Dan...you say you changed Coolant Temp Sensor Too...did you mean also or temp sensor II?
There are 2 sensors at the thermostat housing; 1 sends temperature info to th e ECU...the other to the gauge.  There is a 3rd sensor on the coolant tank which is a coolant level indicator. It will light when coolant is low but will also send a function check signal to the gauge by flashing the light for a few seconds.

> On Aug 8, 2018, at 4:52 PM, Dan N <dn92610@GMAIL.COM> wrote:
> 
> hi all,
> 
> please help with this issue if you could...
> 
> I bought last year a '91 Syncro tintop, WBX 2.1 engine. When I got it the
> temp. needle sits on the top of the white zone at running temp., rad. fan
> working. I get it home, give it a good tune up and change the coolant temp
> sensor too. Nope... the temp. needle is barely moving, now sits on the
> bottom of the white zone. So I did this:
> 
> - swap a good instrument cluster from a running van
> - test the voltage at the sensor connector --> 10.5V
> - ground the sensor connector --> the needle went to the top, red light
> blinking
> 
> *note: when I turn the key on the red light blinks for a few seconds and
> stop (which is normal as in my other van)*
> 
> put the original instrument  cluster back --> no change
> 
> now I am lost... the blue ribbon is in excellent condition, all the little
> nuts back there are tight.
> 
> errr... what am I missing here?... please help... thanks
> 
> dan