Hey guys, this is kind of an issue because I need my car put back together for work Monday Morning.

I am chasing a fan issue. I bought a new coolant temp sensor and just tried to install it. I ran into a problem, the wiring pigtail does not match!

I'm attaching a picture of both sensors side by side. The one out of my car is on the left, the one I purchased is on the right. Everything I see online points toward the new sensor being the correct one. What is the deal with this rectangular sensor?

The car is an '86 Z28 with a TPI 305.

 

My local O'reilly's says the part number that includes the pigtail is a special order that would take 5 days to get here. I called an Autozone and they have it in stock, I'm going to go pick it up and just replace the pigtail.

Did they supersede the square plug sensor with the oval type, or did someone just splice this other plug/sensor into my harness?

 

The one on the right is for an earlier model, the one on the left the later models. My 84 has the one on the right, so they changed it after the 84 or 85 model year then. Sorry I can't be of more help. Have you tried NAPA?

 

Thats strange if its true, my 86 has the one on the left like I stated above. I called around and the only style I could find was the round one. Autozone had one in stock with the connector, so I'm about to go out and get it installed now.

 

If they have both parts, that's what I'd do, just make sure the one you pull off originally has only one wire and not two, that could be the only issue I see.

 

I believe they all have 2 wires don't they (temp SENSOR)? The 1 wire would be for the coolant gauge sender if I'm not mistaken?

 

Are you talking the one in the thermostat housing or one of the ones in the head? The ones in the head only have one wire going to each of them. The one in the thermostat housing has two wires on it.

Never mind, I was thinking of the Fan switch sensor. That's the one in the Thermostat housing. And I have the one on the right. My bad man. lol ANd yes, it has a two wire plug on it.

 

Wow. I just went out to get that sensor installed and discovered something. the coolant temp sensor in my car was BESIDE the one that I pulled out, to the right of it actually. And, it HAS the correct oval plug/pigtail on it.

So now my question is what did I actually pull from the intake? the diameter of the protruding part of the sensor is a smaller diameter than the coolant temp sensor. What is this thing? The rectangular harness connector wasn't even plugged into it, I assumed that was why my fan wouldn't kick on.

 

Turns out its the cold start sensor. Damn, thought I was on to something when I found it unplugged.

 

Yeah, the fan switch is on the passenger side head between cylinders 4 and 6. I'd check there, Could be the plug melted from header heat, the plug is bad, the wire came disconnected, bad fan relay, bad fan motor...any number of things. The temp gauge plug is on the drivers side head between cylinders 1 and 3.

 

The fan switch is the last thing I think I could replace. The car has a toggle switch wired to the fan, so I know the fan is good. I had a bad radiator hose that I just replaced tonight, a new thermostat, and I put a new relay on as well. I just finished installing my new sensors back in the intake. I need to pour a bit of coolant back in and I'll fire her up to see if this fan will spin when the computer thinks it should.

 

Okay, if I'm understanding correctly, single fan cars don't have a fan switch in the passenger head. That was for dual fan cars only. So that's not something I should have to worry about tonight.

 

Well, I went for a drive and allowed the temperature to climb all the way to 240 and the fan never kicked on. I had to flip my toggle because I'm not comfortable letting it go any higher. I'm kind of at a loss now, I guess its time to chase wiring.

 

My car is single fan, has the switch in the passenger side head. Be careful though, if you have a toggle switch installed by the previous owner, it means he was too lazy to fix it right, who knows where/what he did with the original wiring. I'm pretty sure it's a green colored wire that goes down to it. He may have plugged it, or maybe i'ts just dangling there...or he pulled it up and moved the wire somewhere and tied it back...it really could be anywhere.

 

Thanks, I'm going to take a better look. I'm pretty sure I don't see anything, but between the manifold and the air tube its a little tight. Having that switch would force the fan on at 240 degrees, right? How would I troubleshoot the system's normal operation since I've basically replaced every other component?

 

OOPS

 

Here's something from the technical articles section explaing how thw fan and wiring should be . Hope it is helpful
https://www.thirdgen.org/electric_co...pec_mod_single