5kcstq

My understanding is that the flashing coolant warning light in the autocheck system can only be caused by two things, the overheat signal from the MFTS, or the expansion tank low coolant sensor.

So, why does the flashing coolant warning light not stop when I disconnect BOTH of those?

Oh yeah, it's an '88 5kcstq.

moving violation

is it your washer fluid warning light?

5kcstq

<ul><li><a href="http://www.sjmautotechnik.com/TROUBLE_SHOOTING/warning_light.htm">SJM's Warning Light Key</a></li></ul>

5kcstq

dang. i checked it and it's the coolant warning. any other ideas?

comp_jas

I agree with you. No reason I can see. Must be a low resistance in the wiring or defective auto check box.
Any coolant leaking thru the sensors? Might have caused the problem.

bowlerm

did you turn the engine off when you disconected the mfts? my 87 5ks had a bad mfts and when the light came on, disconnecting would not turn it off. if I pulled the plug before starting the car then the light did not come on. I think that once the system gets the signal to turn on it will not turn off until the ignition is turned off.

moving violation

The positive that isn't needed may have shorted or be causing a problem. Just a guess......

5kcstq

and it started flashing as usual. I don't wanna go digging for MFTS sensor or expansion tank plugs while the motors running! =)

My next thing to do is to check for signal wires shorted to ground in the harness. Oh, joy!