Low Coolant Light
 

Hey All,
The latest challenge on the 1989 is to determine why the low coolant light comes on often. I have replaced the sensor that is located in the radiator twice. The light intermittently comes on and goes out regardless of speed or weather conditions. The radiator is full. Do ya think that I need to disconnect the battery to reset the computer after replacing the sensor?

Any idea gratefully accepted.

Thanks,

RE: Low Coolant Light
 

Why did ya' replace the sensor twice? Didthey test bad? Or just tryin' the ol' Fully Automatic Assault Wallet practice?[sm=shootshoot.gif][sm=violent053.gif]




If ya' just did a coolant change, ya' can get an air pocket in the system, that occasionally circulates to the sensor. When that happens, the light comes on.

After a few drive cycles, all the air get 'burped' out.

If you haven't had acoolant change (or any loss, which allowed the air in there), somethin' else is wrong... But try to find out what's wrong, instead of buyin' parts blindly. Feel free to send the money to me tho'.:D

RE: Low Coolant Light
 

Actually, this beast has done a major offensive on my wallet! Have been driving it for over a month since the antifreeze was put in. One would think that any air pockets would be purged by now.

Am not sure how to test this sensor. It has only one contact and checking it with a meter does not seem possible. Any ideas on how it should read?

Check is in the mail!

RE: Low Coolant Light
 

1st, check your "Gauges" fuse which powers the "Low Coolant" module. If the fuse is good, then most likely the module is bad. I'll have to get back to you on the location of the module and the wiring colors as there are 4 wires to it. Most likely it is behind the passenger side I/P.

RE: Low Coolant Light
 

Yeah, you'd think, but I'm guessin' NOT. Have you done highway drivin? Maybe an hour sustained? I don't know how long it takes, but I have re-worked an L98 top end, and it is convoluted indeed.

RE: Low Coolant Light
 

Light is still on and seem to stay on longer. Coolant level is good. New sensor did not help. Checked the manual and no mention of any of the relays in the fuse panel controlling the coolant level sensor light. Will have to dig in to the wiring diagram and see whats what.

Thanks,

[Deleted]
 

[Deleted by Admins]

RE: Low Coolant Light
 

Stays on longer could mean the air is comin' up as you do more drive cycles. Put your heat on max too - to flow the coolant more...

Are you checkin' level at the radiator cap, or at the reservoir?

I got haynes diagram, but I think it's for '84 CFI, and doesn't say much.... If ya' want I can post it...

RE: Low Coolant Light
 

Did you read what I had said earlier in the post about the "Low Coolant Module"? It is probably bad or has no power to it. That is what turns the light on based on input from the level sensor.

RE: Low Coolant Light
 

Thanks for the tips.

Have had little time to play with it lately but the light remains on.

Hopefully, when the weekend comes along, I will dive into it.

Drive on!

RE: Low Coolant Light
 

I know this is a old thread but if this problem hasn't bin solved and your corvette is a 86-89 read this a couple of times until this makes sense to you. It does make sense. It is written by Gorden Lillebrew that I am guessing is a GM troubleshooter buy the way it is written. sorry it is long but very Good info here.

The 1986-1989 low coolant light coming on is a common problem. The green wire going into the radiator is normally grounded by coolant touching the probe wire. Usually what happens is when the thermostat opens at 195 degrees, if there is any air in the system the coolant probe becomes ungrounded. This causes the light to come on.
The radiator is actually higher then the engine; therefore, if you take the radiator cap off and the coolant doesn't run out, ( it is just Laval with cap), then you have a 2 inch air pocket across the top of the radiator. When the thermostat opens this air pocket is what makes the coolant light come on. This air pocket is caused by air being taken in to the system on cool down.
After testing in the plant we discovered that the black heater and radiator hose clamps loose torque and allow air to be sucked into the system. This is a sealed system. Any coolant expelled through the radiator cap into the overflow bottle will be sucked back into the radiator on cool down, called purging. To prevent this air being sucked back into the system, do the following.
1. Replace all black hose clamps with shiny stainless steel hose clamps.
2. Put 2 small adjustable stainless steel clamps on the hos of the overflow bottle.
3. Put 2 small adjustable stainless steel on the tip coming out if the radiator going to the overflow bottle.
4. When you fill the radiator with the engine running, in park or neutral, hold the rpms at 1500.
5. When the radiator is full, with the rpms at 1500, put the radiator cap on.
6. Let the engine go back to idle, AC off, when the coolant fan comes on at 228 degrees, shut the engine off and let it set. This will purge any air out of the system and into the overflow bottle.
7. Keep the overflow bottle about half full at all times so no air can be sucked back into the system.
8. When the engine cools down coolant will be sucked back into the engine replacing any air.
9. With a full system and no air, when you take the cap off, col lent should run out because there is no air pocket. Then you will have to purge the system again to get rid of the air pocket you just created when the coolant ran out.

I finding number 9 to be saying you will have to purge every time you open the cap
hope this my help some
Ric w.