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Overheating and at a loss!

Old 02-23-2019, 05:18 PM
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Question Overheating and at a loss!

I've had this 1995 "Zr28" Camaro for roughly 3 years now, and it's finally giving me a pretty intense issue. This week, it's been overheating pretty bad (max ~200s riding to work and 230 parked). I took it to three separate shops and nobody can read my computer, since they don't have the correct ODB device. After a thermostat and fan relay change, the diagnosis is that the fans won't spin up, even when the computer is telling it to. I've done voltage checks and even bypassing the relay with wires didn't do the trick. I'm trying my best not to go get a full rewiring done, even though there is one wire that burned itself apart. Tried to patch that wire and it burns up again and again, so this is where I'm stuck. Is the wire the cause of my overheating problem?
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Old 02-23-2019, 09:23 PM
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Re: Overheating and at a loss!

Did you check the fusible link in the red wire from the red plastic “+” box near the battery, that supplies power to the fans? See the “late production” 3-relay schematic (courtesy of Shoebox):

http://shbox.com/1/fan_schematic_1995.jpg

Do you have 12-volts constant (key on and off) on the red wire/circuit 402 at pins D1 and F4?

Best way to access the PCM, read codes, read sensors and PCM parameters is Scan9495, free scanning software. Link to download here:

https://www.camaroz28.com/forums/com...95-lt1-874306/

You need to make or buy the correct 16-pin cable for your 1995. The author of the software (GaryDoug) is a Member here, and can answer question on the install, etc.
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Old 02-24-2019, 07:22 AM
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Re: Overheating and at a loss!

I’d consider the burning wire to be a symptom, not a cause. Seems like there’s a short through it.

What’s a ZR28? (EDIT: googled it. An upgrade package once offered by LG Motorsports. Not significant; the car is a Z28 for our purposes.)

Last edited by JakeRobb; 02-24-2019 at 07:28 AM.
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Old 02-24-2019, 02:32 PM
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Re: Overheating and at a loss!

Originally Posted by LawlessZr28 View Post
I'm trying my best not to go get a full rewiring done, even though there is one wire that burned itself apart. Tried to patch that wire and it burns up again and again, so this is where I'm stuck. Is the wire the cause of my overheating problem?
You don't mention which wire is burnt in two. This could help identify where the problem is at. If one of the motors shorted to ground internally or was locked up, I would think it could be possible that the amperage draw could increase high enough to burn a wire in two before the fusible link would. Check the motors for operation by providing a temporary power supply at the fans. Also, when you repair the burnt wire, make sure to use the same size wire as the original.
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Old 02-24-2019, 04:09 PM
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Re: Overheating and at a loss!

Doing this test showed that there wasn't a 12v supply reaching the box. Testing D1 gave a floating value of about 0.3 volts. After a continuity test between the split wire (past the red '+' box) it was connected to the D1 pin on my fan relay plug. I'll post pictures of the wire in another post. (Edit: The relay pin D3 has the 12v. Also the F labeled relay welded itself to the box and I cant remove it. What does this mean?)

Last edited by LawlessZr28; 02-24-2019 at 04:49 PM.
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Old 02-24-2019, 04:11 PM
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Re: Overheating and at a loss!

Here is a picture of that split wire. The box is getting 12V, but this wire burns up every time it is patched even with the same gauge of wire.
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Old 02-24-2019, 08:46 PM
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Re: Overheating and at a loss!

Originally Posted by LawlessZr28 View Post
Doing this test showed that there wasn't a 12v supply reaching the box. Testing D1 gave a floating value of about 0.3 volts. After a continuity test between the split wire (past the red '+' box) it was connected to the D1 pin on my fan relay plug. I'll post pictures of the wire in another post. (Edit: The relay pin D3 has the 12v. Also the F labeled relay welded itself to the box and I cant remove it. What does this mean?)
The fact that relay welded itself to the box is a sign of a direct short. Sounds like power from wire #402 terminal F4 in relay #2 has come in contact with a ground source. You're going to need to remove the relay, see if you can find where it shorted, how much damage was done and if it can be repaired. Almost sounds like the wire that burnt in two was the fusible link.
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Old 02-25-2019, 09:33 AM
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Re: Overheating and at a loss!

The photo shows it’s the fusible link, or someone substituted a piece of wire for the link.

Last edited by Injuneer; 02-26-2019 at 11:00 AM.
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Old 02-25-2019, 09:10 PM
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Re: Overheating and at a loss!

Don't replace the link with a piece of wire that is the same size, Get a new link. The link will have a smaller size wire inside to prevent the type of damage you are seeing. Of course the new link will open with the short that is obviously present. So you have to find and fix that first.
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