You should try a couple of quick tests first.

First try shorting the 2 pins of the connector after you unplug it from
the sender. Use a straightened paper clip or some such. That should peg
the needle on hot and flash the LED. If it doesn't, then short the paper
clip from the connector pin for the yellow/red wire to bare metal ground
in the engine compartment. If that still does not peg the gauge and
blink the LED there is one last way to eliminate most other
possibilities other than the gauge.

Remove relay "43" from relay socket 3 in the dash relay panel. Run a
wire from pin 4 of the now empty socket to bare metal ground. If this
still does not peg the gauge, the likely problem is a bad gauge or a bad
connection on the 14 pin connector that goes to the back of the
instrument cluster.

Mark

Tim Marciniak wrote:
>
> Regarding my 90 Multivan I'm pretty sure needs a temp gauge.  Any
> body done this job?  About two weeks ago the needle was reading a
> little below its normal position, now it does not register at all
> except that the light blinks on at startup then goes out like normal.
> Test the gauge as close as I could with resistor values for testing I
> got from the archives and nothing moves the needle.  Voltage
> stabilizer is in spec.  No way to test sensor.  Pretty sure its the
> gauge.
>
> Tim
> --