S S0DEN

If I install the 180 T-Stat on my 88 Vette L98, will it mess with any of the sensors? I'd like to have the engine run a cooler, right now it runs between 192-200 degrees.

Thoughts on doing this?

MrWillys

TPI is fully warmed at 170, so a 180 thermostat will work fine. Program the fans at 200 (93C) on, and 190 (88C) off.

S S0DEN

My fans are on all the time, even when I just turn the ignition on and not start the engine.

S S0DEN

I take it the previous owner wired them wrong?

GREGGPENN

Possible though not probable.

I'm thinking the ECM causes the fans to run constantly when in fault mode. I don't know the various faults that would cause it off the top of my head. The ECM itself could be "bad" or have a connector problem. I'd have to consult the manual. Others, more adept at this issue, will likely chime in.

To answer your original question, lowering thermostat temp will not cause fault codes.

S S0DEN

The check engine light has not come on except for when I forgot to plug the Mass Air Flow sensor back in. For the system to be run in fault mode would cause a check engine light correct?

I am thinking the previous owner had a relay issue and just hard wired the damn fans...

GREGGPENN

You make a good point. The only time I've gotten the fans-on condition is while logging (scans). I don't recall a "check-engine" light being present. But, I'm plugged into the ALDL connector. I wonder if it's possible there's a piggy-back (or jumper) in your ALDL connector? This can be used to flash codes to the info center IIRC.

Also, relays are typically used to trigger the high-power supply necessary to drive accessory components. "Hard-wiring" around a relay doesn't make sense either. I also can't understand why anyone would want the fans running 24/7.

WW7

They won't last anywhere near as long having to run constantly.... Get that fixed as soon as you can.....WW

S S0DEN

Yeah, that's my next project this week... I actually thought it was weird the fans ran all the time, but did not pay much attention to it. Of course I have only driven the car a few times to work which is 2 miles down the road.

S S0DEN

After further review:

There are two fans, 1 mounted on the front of the radiator and one mounted behind the radiator.

If I unplug the fan relay, the fan in the engine bay will shut off however the other fan stays running. The instant I plug in the relay, both fans run, non stop.

The check engine is not lit and the engine runs good leading me to think the system is not in limp mode. Any suggestions?

Corvette40

I have an 88 and a 180 thermostat and everything runs fine with no codes.

The main fan is commanded on by the ECM at 228F, and I can't remember at what temp it commands off. When I installed the 180 thermostat my tuner changed the command on to 210 and off at 185.
The aux fan is controlled by a temp switch in the drivers side head.

Both fans are switched on and off through a relay and neither should run at all times. The aux fan brushes wear out quick too. The PO either bypassed the ECM and relays or both relays are stuck closed.

Get the FSM, it has the wiring diagrams.

S S0DEN

Yeah I need to get one, I did not know there was 2 relays, thought both fans ran through the same relay?

MrWillys

1 is primary, and 1 is secondary. Pull the relay next to it and see if the other shuts off.

S S0DEN

Ok, the 2nd relay is located on the radiator housing, unplugged that and it shuts off the other fan. So they are not hard wired...

Chances of both relays being bad? Slim I think. So is it a temp sensor in the head or the ECM causing the fans to run?

MrWillys

The ecm sends a green wire to the primary, and the secondary gets a signal once ac kicks on, and a temp signal I'm unsure of.

S S0DEN

So the secondary for fan #1 is the AC - fan #2 must be the temp sensor between plug 1 and 3 on the head.

So this means the chances of both secondary options being bad is slim and it is more then likely an ECM issue.

I guess my next step is to unplug the battery, plug it back in and have the ECM scanned.

MrWillys

There is no secondary for fan 1. The green wire from the ecm turns it on and off. The secondary can be either temp, or ac

S S0DEN

Odd, were do you think I should start?

S S0DEN

I did find this:

http://www.chiltonlibrary.com/Conten...aspx?ca=Repair

If anyone can read the wiring diagram for a 1988 Corvette L98 lol

84wannabezo6

You might check your a/c there is a switch on my car that turns on the fans whenever the a/c is on