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I have a 1987 corvette, and the electric fan that cools the engine isn't kicking on...checked the wires going to the fan and there's no power going to it....so that leads me to believe that it's a bad relay, couldn't find the relay, not sure if there actually is one...what does the relay look like? And also where abouts is it located? Thanks!
 

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I have a 1987 corvette, and the electric fan that cools the engine isn't kicking on...checked the wires going to the fan and there's no power going to it....so that leads me to believe that it's a bad relay, couldn't find the relay, not sure if there actually is one...what does the relay look like? And also where abouts is it located? Thanks!

The fan is operated by a two-terminal switch that is screwed into the right-side cylinder head just above and to the front of #8 spark plug.
 

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Haynes page 3-5 has pictures and info for you. Your fan is powered by a fuseable link thru a relay to the fan motor. The computer and override switch turns on the fan at 239' thru the relay. The fan relay is located next to the brake booster. Get the Haynes manual to troubleshoot the system.........
 

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The fan is operated by a two-terminal switch that is screwed into the right-side cylinder head just above and to the front of #8 spark plug.
On your C3 maybe
86 - 89 as in question here are controlled by the ECM only , from temp input from the CTS located in intake under TB.

84 is only C4 with a temp switch ( a single wire unit ) solely controlling the fan ( and the A/c switch )


 

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The computer and override switch turns on the fan at 239' .
Only in 85

86 - 89 have ECM fan control and main fan also runs when A/c is on ( via pressure switch on A/c line) at any engine temp
Only the B4P Aux fan option has a seperate independent switch in the head

 

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1987 corvette,
..checked the wires going to the fan and there's no power going to it....so that leads me to believe that it's a bad relay,
Disconnect relay and check to see if you have 12V on the red wire into relay connector , key off.If not fusible link is blown.

If you have power , temporarily jumper red to blk/red wire in relay connector and see if fan runs.
See diagram above
If not , faulty wiring to fan or faulty fan motor

If it does , relay or relay control circuit ( relay power or wire to computer ) is faulty

Check for power on blue wire ( key on ) .If not fan fuse in fuse box is blown.
If you have power on blue, jumper the green /wht wire to ground with relay in connector.If fan runs relay is OK .
If not replace relay.
 

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Well, I will bet that 87 has a fan override temp switch and so do the other years. Haynes has the systems broken down 1985-87 with a wiring diagram that I have found to be correct for my 85, and I note that vendors sell replacement fan temp override switches in the oem temp and lower temps for all years.........
 

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with a wiring diagram that I have found to be correct for my 85,....
As I noted above ; a one year freak as far as fan control goes!

Point out the " fan over ride switch" in the circuit diagrams from the FACTORY SERVICE MANUAL I posted.

Haynes has the systems broken down 1985-87 with a wiring diagram that .
Haynes manual are well known for their faults and recommended as toilet paper by most serious C4 owners :toilet:

I note that vendors sell replacement fan temp override switches in the oem temp and lower temps for all years.........
Yes and if you were up to speed you would known they are not OEM replacements ( exp '84 )
but are designed to be spliced into the OEM fan wiring so as to bring fans on earlier while still retaining ECM control should the switch fail.

http://content.mamotorworks.com/pdf/609106.pdf


They only work as direct replacements for the standalone Aux fan switch used on the B4P option ( if fitted )
and the fan switch on '84 models
 

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"Yes and if you were up to speed you would known they are not OEM replacements ( exp '84 )
but are designed to be spliced into the OEM fan wiring so as to bring fans on earlier while still retaining ECM control should the switch fail."

I think that I am up to speed. However, I only have an 85 C4 so I am not an ex spirt on all
c4s. On my 85 I replaced the original over ride switch with a 200/185' switch from Corvette America. What a great sight to watch your temp gauge stop rising at 200' in heavy traffic and then drop back down to the t stat setting, instead of the factory 239' setting. Every C4 owner should put in a lower temp over ride switch. Haynes has a wiring diagram showing proper wiring to do it and pictures of the proper location for those who do not have an oem one..........:thumbsup3:
 

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I only have an 85 C4:
exactly
There a 5 different fan control systems used on the C4's and yours is a one year only so your expertise only relates to a '85 ; irrespective what your erroneous Haynes manual shows
 

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Nothing better than having someone around that has the knowledge base to cover multiple years.

Good info right there vetteoz, thanks for sharing!:patriot:
 

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Nothing better than having someone around that has the knowledge base to cover multiple years.
I'm not into points scoring here.

Just trying to establish that your intimate knowledge of your car ( of which TB is a prime example ) may be irrelevant to the owner of a different year.
All very well to be helpful but if it leads a newbie owner up the garden path in his quest for answers then of no benefit to him.
 

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I'm not into points scoring here.

Just trying to establish that your intimate knowledge of your car ( of which TB is a prime example ) may be irrelevant to the owner of a different year.
All very well to be helpful but if it leads a newbie owner up the garden path in his quest for answers then of no benefit to him.
Good thing you aren't into keeping score because that wasn't the intent of my post. I was merely pointing out that you have GOOD KNOWLEDGE about Corvettes in general and I was THANKING YOU for sharing your information. Your post was very informative and could help several different early model C4 owners - IF they know how to use the search function of course. Ease up Trigger...try to recognize a compliment when you get one. Not everyone on this board is out to disprove you.:thumbsup3:
 

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Ease up Trigger...try to recognize a compliment when you get one.
Much appreciated :thumbsup3:

However you misunderstood.
Point I was making was I was not trying to be a " smart ar*e", just noting that systems vary year to year.
 

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Much appreciated :thumbsup3:

However you misunderstood.
Point I was making was I was not trying to be a " smart ar*e", just noting that systems vary year to year.
Got it!:thumbsup3:

I must admit that it was shocking for me to read how different the systems were from year to year. I wouldn't of guessed or even known. Reading this kind of technical stuff on here is what keeps me coming back. Makes it worthwhile to log in when I can learn something like that.

Thanks again and I apologize for misunderstanding your intent. Although, I would be extremely surprised if anyone felt you were being a smart ar$e...your posts were fact filled and didn't have any "opinions"...just the facts, with diagrams as proof.
 
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