Utilizing UT33D Digital Meter for Car Sensor Resistance Measurement

Hello,

I use a digital meter sporadically and have a question about measuring resistance. I will write right away that I searched google and did not find the answer to my problem (it probably is there somewhere, but I haven't found it).

I will have to measure the resistance in the car (some sensor and then the connections between the computer controlling the operation of the TCM automatic transmission and the contacts of this sensor, all in order to eliminate or confirm the failure in this circuit).

Well, I am getting to the point. When trying to measure the resistance of various conductors, I encounter a problem that at different ranges (200 ?, 2000 ?, 20 k?, 200 k?, 20 M?, 200 M? I get completely different readings, not adequate to the range. At least I think so. I have a meter with the symbol UT33D ( link to the manual ).

It seems to me that when the resistance is in the order of a given range, I set and measure this range, but when it is in two ranges (e.g. I expect 50 k?, then the result should be with greater or lesser accuracy in the range of 20 k? and 200 k? . Do I misunderstand something or have I mixed up something or what?

Besides, when I measure the resistance in the range of e.g. 200 k?, I understand it so that the result is in k?, right?

In fact, I haven't done any specific measurement yet (I've been measuring some metal parts, water, oranges - I don't know if these are appropriate examples). The measurement of the element that I am supposed to measure should be in the range of 400-600 ?. According to me, I should set the knob to the 200 ? or 2000 ? position, right?

When measuring the range of 400-600 ?, you need to set the meter to 2000 ? or rather 2k? because this is the case in the meters.
In measurements, a blind range is often selected, when no reading is displayed, you need to switch to a lower or higher range.
If the read value is preceded by a dot, then the range is reduced.

The values given on the meter range switch are the values of the MAXIMUM indication on the given range, i.e. the selected range cannot be smaller than the measured resistance. To obtain the highest accuracy of the indication, select the lowest possible range covering the given measured resistance (if we do not know approximately the resistance value, we set it to the lowest range and check if the meter displays a value different from the symbol of the range overflow, if not, we increase the range until the indication < - this applies to resistance measurement, for voltage and current measurements we start from the highest range).

For example:

Rx?50k? -> set the range of 200k?

Rx?150? -> set the range of 200?

Rx?400-600? -> set the range of 2k?

Note: the measured elements must not be under any voltage because the indication will be incorrect (the meter itself supplies the tested circuit and it must be the only current source in the circuit).

The resistance test should be carried out for both polarizations (the meter terminals are replaced with places) to determine whether we are dealing with a pure resistance circuit (the indications for both connections should be very similar) or, for example, the circuit has directional properties (diode, although this effect is obtained) : a physical element or the straightening properties of a given contact of elements).

The measured element should be disconnected from the rest of the circuit (at least on one side) to be sure that it is measured and not the resultant resistance resulting from the series, parallel or mixed connection of the resistance of the element we want to measure and other circuit elements that we know nothing about. (value or method of inclusion in relation to this subject).

Measurement by measuring the resistance of a liquid, the indication will depend on the surface of the terminals in contact with it (i.e. their immersion depth).

When measuring acidic liquids (e.g. orange juice) or alkaline liquids, it should be taken into account that the measuring tips and the liquid will form a simple electric cell, the polarity and voltage of which will depend on the chemical composition of the coating of the measuring tips and the composition of the liquid. This will result in a false reading.
At higher concentrations, damage to the coating and even the entire tips must be taken into account, so such experiments should be avoided.