Thread: Phantom, intermittent LOW COOLANT LEVEl light, + other fun stuff

Hey y'all

The indespensible GP is at it again...awhile back I posted about some issues that proved to be a crank position sensor gone whacko.

Subsequently and non related, I had to reseal the upper and lower intakes, after the lower was leaking oil like a Detroit Diesel in a shrimp boat, and the upper intake was barfin' the long life coolant.

Back to the issues at hand. Prior to the failure of everything in the cooling system (and it's repair) we had a phantom LOW COOLANT LIGHt that would come on faintly, some times bright, at times just go away. The level was fine, the sensor clean, then replaced. No real change. I found some times if I wiggled the connection it would make a difference, so I got about 6" of the harness and plug at the U pull, and spliced it on. No change.

ALSO- the outside temp has become unreliable. Used to be right on. My question is.....do the sensors use strictly resistance to give information to the PCM, or are they a voltage return type? I am a Cat marine tech, and those engines send 5 volts to each sensor and then base the reading off a return. I ask this as I also took a level sensor from the U pull, put my ohm meter on it, and got a reading some where around 2.5 ohms, then filled the little well with liquid, and there was no change. Did I grab a bum sensor?

NOW, this weekend I took a 600 mile round trip, half 65-75 mph interstate, about 15 percent city, the rest 55-60mph country roads. The car used to get a calculated (fill it up, divide the gallons into the miles) 26-28 mpg in these conditions, now I am down to about 24.2. New plugs, new crank sensor, clean air filter, tire pressure good, no 400#'s of junk in the trunk etc. Over time the mileage is just plain OFF what it used to be. No codes (until 75 miles from home last night) and a recent Magnaflo cat (stocker was coming apart) and new heated O2 sensor. Not driving with a heavy foot. Could the injectors be going tired?

I got a PO404 last night, I just need to find out what that is.

Any thoughts on the coolant level light, the MPG?

3800 series II, '99 GT sedan. Bought her with 62,000 in January of 2005 and now has 201,000. Been a very good car.

I also get the phantom light but it's always full

Well I could unplug it, know that for awhile but that isn't really "fixing" the problem, the previous owner of my wife's '91 Camaro RS took the bulb out of the SES light....moron! Rather than fix a problem, let's just ignore it ......

I like to fix things and it irks me when something does not function, and I don't give up until it works right.

could be the ground goin bad. Take it off and sand the ground itself and the connector.

That is what I thought, where does the ground go back to? I can trace the harness to where it intersects with a larger loom behind the battery.

I see you are from Benson, MN. I grew up near Sauk Centre.