Race Technology

I have a new water temp sensor that I purchased from Race Technology, with the cable (and resistor) attached. It's installed, and I've connected signal and ground to the DL1. However, when I connect the red wire to the 5V ref out on the DL1, the car idle shifts from "normal" to almost a hunting (rpm increase from 800 to 1200, drop back, then repeat, continuously). Disconnect red wire, idle returns to normal.

I've checked the DL1: 5V is supplied correctly, 12V power and ground are good. Other sensors are working correctly. I should note that I have the CAN ECU interface connected and working properly. A Dash2 is also connected and working.

DL1 is a mark 1, serial number 701, firmware 33-4.

I'm at a loss . . .

Everything on the DAQ system should be separate and passive relative to the motor and it's ECU. Good ground on the motor? Honestly sounds like a ground loop, but that would also likely fry the DL1.... (just guessing....)

Thanks, I'll have a look at the total current draw of the sensors and the possible existence of a ground loop.

Interesting. I've got about 2.3 V constant on this wire. How the heck did that happen?

The same voltage is also present on the signal wire, so I'm guessing there's a short between the two.

2.3 vdc is likely a short..... try taking off that pressure sensor...

I am guessing that this sensor is also attached to the ECU. It sounds to me as if the ECU is applying a voltage to the sensor. When you are connecting the sensor to the DL1 it is applying a different voltage to the sensor which is causing the ECU to misread the temperature and so it runs roughly.

You will be able to use the sensor by just reading the voltage on the sensor as it is, but you will have do your own calibration on it to sort out which voltage corresponds with which temperature.

Dr. Hill wins the prize! I took a look at the sensor and sure enough it's connected to both the DL1 and the ECU. Not what I had intended, but broken telephone works with mechanics too . . .