Over the past week I have been having a hair pulling issue with my car. 1993 touring automatic. The problem is my coolant buzzer is crying wolf. Every time I drive the car the coolant buzzer is going off and driving me to a headache. The weird thing is, the car is completely full on coolant. Not so much as a drop missing. I have burped, checked, checked, and checked again every time the car cools off and the level of coolant never falls the slightest bit below full. My first question is, where in the world is the coolant level sensor located, and second is there something really obvious i'm missing. I searched a few times and most of the stuff I turned up with was for a second gen. I read somewhere that the lead connecting the sensor to the engine harness is somewhere in the area of the spark plug wires and spark plugs. I even read my downloaded wiring manual and maintnence manual and never found anything involving the coolant warning system. I never saw such a connection and I'm about to perform surgery on the buzzer/flasher unit under the dash to remove the buzzer until I can find a solution. If the sensor is an easy and painless remove and install I will GLADLY buy a new sensor just so I can get the darn thing to shut up. I watch both my temperature gauges like a hawk so if it starts to overheat i will catch it but i really wish I could leave the buzzer alone. Any input would be greatly appreciated.

Matt

 

Perhaps the wiring on the sensor is broke or making a bad connection?
Its the sensor just below the filler I think.

 

The sensor isn't too expensive to replace. I replaced one because it had a pinhole in it and I had a steady high pressure stream of coolant shoot out when the engine was on. It just takes a wrench and undo the quick disconnect. Right on the thermostat housing.

 

I had the same problem. Could be one (or a combo) of a few things (they're all kind of related):

Sensor
Wiring (shorts, breaks, and that's always fun to diagnose )
Connectivity (loose plugs, bad connection, dirt in connector, etc.)

I had the same problem in my car and the issue turned out to be some goofball **** in the gauge cluster. YOu may want to read the following:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/found-reason-coolant-buzzer-even-new-sensor-230805/
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/coolant-buzzing-need-silence-528019/
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/where-am-i-going-wrong-coolant-buzzer-wont-go-off-527235/
Pages a-11 & c2-22 of the 1993 FSM...

Have fun and don't do anything drastic... I know how aggravating it can be!

 

but there lies the problem. there are two sensors on the thermostat housing. one has a plug that goes directly to a sensor and the sensor is made of brass and the other has a plug that is on a wire about 6 inches away and that sensor appears to be plastic. I would assume since the one sensor is plastic it's purpose is to not ground and that there is a metal probe inside the thermostat housing that will allow the coolant to do the grounding to the engine thus completing the circuit and keeping the buzzer from sounding. If the plastic one is the one in question it is completely submerged in fluid and the buzzer is still pestering the hell out of my ears.

 

Right, so the "coolant level sensor" (most likely) won't be the culprit. Remove the sensor and ground out the connector that goes back to the engine harness (per c2-22 FSM). You may have to wait for 30 seconds or more.... if the buzzing goes away, the sensor is a throw-away. If the buzzer persists... you have greater problems.

 

well, I have one more issue. if the coolant level sensor is on the thermostat housing when why in the flying monkey hell is there a connection for it behind the air conditioning compressor. i know there is one connection just above the sensor right beside the alternator, so what is the significance of another connection.

 

well, if you think you have a break in a wire... the easy choice is to get a time domain reflectometer (a TDR in laymans terms). this will tell you exactly where a break in the wire is. it is often used in aircraft and explosive ordnance disposal units in the military

 

if i think i have a break in a wire i will just pull a new wire. if i were working on a 747 i would get a reflectometer, but a car with an engine harness less than ten feet long the wire will get canned in favor of a new one.

 

Automatics use an extra sensor for the trans, to indicate when it is warmed up. I am not sure which one, but I think the one one the right. It is just a thermalcouple I believe. Mine was broken(the unit split open) and I got a new one, and I can not tell the difference with it.

 

I believe there are two sensors on the back of the thermostat housing. The top one is the coolant temp sensor. I think the one under it is the coolant level sensor.

It might be a good idea to start with a new sensor and see what happens. Don't know if it's easy to change or not.

 

A lot of misinformation here. On the back of the coolant neck, there is 2 sensors, the top is a thermosensor, the bottom is a thermoswitch, and NEITHER is the coolant level sensor. The coolant level sensor is the black plastic plug on the FRONT of the housing, with about a 6 inch lead coming off of it.

 

My question is where are you checking the level when it's cold ? You should be looking in the filler neck next to the air pump, not the recovery tank ! The level sensor is on the front of the thermostat housing and is the one thats sets off the buzeer when it's low. If it was a broken wire it would go off all the time (you can ground it) to silence the buzzer but that leaves you no way to tell whats going on in the system.

 

i always check fluid in the filler neck on the motor. not in the recovery tank. i thought was what that is. I found some electrical tape on the wire going to the sensor that i had previously missed. inside was something any mechanic should dread. there were two wires twisted together and then GLUED together. I soldered this connection and now the jury is out as to whether that fixed it or not since the buzzer likes to come on randomly. if it comes on again i will just punt and buy a new sensor and if that doesn't fix it I will just replace the whole wire. And if that doesn't do it i'm pulling the damn buzzer out.

 

only ecu code i get is the accelerated warmup solenoid which i am pretty sure has been removed. other than that, its just the coolant level buzzer (the one where the really annoying squeal of a buzzer accompanied by a red light on the coolant temperature gauge. i drove it today and had no buzzer but it might have been the fact that i fixed some retard wiring. i guess the previous owner thought super glue conducts electricity.

 

i had a buzzer going off for coolant and it turned out to be the black wire that runs into the big wiring haress had been spliced together at one time and came apart casing the buzzer to go nut.

 

mine doing same thing i gave up and unplugged the body electrical cable. most annoying sound in the world is that stupid buzzor we replaced my sensor and flushed the radiator twice. so mine is something with wiring i guess. and im not gonna pay someone to go through my wiuring as i dont have the money.

 

the water temp sensor shouldnt have anything to do with the buzzer. It prolly a poor connection from the level sensor and the harness, or a bad level sensor. Just check the single wire connector from the level sensor and the sensor itself.