so, my other thread is escalated again and we are digressed (and the original problem, fan level 1, is solved). Moreover, to my horror, I have found that after 7 years of experience, there are still a number of knowledge gaps and many things are still unclear. One is the one mentioned in the subject. So on to new knowledge
Now today I found out this, resp. better put, I guess.
1) The two probes on the head at the front and on the water cooler are identical (known) and have a completely different characteristic than the G62 (Motronic sensor) on the rear side of the head. These are NTCs which are designed to deliver 360 ohms of resistance at 22°C and 70 ohms of resistance at 130°C.
2) The AI is smarter than you think. It has an internal fault memory and notices line interruptions AND short circuits (=0Ohm). In the case of a plugged head sensor, the cooler sensor and in the reverse case the head sensor are used as the sole value. The temperatures of both probes are, and this is surprising, not just averaged. There must be more logic in this. I found out that this is not averaged by displaying 95°C, although only the upper one indicates that. But if the lower one is stuck, but the upper one is not, then what the lower one measures is very well displayed, namely 70°C. More on that below. AND: HOW do you read the station wagon??
3) MEASUREMENT: In the case of the pull-off or short-circuit of both probes, the instrument cluster assumes a default value of 110°C. Ergo goes the fan into the 3. Step. This is a protective function that makes sense. The reason for this assumption is that the instrument cluster in both cases (0 ohms by wire bridge or infinite resistance by plugging off) indicates 110°C, but only if this happens with both probes. If one is plugged in, the same measures will be displayed.
4) ONLY about the insertion of the addressed e.g. 100 Ohm resistors you will find the needle also beyond these 110°C. I haven't checked that yet, but it seems logical.
So, and now to my problems that I still have:
1) My cooler drain and the probe near it (hose from the cooler down to the thermostat) remains at 70°-75°C, although I have 95°C above. I measured this with the ohmmeter AND with an infrared thermometer. You can also feel it on the slimes (sleeps on top of the heads hot, hose for thermostating only very warm).
2) My station wagon obviously does not lie, otherwise at least fan level 1 would have been connected (e.g. Only 95°C is indicated, but actually 105°C is attached). The relays are tested, the fan levels also run when the temperature is really high.
3) The probes both measure what is really thing, just checked with IR thermometers. BUT why is my cooler down much cooler than above? Options:
- My cooler is just great (supporting thesis below), but it's not new
- My thermostat is gone (it is brand new AND speaks against my engine holding the 95°C ice, no matter how cold or warm it is outside)
- My cooler is gone (speaks against the thesis below)
Thesis: If my cooler were really added, I think the temperature would rise well above 95°C. But it does not (at least not according to the measurements). The machine also cools down again (if e.g. the engine was switched off and the engine temperature increased to 105°C due to the storage heat, which occurs - in a moment it is again 95°C).
Only: Why 95°C and not 90°C? And why so stable?
Now it's your turn!
IG
Bastian
