Sensor Test Readings

[JMI]

M30 - 1989 535i

Troubleshooting an idle problem

There are two sensors on the outlet from engine block:

http://www.realoem.com/bmw/showparts...18&hg=11&fg=35

Bentleys is somewhat unclear to me. I get the following resistences:

#12 = 5220 ohms
#14 = 2135 ohms - on my engine this one has the "blue" connector(?)

Do these readings look right?

TIA

Jim

[winfred]

one is for the gauge and the other is for the computer, i can't remember at the moment which one is the computer, the #s look normal, usually when one of those sensors craps it goes way off

[winfred]

make sure that the tps is going into the closed position, if it's not telling the computer the throttle is closed the computer will not turn on the idle circuit

[JMI]

make sure that the tps is going into the closed position, if it's not telling the computer the throttle is closed the computer will not turn on the idle circuit

The Throttle Position Switch checks out.

I'm out of time for today. Will look at the fuel system at a later time

Thanks

[JMI]

Does anybody else have any knowledge of the correct resistance of #12

#12 = 5220 ohms

and if that is the sensor for the computer?

TIA

Jim

[bill g]

I have same year and model (Australian delivery). All I can tell you is the sensor with blue plug is for the ECU (computer), other one is temp gauge sensor.
My ECU coolant temp sensor tested as follows -
3710 ohms cold, 330 ohms engine fully warm.
It seems to be working OK and is within specifications stated in Bentley workshop manual - you should get a copy.
Cold resistance can vary quite a bit depending on ambient temperature. On extremely cold day the resistance can be about 7000 ohms or more.

Bill G

[genphreak]

M30 - 1989 535i Bentleys is somewhat unclear to me. I get the following resistences:
#12 = 5220 ohms
#14 = 2135 ohms - on my engine this one has the "blue" connector(?)
Do these readings look right? TIA Jim

Measurements in the Bently suggest that your 2135kOhm reading (if the sensor is good) was done at around 20 degrees C/68F. What was the ambient when you did it, and was the engine at ambient temperature?

There are no measurements in the Bently that describe what the black plug should read but it only affects the needle, so you'd know if it was a bit high or low as it should sit right in the middle unless things are getting out of hand or the cooling fan/fan clutch, coolant/ radiator or pump are not working to spec.

[JMI]

Measurements in the Bently suggest that your 2135kOhm reading (if the sensor is good) was done at around 20 degrees C/68F. What was the ambient when you did it, and was the engine at ambient temperature?

Yes, 68F sounds about right.

Thanks