I have designed and constructed a temperature monitoring system for my 1985 300D turbo. It uses a Dallas Semiconductor 1-wire network. and 4 DS18B20's digital temperature sensors. There are 2 sensors mounted under the hood. One measures the coolant temperature at the inlet to the radiator, the other is mounted to one of the cooling refrigerated lines to keep a check on the AC. I also have an outside air temperature sensor and an inside air temperature sensor. T he inside sensor is located inside that foam tube where the ACC temperature sensor lives. The DS 18B20's all talk to a Basic stamp BS2-P single chip computer. It drives an 4 line by 20 character line LCD display. The basic stamp is mounted inside the unused ashtray, power is picked up from the connections for the lighter. The LCD display is mounted on the front of the ashtray. If your interested I can send you a couple of PIX . The system has been in use for about 5 months. I built it to try and figure out if the temp sensor on the dash was lying to me or the car actually runs hot. The car seems to run 20 C ( 95 to 100 c) hotter than it should. I have flushed the system, checked for leaks, replaced the radiator cap, changed the thermostat and engine block temp sensor. I belive I probably have a partially clogged 20 year old radiator. Warmer weather will help sort this out.
I posted a message on another reflector site about this thing and I have had 6 requests in 2 hours about it. I plan to post information and pictures of to the other site. Is there interest from any of the Mercedesshop.com group in receiving the information and pictures. ?
I also have a GPS based speedometer using the same stamp technology. The speedo reads speed in MPH with 0.1 Mph resoultion and current heading. When you sit stopped for > 45 seconds it switches to a digital clock until you start to move again.
Thanks
Russ