One thing worth checking is the polarity.

IIRC, for some reason, I had to switch the connections at the back of
the VDO gauge. i.e. black to positive. The connector at the engine bay
was on properly, but I still had to reverse the connections at the
VDO.

Remember that there are seperate connections for the sender, and VDO
display light.

Cheers,

Neil.

--
Neil Nicholson. 1981 Air Cooled Westfalia -
"Jaco"  (Bustorius)

http://web.mac.com/tubaneil

Please send fav Vanagon/Westfalia links to me at:
musomuso1963@hotmail.com

On 10/6/07, Jake Beaulieu <jbeaulie@nd.edu> wrote:
> "First according to my infrared therm. the heads near the intake never went
> above about 200 so was that hot enough for the cht to register?  The
> needle on the cht guage didn't move ever.  I hope to drive the van soon,
> at what temp should the guage register?  Are there ways to test the
> guage/sender."
>
> Hey John,
>
> The sender on the CHT gauge generates its own voltage when heated up.  You
> can test to make sure the sender is working by hooking it up to a volt
> meter and then holding the sender ring under a lighter.  You should get a
> measureable voltage.  I have done this, but i don't remember what the
> magnitude of the voltage was, pretty low I think.  If the sender is
> working then connect it to the gauge and again hold the sender under a
> flame.  You should get a reading.  Just don't make the same mistake I did
> and run power to the sender circuit on the back of the gauge.  That fried
> the gauge in short order!
>
> good luck,
> jake
>