VOM-and TPS ohmage measuring question.....
question... at 200ohm range on my multimeter, i get .4 ohms measurement when i touch the leads together for a continuity check....does this rule out the instrument for making accurate assessments?
i measured my TPS as having 1427 ohms on a 2000 ohm scale. the bentley says it should be 1k ohms in the same position. if i multiply out .4 times 1k, it gives me about 1400 ohms, which would make sense. however, when i switch my meter to 20k ohms, and do the wide open test (book says APPROXIMATELY 4K OHMS) the meter reads 3.758 k ohms.
i guess my question is, as bentley says the values are approximately 1k and 4k, is my meter accurate enough to measure the tps, since it says .4 ohms on a continutity test?
Ryan, let's put it simple, as per the BMW drawings ...
TPS in M50 1992 should feed a voltage signal from 0.4 to 4.2 volts to the ECU (DME M3.1).
It is a pot with offset resistors at both ends, so following SSR2 advise, fill in this table:
A= Resistance from 1 to 2 at closed throttle = ??? ohms
B= Resistance from 2 to 3 at closed throttle = ??? ohms
C= Resistance from 1 to 2 at full open throttle = ??? ohms
D= Resistance from 2 to 3 at full open throttle = ??? ohms
then A + B should equals C + D
5 * A/(A+B) should equals about 0.4, and
5 * C/(C+D) should equals about 4.2.
Significant variations would be suspicious, I have no M50 TPS, so cannot give you reference values from my car, may be someone else can. M30 has only contact switches for idle and wide open.
Personally, I find the 1472 value a little bit high, related to 3758, if ECU does not receive top low value, may not realize you are looking for no gas (idle) adjustment through ICV.
You should also verify that you have 5 Vdc at the TPS connector pin 3 when key is at run.
If makes you feel better, yes you should ignore the 0.4 ohm minimum reading of your meter, it is of no significance when you are taking readings in the order of 4K (four orders of magnitude difference).
Javier
OK Ryan, what did you finaly find on your TPS, ...
I'm curious on the resistance values, so to check the BMW drawings are acurate on the 0.4 - 4.2 range.
Did you solve the SRS issue?
Javier