe I can help some of the other guys here with the problem I'm having.Thanks for all of the help guys.

 

Just found out that the fan does NOT come on when pulling codes Now what is it the computer or the prom???

 

 

If I let it sit at idle it goes into the red on the temp gauge. This is what I have new in it so far....

ECM
Fan switch on the passenger side head
Fan relay
All new connectors to everything related
Coolant temp sensor
Radiator
Heater core
Hoses

Any other ideas fellas??
Im at a loss.

 

Does your temp gauge have numbers? If so, how hot does it get?

 

the temp gauge goes as follows: 100 on the bottom, 220 in the middle and 260 at thr top of the red line the gauge does not hit the 260 mark but right below it.

 

If coolant isn't boiling over when it gets this hot, then either bad temp. sending unit (drivers side head between cyl 1 & 3) or bad gauge in instrument cluster. You might want to buy cheapo mechanical gauge, install in place of temp sending unit, and see how hot it is really getting. I'll bet fan will come on around 235 degrees. Also, how hot does it run driving down the highway (55-65 mph)?

 

Right below the 220 mark, I ran out to a dealership today to pick up a couple parts, and it was a combination of city driving and highway. I did however have the fan grounded so it was on.

 

Should run 180-195 on the highway, or with fan on in traffic(unless it's a 100+ degrees out). I would try a temp switch (sender) first. It's the one wire sender in the drivers cyl head, and doesn't cost much. If that doesn't fix it, might be the gauge. Either way, I think your gauge is showing the wrong temp.

 

I have a new switch in it. I got the turbo T/A one, and I got a 180* thermostat also that I'll try. When I had a 180* in it before, and I didn't have any problems at all with the fan coming on. And the temp gauge stayed right between the 100 and 220 mark, even when it was 90 degrees and above outside. I will go tomorrow and get a sending unit and if needed I have another temp gauge. Thanks for the help Lo-tec I'll let you know what happens tomorrow..

 

Well.. sucess!! I put the Turbo T/A fan switch in, and put the 180* thermostat in, and rechecked all the connections, and turned the car over let it warm up. And right before the temp gauge hits 220* the fan comes on. Lo-tec thanks for the advice, and helping me. My cooling troubles are over thanks to you dude.
:hail: :hail: :hail: And thanks to the others who posted their ideas.

 

Hope its not too late, but go to the technical article section of this site and in the electrical section there are 2 articles by Willie about wireing an adjustable temp fan switch which is a very *** article to read. Even if your fan is working good now it wont hurt to check it out.

1 is for single fan the other is for dual.