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Fri Jul 08, 2011 9:43 am

I just hooked up a DD CHT and all I get is an under dash reading. DD says the wires are touching and I did the test in the engine compartment and it says the prob is up front. But I have checked and re checked the wires, Red is on ACC and got a ground of course. I didnt need a $150 dollar thermometer. Any ideas anyone?

Fri Jul 08, 2011 9:51 am

what happens when you unplug the sender. Does the error go away?

Fri Jul 08, 2011 10:27 am

Did you wire the wires red to red, and yellow to yellow?

Fri Jul 08, 2011 11:12 am

Red to red and reversed shows error. No unplugging does nothing. its reading the wire instead of the sender. They are mailing me a new one but the one here I have checked several times. Unplug under the dash and it goes to set mode, hook wires together and its a thermometer in yer dash. I'm out of ideas I hope the new wire works.

Fri Jul 08, 2011 11:18 am

Fat Freddie wrote: Red to red and reversed shows error. No unplugging does nothing. its reading the wire instead of the sender. They are mailing me a new one but the one here I have checked several times. Unplug under the dash and it goes to set mode, hook wires together and its a thermometer in yer dash. I'm out of ideas I hope the new wire works.

The reason I asked was because my DD CHT was doing the same thing the walrus' was on earlier pages in this thread. I had red to red, yellow to yellow. Would only read ambient. Switched the yellow to red, and vice versa, and bam - worked correctly. Did that under the dash. Left red to red and yellow to yellow back at the sensor.

Good luck!

Fri Jul 08, 2011 11:19 am

One thing the guy at DD told me to do is hook the wires together in the compartment. It shows if you have a prob upstream If you are getting an ambient reading like that.

Fri Jul 08, 2011 11:21 am

poptop tom wrote: Fat Freddie wrote: Red to red and reversed shows error. No unplugging does nothing. its reading the wire instead of the sender. They are mailing me a new one but the one here I have checked several times. Unplug under the dash and it goes to set mode, hook wires together and its a thermometer in yer dash. I'm out of ideas I hope the new wire works.

The reason I asked was because my DD CHT was doing the same thing the walrus' was on earlier pages in this thread. I had red to red, yellow to yellow. Would only read ambient. Switched the yellow to red, and vice versa, and bam - worked correctly. Did that under the dash. Left red to red and yellow to yellow back at the sensor.

Good luck!

I'll try it thanks! already did it in the compartment but this gauge is kinda weird, just might work.

Fri Jul 08, 2011 11:31 am

OK I tried that and it went to set mode???? Seems to be a short. Just cant find it.

Fri Jul 08, 2011 11:33 am

Try moving the "+" power to another location on the fuse box.

Fri Jul 08, 2011 11:59 am

I was just gonna try that and it started working! I cant make it stop working now so I guess it didnt have enough data or something. [img][/img]

Wed Oct 12, 2011 8:41 pm

So, I have a VDO gauge setup now, if I just replace my VDO gauge with the DD one will I now have accurate readings or do I need to also change the sensor and the wires from the sensor to the gauge?

Thu Oct 13, 2011 2:19 am

I prefer the DD set up as you can set it to "flash" at a desired temp. I don't watch it all of the time.

You need the correct DD sender and wire. Buy the 18' long one. THe install is as described here....

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

Thu Oct 13, 2011 6:13 am

I guess I'll buy the DD kit and install it next time the engine is out...

Sat Oct 15, 2011 6:52 pm

My heads use a 12mm plug, does anyone know if they sell one in this size? It seems to be 14mm or 1/2 inch ring terminals only?

Mon Apr 09, 2012 8:47 am

Need feedback on possible adaption for DD Ring placement.

The best place to put the DD ring is between the #3 plug and cylinder head.

The problem is the torque tends to disfigure the ring and can create false high readings.

The solution (?) is to cut the ring in half or smaller and gently apply two "spot welds" of JB Weld on either side to hold the ring half in place against the cylinder head. In this fashion you dont worry about smashing the ring as it is not under the plug so no extraneous hot gasses.

What do you think? Thanks.

Jack
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Mon Apr 09, 2012 9:09 am

Here is a picture of the adaption, I hope.

Mon Apr 09, 2012 9:18 am

Is your engine out of the bus?

The best way would be to go this route, if you have the access
to the head to do it this way.
http://www.germansupply.com/xcart/customer/home.php?gspage=customer/main/tech/cht/cht_install_2.tpl

Mon Apr 09, 2012 10:04 am

No, I did that exact procedure when the engine was out this past summer. So actual placement is not the issue, it is torque and crush and disfiguring of the ring that is my concern. With it are abnormally high temps.

I say high because I will see a 400* reading on the gauge and pull the wire to shoot the cylinder head at the plug with a laser temp gauge and it reads 75* or more degrees high. I even tried a different laser to the same result.

This is leading me to the conclusion either the gauge is off or I am getting gas bypass.

Mon Apr 09, 2012 1:13 pm

if your getting false high readings from it not sealing properly you should be able to tell just by looking at the plug.