Crank sensor

[eligunn]

I've got a 95 525 that won't start, and I was trying to determine whether it is the crank reference sensor or not.
In my Bentley manual it says the resistance for the M20/M30 is 540
And for the M50/M60 is 1280

Well my car has an M50 engine and the test I did came up with 492 ohms which would've been within spec for the M20/M30 but not the M50, so I ordered another crank sensor and when I got it it tested at 516 ohms.

So my question is, should I ignore what the Bentley manual says and assume the crank sensor is good or should I try to get another sensor.

Can anyone verify for me whether or not the manual is wrong.

Thanks alot

[eligunn]

Somebody has to know this.

[Jeff N.]

Can't advise on the CPS readings - 492 is pretty close to 540 but, obviously, 516 is closer.

What diagnotics have you done? Did you run the stomp test and get a CPS code? Have you checked the fuel system to make sure it's pressurizing? The fuel pump relay is a common failure on these cars.

My advice, stomp test the car and get the codes. Verify you have fuel. Then worry about a 40 ohm variance on a CPS.

Jeff

[ryan roopnarine]

bentley is wrong, winfred says so and every m50 i've measured says so. the cps should be around the m20/30 value in ohms. i think that winfred said that the 1280 value is for the cam position sensor or such.


I've got a 95 525 that won't start, and I was trying to determine whether it is the crank reference sensor or not.
In my Bentley manual it says the resistance for the M20/M30 is 540
And for the M50/M60 is 1280

Well my car has an M50 engine and the test I did came up with 492 ohms which would've been within spec for the M20/M30 but not the M50, so I ordered another crank sensor and when I got it it tested at 516 ohms.

So my question is, should I ignore what the Bentley manual says and assume the crank sensor is good or should I try to get another sensor.

Can anyone verify for me whether or not the manual is wrong.

Thanks alot

[eligunn]

Thank you for that information.

I did a fuel pressure test and the fuel pump put it ir right up to 50 pounds instantly.
The first thing I did when the car wouldn't start was swap the fuel pump relay with the oxygen sensor relay, and later again with another extra relay with no results.

So I kinda ruled out the fuel pump relay, although I guess that could still be it.

I pulled a plug and it had gas on it which makes me think the injectors are firing.

I checked the dme relay and it seems to be working.

The Bentley manual is nebulous about checking for spark on distributorless ignitions.
What's the proper procedure for this?


Thanks

[eligunn]

Oh yes, I did a stomp test with no results, even when I had the cps unplugged. Which makes me think the check engine light is not going to tell me whether it's the cps or not

[SRR2]

Anything made with hundreds of turns of fine wire is going to have a significant variance in resistance from run to run and even from unit to unit. It's the nature of wire. Assume that if it's within 25% of nominal, it's somewhere in the ballpark. However, the resistance doesn't tell you too much about its functionality, only that the wire is connected at both ends. You can still have shorted turn(s) that would severly degrade output but never show up in a resistance test.

You can test functionality if you have a DMM. Hold the tip of the sensor near the teeth of a rotating gear or sprocket (make sure they're magnetic, not stainless or aluminum alloy especially if you're using a bicycle sprocket). You should measure a nontrivial AC voltage from the sensor. Guessing, I'd say that anything over a couple of hundred mVAC (and it depends on how close you hold it to the gear) would be OK.

[eligunn]

It's still in there.
could I just crank the motor over and measure voltage between terminals 1and 2

[Javier]

1 or 2 to the third shielding wire (if the sensor wire is grounded it will not work, no mater the pick up coil is ok).

Javier