Head Temp Gauge

I'm a little puzzle about the wiring of my VDO head temp gauge and wonder if anyone has one and can tell me if I'm doing this right.

The sender is just this wire that comes off the spark plug that somehow splits into a red and a black wire. The gauge has 4 connectors. 2 are for the light. The other is marked ground, and +.

Do I just hook the red from the sender to + and the black from the sender to ground? That doesn't seem to make a whole lot of sense electrically with how other guages work. The wiring diagram that came with this said to do just that, but I don't think it's working because it never comes up off 100 (granted the engine was not under load, but it should have been hotter than 100 degrees.

Any help or education about how all this works would be welcome.

Thanks

Chris

Try
www.vdona.com/Tech%20Support/Automotive/Instructionsheets.htm

All the VDO gauge install instructions are posted there -- good reference.

For the cylinder head temp its

www.vdona.com/Tech%20Support/Automotive/instructionsheetspdffiles/0%20515%20012%20130%20--%20Cylinder%20Head%20Temperature%20Gauge.pdf

Thanks Wolfgang,

That's basically the same instructions I have. Guess I should just trust that it will work and once I get it going the head temp should come up under a load.

we sell more CHT gauges than any other single item, and there have been many questions about correct installation, so we created an article on how we do it:

www.germansupply.com/xcart/customer/home.php?gspage=customer/main/tech/cht/cht_install.tpl

scott lyons

Chris, the way I read it is the way you suggested red>+ Blk>-

BD

just make sure NOT to apply battery voltage to the sender terminals on the gauge or you will kill it instantly. the upper 2 terminals are for the light, the lower 2 for the sender wires.

one more FYI, there have been a rash of gauges recently that have had the wiring harnesses assembled wrong, so you have to reverse the polarity of the sender wires in order to make the gauge work. the symptom is a guage that seems dead. in a 3-4 month period we have had 5 gauges with this issue - all were fixed by simply putting the black sender harness wire on the + gauge terminal and the red on the -. i have spoken to the product manager at VDO and they are aware of the problem. it's certainly off-putting to have a new gauge that is assembled wrong, especially after VDO raised the wholesale cost of the CHT gauge by about 30 bucks!

scott lyons
germansupply.com

Thanks for the update Scott. If my guage still seems dead I will try the reversal.

Yup, I got one of the reverse gauges. Red to -, black to + and bingo, it works.

and what kind of head temp are you getting???????????

I haven't actually gone for a drive yet. Still need to finish wiring and such, alignment, get the steering column fully attached, etc. But I know it works because when I fire the engine up the gauge now show about 150 as opposed to nothing.

When I break it in I'll post some stats on my 2056 TIV.

By the way, sometimes the CHT gauge terminals are switched. I've had that problem twice in the past.
Tony