hello
ah.. those values dont make sense but hey, if the gauge worked then cool!!!
Ive had a look at the 343 wiring diagram and one for the post 86 cars.
The difference between the two and why the older cars have two wires is as follows. (I believe and am happy to be corrected!)
On the earlier cars, one lead from the sensor provides the variable resistance to the gauge unit which thus determines the position of the needle on the gauge. When the coolant temp is high enough to need to turn on the coolant warning lamp, on the early cars (two wires) the switch for this lamp is inside the sensor. The switch closes and the second wire provides the ground line for this circuit, thus illuminating the lamp. On the later cars (I guess VDO therefore) the warning lamp is tripped on by the gauge itself only...prob a simple position cause? I dont have a VDO gauge out of cluster to hand at the moment.
Therefore if the Smith two wire sensor has a resistance of 35 to 45 ohms at "operating temp". If the VDO sensor has a resistance of 180 ohms, the gauge will run "hot" with the smiths sender. The warming lamp wont work but really you dont need that as if the needle is heading skyward you wanna stop before the light!! As a respectable car enthusiast, you aint gonna push the temp so high anyway
so, you only need the sensor wire which on the 343 is....Gn = green. the lamp line is yellow. Given the age of the car (and if they are like the 66 I did) they are all yellow by now!!
Im not an electrical engineer but Chris C is so maybe something can be fitted between the sensor and the VDO gauge to get the resistance right.
Im happy to do a resistance Vs temp graph with the Smiths sender for you and then if you do the same with the VDO one, we can see the difference in values and the conversion needed. I presume the senders give a linear output....
thanks for the sender. I hope this helps......
and of course... good luck with the replica build!
