cheme3093

Hi all, I'm new to the forum and Corvette owning. I just bought a 1995 that runs and drives good but I do have some issues left from the previous owner.

I bought the car and it has been modified with two toggle switches to power the cooling fans. It's a total hackjob that I'll have to undo. At first I thought there might have been a problem with a temp sensor or fan relay and the guy didn't know how to fix it but now I'm wondering if all that stuff might be ok because both my analog and digital temp gauges work fine. This car came from California, is this a modification that someone would do without having a problem?

I did notice the sensor on the passenger side head between the last two spark plugs doesn't have wires coming from it. Is that a temp sensor? It looks like they broke off and somebody maybe hid the wires back in a harness somewhere because I don't see anything hanging.

The other issue is I have an unfixable flat on the rear. I'm going to buy two new tires for the rear. The guy has 275/40/17s all the way around the car. I believe it is supposed to have 285/40ZR17s on the rear and 255/45ZR17s on the front. Should I put the stock size back on the rear since that's what is supposed to be on there? Would someone have put the same tire size all the way around for a performance mod of some kind? I'm wondering if I have the correct wheels on the car, they look factory but I understand the rear wheels are supposed to be wider, is there a way I can check the wheels without removing the tires from them to see if they are correct?

I'm wondering if the previous owner did some kind of racing.

Any thoughts?

vetteoz

A not uncommon mod
275's on 9.5" rims all round was std 89 -92.
On 93 - 96 base models 255's on 8.5" rims were used to prevent the fronts tracking in road ruts so check the rim width on the front before going to the narrower tire.
http://forums.corvetteforum.com/1557343127-post3.html

All the cars with perf handling options (Z51 / ZO7 ) got 275's on 9.5" rims all round

Many like having the same size all round because it means you can rotate the tires for max wear

Rim width (9.5 or 8.5 ) is stamped on rear of the rim

vetteoz

Possibly ,because many new owners don't like having the Pri fan run at the factory set 228F ON temp
They don't understand that late model engines are designed to run hotter than old skool SBC's or that you can get the PCM reprogrammed
to turn the fans on at a lower temp without the shade tree mods

Sensor for the analog gauge , digital gauge gets it's signal from the CTS (coolant temp sensor ) on the water pump via the PCM ( which uses that temp indication for the engine operation )

navy_vette

It happens. I had a....I guess....minor fire. Now, my fans run on relays activated by "key on". They run all the time when the car is on. This person probably was just too lazy to fix it properly or do even a half decent replacement. The problem I see with this is that you probably have straight 12v running thru those switches at a pretty decent amperage. One is supposed to use a relay to keep that power away from the driver because it could short out because the switch is not supposed to handle that much voltage or may even hurt someone. I would either fix correctly ASAP or use the existing wiring to do the same thing, but with a relay. It's safer.

Vetteoz is correct. These later model motors run hot. They also get up to temp quickly.

But yes, it's the temp sensor. It's only for the gauge. Mine is a single wire and it is junk. I still have to put the new one in, but I have to come up with a better reason to drain the coolant and replace it. It won't effect the engine operation, but you have no idea what the engine temp is.


If I am not mistaken, those should be the stock wheels and tires. I replaced mine with a full set of C6 wheels and BF Goodrich tires that I got for $500 total that are 265 in front and 285 in back. They were cheap and they help keep that rear end from sliding out.

Do you have a picture of the car? Sharing is caring!
Also, take some pics of the problems so we can get eyes on it.

vetteoz

Could be as simple as the relay (s) being grounded; that would make the fan run ; key on

As noted above
base 93 + cars had 8.5" rims on the front with 255's .
9.5" on rear with 285's

8valve

I just went thru this issue of both fans running with key on. This also was on my 95 that I just bought.

Here is a link to my post and what I found/fixed with pictures.

http://forums.corvetteforum.com/c4-t...s-not-run.html

8Valve

pcolt94

Some people want to run the fans to cool the engine after a race. I can't comment on the correct wiring to make the fans run (but can show you how to do it properly). This practice is not uncommon.


However this is the way the system should operate and you can do these checks.

Turn both switches to the off position. The fans run together in either hi or low speed (on the 95 & 96). Fans should come on in low speed when the A/C is turned on, or when the engine reaches 228*.

The fans go to high speed function when the engine temperature gets to 239*.

If the cooling system is operating normally and while driving the system will usually not reach 239*. If idling the temperature will rise but usually the low speed will keep the temp in check. However depending on outside temperature (95+) and road temperature it can definitely elevate the temperature upwards and could reach the 239* point.

If the system operates properly and your happy, then if you wish you can remove the switches.

Personally I have a switch on my 94 where the fans operate in a different configuration. However I like to turn the fan on if I see the temps going up before they get to hot. It's a personal choice and depends where you live as to what you ambient temperatures are during the year. In Orlando in cooks.

ch@0s

If the wirring was done correctly the switches should not effect fan operation. A lot of owners have either programmed the fans to come on earlier or added a switch. Its very common and nothing to be alarmed about.

I would ck to make sure the fans come on when they should, if they do, no worries.

cheme3093

Thanks for your help everybody. Here are pics of my new car. My friend took these when I was picking the car up.

http://s1286.photobucket.com/user/ch...tml?state=copy

http://s1286.photobucket.com/user/ch...tml?sort=3&o=1

http://s1286.photobucket.com/user/ch...f99dd.jpg.html

Here is the hack wiring job. He came off the fuse block under the hood. Yes, my inner fender well on the drivers side is wrecked too, if anybody knows where I can get a used one let me know. I just need the front and middle pieces. I'm assuming I can pick them off any C4?

http://s1286.photobucket.com/user/ch...755a5.jpg.html

Here is what they did. They cut the harness and spliced directly to the fans with the power from the switches. No hi/low speed only high and they only come on if I hit the switches. I need to get this set up properly so they come on by themselves, I already had a close call with overheating.

http://s1286.photobucket.com/user/ch...1a1db.jpg.html

I suppose I can start by splicing the harness back together, run the tests and see what happens then take it from there with troubleshooting if need be. I would think if the gauge is working then that temp sensor on the water pump would not be the problem if there is one.

Oh yeah, the wheels are 8.5 on the front and 9.5 on the rear. Thanks for the tip on the stamp on the rear of the wheel!

cheme3093

Oh yeah, I only paid $4600 for the car and it has 162K miles on it. I think I got a good deal since it runs great and drives so nice. I just did a brake job on it today, put greenstuff pads on and found out I had some performance slotted/dimple drilled rotors on there; 12" in rear and 13" in front. Can't wait to take it out tomorrow and break in the pads! I hope I find more performance mods, that would really sweeten the deal.

8valve

If it was mine, the first thing I woudl do is get the wiring back to OEM. Match color for color, solder and heat shrink all connections. Then when you know the wiring is back to original, I would follow the FSM trouble shooting for the fans and anything else that does not work right.

You really cant use the FSM trouble shooting if the wiring is not original.

8Valve

pcolt94

This is a start to the wiring. I know its a 96 but should be the same.

I also have another picture of how to properly connect a switch to make the fans go to high speed if you want it (works great).

cheme3093

8valve, I agree and the solder/heatshrink is the way to go.

Pcolt94, thanks for the diagram. I will need that if I have trouble since I don't have a FSM yet. I don't think I'll need the info to make the fans go to high at this time but if need changes I'll send you a PM.

8valve

[QUOTE=pcolt94;1584218905]This is a start to the wiring. I know its a 96 but should be the same.

I also have another picture of how to properly connect a switch to make the fans go to high speed if you want it (works great).

Please post your fan high speed switch mod. Never know when/if you would like to command fans on high

8Valve

cheme3093

Yeah, on second thought that high speed mod sounds like a good idea since I already have toggle switches mounted behind the steering wheel. Pcolt, post that baby!

pcolt94

Its a different diagram (made this couple years ago) but electrically the same, just more stuff on it. I drew in the lines for the wires and connection points and switch connections. You need to use a DPDT switch. Only 4 terminals of the switch are used (center pair and either end pair). This is because both connections have to be made at the same time. (A DPST switch can be used but they are hard to fine, just saying).



Let me know if you can't read it.

cheme3093

Thanks pcolt94. I will save that for future reference.

I reconnected the factory harness with solder and heatshrink today and to my amazement the fans kicked on just as they were supposed to! The mod to run the fans on high would be a piece of cake since I already have the switches and old wiring in the car from the old mod. My guess is that the toggle switches I have are spst though but that won't matter since I have two of them.

8valve

Congratulations....you did well, nice job. As I posted earlier, same thing with mine. Once I cleaned up the wiring, all was well. Why dont people stop mess'n with the wiring, all the problems they create, that we have to straighten out.

8Valve

pcolt94

Slock or Rub Goldberg takes over.
It's a lack of knowledge or talent and the wanting to do it the right way. Nobody knows it all and there is always first time for doing things. It requires an effort to do the research to come up on the knowledge curve to approach a job in a efficient and professional way. Some don’t want to do it or think they don’t have, or think they know more than they do. It's an attitude.

8valve

I agree. And when they get the car all screwed up, especially wiring, no one will work on it to fix it. Then they sell the car.

8Valve