87_LG4

Hi guys.

Ever since I put my engine back in after my rebuild, the radiator fan has not been working as it should. I can turn it on manually by engaging the A/C, but it won't come on when the engine gets hot. So the fan works, the relay works, but the temp switch doesn't. The switch itself is a brand new hypertech (4028 I think. The warmer one of the two). So I figured the wire must be shot 'cause I can't get the fan to kick in by grounding it. But I'm not sure it's the correct wire, as all the tech literature, handbooks and shop manuals I've read says it's supposed to be a dark green wire, where as mine is white. The wire going in to the relay is dark green however. Can anyone else confirm that their fan switch wire is also white. I have an 87 lg4 if anyone was wondering. Also, if my white wire is the correct one, where about / how far into the wire tangle does it splice in with the dark green one?

Thank you

chevyssman92

I had the same problem. So i just ran a toggle switch for it. Quick and easy

87_LG4

I thought about it, but I don't like the idea of having to keep an eye on the temp gauge. That's basically what I've been doing up till now by engaging the A/C when it gets hot, and it hasn't always been successful to say the least.

camaronewbie

I always read they were green. All mine were always green. But someone might have had to replace it at some point, and maybe they did a shabby job of splicing, and thus your issue. Sounds to me like you're gonna have to trace it down by hand to see where it goes and why it's not working.

Have you tried grounding the wire straight out of the relay (at the relay end) to make sure? Just scrape a small spot of insulation off the wire at the relay and touch a ground wire to that spot.

I hate the damned switches - I went through several (including Hypertech) and none worked longer than a month. I went to an aftermarket fan controller that probes the radiator fins and never looked back!

87_LG4

I haven't had direct access to my car lately, as it's been sitting at my parents' during the winter. I talked to my dad yesterday, explaining the issues, so he went out and disconnected the connector that goes into the relay and tested all of the wires with a multimeter. Then he shorted the green and the red/black wire (I think he said) and that fired the fan right up. Enganging the A/C also got it running. Unfortunately the carb isn't working right now, so I can't get it up to operating temps to test the temp switch, but as previously mentioned shorting out the white wire going to the switch did nothing, and doing a continuety test with the multimeter yielded nothing as well. Thus showing that there must be something wrong with the white wire. I'll trace it down as soon as I get the chance (and the weather gets a bit warmer. I hate fiddling around the engine compartment when it's below freezing outside)

Now, about replacing the shot wire. What guage wire should I use? The green wire going to the relay is quite thick, unlike the white wire coming from switch which is really thin. What do you think?

Thanks

87_LG4

I figured out why the fan wouldn't start. Turns out that when I put the engine back in after rebuilding it I mixed up the cooling fan temp switch wire with the knock sensor wire. But seriously, that is a major design flaw right there. About the only two connectors that are indistinguishable are also located a few inches from each other. Also, none of the wires had the color they were supposed to have. One was black and the other was white. Not dark green as all the wiring charts claimed.

On the other side, this raises another question. How come I've been able to drive around with my knock sensor module connected to the temp swithc without noticing any effects from it. I'm not entirely sure how the knock sensor outputs its signals, but it stands to reason that when the cooling switch reached operating temperatures that my timing would be retarded, doesn't it? Or at lest be affected in some way or another. But no, not a single code has been thrown.

Any thoughts?

camaronewbie

Remember the Tootsie Pop commercial with the owl? "How many licks ..."

At the end, the narrator states a life lesson: "The world may never know"

At least you got it back right now!