Just purchased an 89 Jetta N/A have a few questions

[Hiacoboni]

The coolant light is constantly blinking sensor was just replaced and it is full of coolant. Has anyone had this problem?/what was the fix?

Next is the Tach does not workchavent gone through wiring yet but was wondering if anyone had any tips on the problem

Any help would be awesome!

[VWDoc1991]

Does it have coolant sensor in the reservoir tank?

[ORCoaster]

I would test the wires coming off that new switch and see if that is the problem or if it might be wires along the way.  Sometimes I have found that the contacts or wires on the old contacts are not the best and just swapping in a new part still doesn't solve the problem.  Got an Ohm meter handy?

[air-cooled or diesel]

you have one coolant sensor on flange on front of head, one sensor on flange on side of head, make sure are hooked up, i have put new connectors on mine, make sure they dont have a short problem, stock had plastic electrical covers for them. doesnt sound like your problem tho, as i believe the one coming off front of head(flange) is for heat, and you dont indicate a over heating problem.
no, ive found the sensor on top/in reservoir can make light blink, while you have normal heat, and a correct tank level(reservoir). i take my connector off, take some of the good electrical spray(crc i think) and clean up contacts, try that, maybe a bad sensor.

[TylerDurden]

My 86 did the same thing. I eventually soldered in a jumper or two on the flexy circuit board of the cluster. The traces can fatigue and crack, almost invisibly. Often intermittent.

[Hiacoboni]

I also notice after driving and the temp gauge is at normal operating temp when I come to a stop and am sitting holding the clutch in the car will high idle unless I put some load on the engine while holding the brake. Would this be caused from one of the sensors?

[ORCoaster]

What you describe there sounds more like a warm engine not adjusted to proper idle RPM.  Or something not coming back to dead rest on the IP after driving.  Is the accelerator cable well adjusted and properly lubricated with some sort of dry lube?

Any time you have to play the clutch to keep the idle down it is up too high.  I had this happening in my car for a bit and I found it to be the perfect cruise control for the city of Portland.  Made the lights perfect in third gear.  But come to a stop and over rev all the while waiting for the light to change.  I went through all the bolts, cable and linkage and finally it went away.