tarheel

1986 LG4/stock with 5 speed.

I replaced fan relay, coolant sensor and fan switch. Purchased new fan motor (old one died).

This car is rarely driven so i leave the negative off the battery. However, now when i connect the neg. the fan begin to spin and continue whether the motor is running or not. Only way to stop the fan is disconnect the neg from the car battery.

I assume i have a constant ground somewhere, but not sure where to look. Also, the A/C or heater has never worked and does not blow period. Fan worked fine until a few weeks ago.

CamaroGuru350

Do you have a dual fan setup? If so... Which fan is running? Get a wiring diagram... Is the fan computer controlled?

tarheel

This engine has a single fan. Searching this site has not led me to this type of problem. Usually, the fan runs when the engine is cranked. My fan starts the moment the battery is connected to the car.

y84pauloflondon

I've done some work myself, (cooling system). I agree with constant ground, but where?.... I don't think its your New coolant sensor, could be a bad or wrong relay(double check that). Or could be your fan switch, either bad switch, wrong type, or the wire for it could have a exposed cut in it! Connect neg bat. wire then disconnect relay, see if it runs? Go from there.

fubar_1179

Is your A/C turned on? If so the fan will run as long as it is.

deadbird

Not if the car is off.


The relay is the only source of power for the fan. The power is always hot. The relay coil is powered by switched ignition and ground is controlled by from A/C or the fan switch.
Unplugging the relay should stop the fan.

Remove the relay and test it with 12v to see if the contacts may be stuck (for some reason). If you hear it clicking, it should be alright. If it doesn't click, the contact may have arced and stuck closed. Sometimes a good whack on a hard surface will free it but, the chance of it sticking again has increased.

The only other thing that comes to mind is the relay may be incorrect for your car and is a SPDT relay (will have 5 terminals). One terminal of the (switched) power side is hot until switched.

Just taking a wild guess.

RiV

When you replaced the fan. Did you wire into the old wires or do somthing different. Recheck. Check the ground wire from the fan with an OHM meter to chasis. Might check the relay base for power to the coil that shoudn't be there with the key off. All else fails and you want a good fix.. then by-pass it all and get a aftermarket adjustable termal temp sw. Set to 190-205degrees or per instructions and wire according to the instructions. You can get one at advance auto or any other parts retailer and they're are realitivly cheap and work entirley as accurate as the OEM system. Just read the instructions and get back to driving. Good luck ps on your A/C... also check your vacuum hoses, they will controll/effect how your ac blows or any air for that matter (hoping your blower mtr isn't shot) If you hear vacuum "swooshing" in and out like your rederecting vauum when you move your ac sliders on teh head unit ect then you probably do just have the ac comperessor plug unhooked from the compressor or the blower mtr really is shot. I'm just throwing those last few things out there. Still the q with improper grounding none the less in any scenario. The relay really is ideal problem. Getting the wrong relay isn't that uncommon with firebirds...or getting the wrong MAF relay for 87-89?

y84pauloflondon

If I were in shoes, I would do exactly what DEADBIRD said to do! The mods I've done to my own car have been done by others, replacing or adding relays is something that someone can easilly mess up and cause problems just like what your fan is doing. Connecting just 1 wire wrong to your relay can cause all this.
p.s. RELAY RELAY RELAY.....Check It......

fubar_1179

Yep, i wasn't thinking :P

tarheel

we may be on to something here...i believe the relay does have 5 terminals. I assumed the last terminal would be unused, but can see how the 'guts' of the relay will be setup for 5 connections.

Also, I have a 86 IROC as a parts car. I pulled its' relay. Same issue. It is a TPI engine/auto with single fan. Cannot remember if it has 4 or 5 terminals though.

I will work on this later this week. I'll report back.

Is there a relay part # I can use to order the correct relay at Advance Auto Parts?

thanks!

tarheel

we may be on to something here...i believe the relay does have 5 terminals. I assumed the last terminal would be unused, but can see how the 'guts' of the relay will be setup for 5 connections.

Also, I have a 86 IROC as a parts car. I pulled its' relay. Same issue. It is a TPI engine/auto with single fan. Cannot remember if it has 4 or 5 terminals though.

I will work on this later this week. I'll report back.

Is there a relay part # I can use to order the correct relay at Advance Auto Parts?

thanks!

taterry

I have a problem similar to yours. With the ignition turned off, engine cold (after sitting all night, for example), if I connect the fan relay both fans turn on. If I disconnect the fan relay (I believe it's the fan relay, on the passenger side fender right by the battery) the fans turn off. So I drive like this, with the fan relay not connected. Probably not good.

My primary fan (1988 5.0 5-speed, driver's side according to another thread...thanks Kruss for clearing this up for me) is always on when ignition is turned on. I don't know if this is a fail-safe measure for a faulty fan relay. Motor never overheats anyways, and temp gauge always just below the line between 220 and 100, I have no idea what temp that line represetns.

My question is, think the fan relay on my car is no good and should be replaced? TIA

deadbird

I've read this a few times and am still apparently too stupid to follow what's going on.

One relay makes both fans run all the time and unpluggin it fixes the problem ?

or

Both fans run, one always, car on or off (so you unplugged the relay), and the other runs after starting the car, regardless of temp or the other fan relay being plugged in ?

tarheel

Well, seems advance auto parts ordered the wrong relay. They ordered a relay with 5 prongs instead of the factory 4 prongs. The extra connection (though unused) must have caused a loop where it was receiving power even when the car was off.
I went back and we looked up the correct relay and this problem solved.

However, i started another thread about my fan now rubs on the fan shroud and causes a fuse to blow. Just another issue!

taterry

Sorry for not explaining well, Deadbird.

Right now, car has been sitting all night and the motor and ambient air temps are cool. I have the relay disconnected. I believe it's the relay, on the passenger side fender right next to the battery.

If I connect the relay both fans will turn on. This why I leave the relay disconnected as both fans will never turn off, they'll just run until I believe the battery is drained.

When I start the motor the fan on the driver's side of the radiator (I believe this is the primary fan) immediately starts running. This is on a cold motor, even if the car has not been started for several weeks. I've never seen the second fan turn on, even when the motor is hot.

Motor never runs hot. The temp gauge needle is always a needle's width below the line that's between 100 and 220. I have no idea what temperature that line represents as it's unmarked. The most I've seen the needle move is maybe two needle widths above the unmarked line (this is at idle), and as soon as the car starts moving again the needle falls back to just below the unmarked line.

deadbird

Don't be. Sometimes the beer makes things harder than needed to understand.

That is very strange. Mainly because the fans have separate relays (power) and the relay coil doesn't receive power until the key is in the 'run' position (FAN fuse 20A).

Even if the relay was stuck, only the one fan (passenger/secondary)should run.


Is this the original wiring or, has it been altered ?

It seems like a problem caused more by someone having messed with the wiring but, I could easily be wrong.



As a guess, it sounds like either your fan switch or, your fan pressure switch (A/C) might be bad/stuck closed. Either of this switches are also tied to the ECM 'fan request' input. If one or the other is grounded, the ECM will will call for the primary fan to turn on (eg: when you turn on the A/C, the fan pressure switch turn on the secondary fan and the ECM calls for the primary fan to run)

I would try unplugging one, or the other (or both) of the switches to see if that changes the (primary) fan running. I don't think it will solve the constant running/ car off issue though.

200°, the first one is really 180. I'm really not sure why the gauge isn't just marked that way.

If the gauge truly showed temperature by the face markings, the 1/4 mark would be 160°. Which, would be impossible for the engine to run at if you have a 195° (stock) thermostat.
It would be strange to see a basic gauge like that have a non linear travel as well.

tarheel

Just wanted to follow up on my ordeal and its closing.

I had multiple problems which kept piling up. A fan motor that blew, a coolant fan relay that died and a fan and shroud which would not spin freely which blew the fan fuse.

here is the solution and may help someone out.

Car: 1986 LG4 with single electrical fan and 5 spd w/ non-working a/c

-- relay died. Make sure you get the correct relay. Look inside and count the male connectors. LG4 had 4 and auto parts store ordered a 5 prong relay. Didn't work, get the correct one.

-- fan rubbed shroud. I had a parts car and tried to piece together the setup. Over time, these fans/shroud/mounts warp together. Trying to piece parts from another car did not align properly. Solution was to go back to all parts from one car (original).

-- with all the new parts and good fuses, i still could not get the fan to spin. Well, after searching through the electrical board here, i educated myself on 'fusible links'. Never even heard of this term before, but it works like a fuse, but is inline and soldered to the wire it's protecting.
When changing the relay, i accidentally grounded the wire and blew (melted) the fusible link on the Red cable that runs to the battery and provides power to the fan relay. The fusible link is close to the relay, but knowing what a burnt one looks like is difficult.
To fix, i simply purchased an inline fuse holder from an auto store and placed a 20 amp fuse in it. Cut the old burnt fusible link out and installed the inline fuse. Problem solved.