walterh

Hey guys, I'm getting ready to buy an 1989 Vert, and the coolant buzzer is going off. Upon inspection, the coolant level sensor wire is connected to the sensor, but not connected to I would guess should be somewhere on the wiring harness. Can someone help me please? I couldn't find any info in the FSM. Pics would be great. Thanks in advance!

Hot_Dog

Maybe the senor is bad? Try grounding the wire. If the buzzer stops, than the sensor is bad.

Relisys190

iTrader: (4)

Either the sensor is bad or your radiator is low exposing the sensor. Ground the plug to the frame and see if the buzzing stops. This will tell if it's connected within the harness.

Properly bleeding the coolant system is key.

walterh

The wire is connected to the sensor on the radiator, where does it go on the wiring harness, or where does the other end connect?

insightful

check the coolant level? that's what the sensor is for.

Hot_Dog

At the moment, I don't have an S5 wiring diagram handy. I do have an S4 wiring diagram that shows that the coolant level sensor wire goes to a coolant level unit and buzzer in the instrument cluster. From there, it goes to a warning light in the idiot light cluster.

Hot_Dog

Checkout the below link, it has S5 wiring diagrams attached for coolant level sensor.

https://www.rx7club.com/2nd-generati...oolant-656767/

walterh

Thanks for the wiring diagram. That's what I needed.

walterh

I still can't find where to attach this wire. Can someone help?

Hot_Dog

The brown wire runs towards the left front (near battery), then into the wiring harness routed on the left inner fender, and eventually to the instrument cluster.

walterh

Could some snap a pic of where on the harness it connects?

walterh

It looks like from the FSM that it connects somewhere on the passenger side.

Hot_Dog

Ok, I looked at my car and the wire is buried under all the ducting and shrouds. Nothing to seen without ripping everything apart. Looking at the wiring diagrams provided by HAILER's in this link (https://www.rx7club.com/2nd-generati...oolant-656767/), it looks like the wire might enter the harness at right front of engine. It might be at the point where the O2 wire exits the harness.

Relisys190

iTrader: (4)

I am now sharing your issue. Had my 1990 GTU out yesterday. All fluids are top leveled off and the buzzer began to sound yesterday. I immediately pulled over and checked for any visible leaks to no avail. I also grounded the sensor plug directly to the frame and the buzzer persisted. So this is telling me there is a break in the wire . I will be pulling the air-box and other items out to trace this issue. let me know what you've found. Thanks, -

M

walterh

I haven't had time to check on this, but I do know the wire connects some where in the harness on the passenger corner behind where the headlight is.

walterh

Here are pics of where the coolant level sensor connects into the wiring harness. Passenger side, under the air box.

Relisys190

iTrader: (4)

Looks like you've found your issue. I think I may have also. Seems even when testing the ground to shut my buzzer up I was not getting decent continuity to ground/silence. My radiator is in fact about a cup empty, enough to upset the sensor. I purchased the coolant filling funnel setup to properly fill and bleed the system this weekend. See how it goes.

-M