Crank No Start : Problem: No FPR #85 Ground with Ign On SOLVED!!

[Grasshopper2Ant]

1992 325i Coupe M50 engine.

Started car drove it 30ft then parked for one day, now no start. Never happened before.

Have did tests, jumpered relays etc. No fuel/ no spark.

Want to start from scratch. Can a bad Crank Sensor cause a no fuel/no spark issue??

Can I check the crank sensor without taking it out of car by pulling the pin connector and putting multimeter to it? Or do I have to bench test it out of car?

Any other test to perform to troubleshoot welcome.

[BimmerJM325is]

Yes, you can disconnect the connector under the intake manifold and test for resistance. It should read around 500 ohms

I made this list when my m50 died on me!

Battery charged?

Fuses, Fuel pump Fuse 31

Water in ECU?

Relays: Fuel pump relay.. Power? Signal from ECU? Switch FP relay with horn and test for priming.

Vacuum leak: Check intake elbow and hoses to TB.

Spark: Pull coils and plugs for visual inspection.

[Grasshopper2Ant]

Thanks for reply.

CPS tested fine on the car at 508 ohms.

I am confused at this point as I have no fuel or spark.

Going to double check jumpering FPR for fuel.

Any suggestions out there welcomed.

[Grasshopper2Ant]

1992 325i coupe M50 engine.

Started a new thread for specific problem.

Tested CPS at 508 ohms which I assume is OK.

There is power going to the DME relay at #30 and #86 with IGN OFF.

#85 is a switched ground. I can jumper it and it makes sounds like the fuel is working.

I have switched DME and FPR relays, still no power to #85s on both.

How can I find my problem?

Any input appreciated.

[Eric93se]

Checked all fuses? What is the battery voltage?

[Grasshopper2Ant]

Checked all fuses? What is the battery voltage?

Fuel pump relay fuse #18 is not working as a result of no power to DME #85 with IGN ON.

Battery is 11.94V. I put my booster pack at 12.64V to it and it cranks fine.

I jumpered fuel pump relay and it gets fuel out of fuel line.

Why am I not getting power to DME #85 with IGN ON??

[Eric93se]

The 1992 325i 2.5l, in the benltey manual pin 85 on the DME is a pressure switch. I suggest you download the Bentley manual so that you can properly diagnose.

[Grasshopper2Ant]

[QUOTE=Eric93se;29956912]The 1992 325i 2.5l, in the benltey manual pin 85 on the DME is a pressure switch. I suggest you download the Bentley manual so that you can properly diagnose.

Thanks for link. I will try to look at DME schematic for clues. Is the #85 on the DME the same as the #85 on the DME relay?

The DME relay #85 is a switched ground. It becomes hot (12V) when IGN ON but that is not happening.

[spyderg0d]

I think there's a communication error on that part. You mean pin 85 of the dme relay not pin 85 on the dme.
I would agree with Eric on this one that you should download the wording diagram specific to your car. Troubleshoot the grounds and power with the pin related.
Otherwise, i would suspect the ignition switch or the ews. Possible drive away protection was activated.

[Grasshopper2Ant]

1992 325i Coupe M50 engine.

Camshaft sensor from above vehicle. There are 2 pins. How do you test and what is a good reading.

i have read you have to place a piece of metal on it to get a reading so I am confused.

Any help appreciated as I am trying to fix a crank no start issue.

[drstuess]

I believe it is a hall effect sensor, so it can be unreliable and hard to test. Also, I could be wrong, but cam sensors generally don't seem to cause crank/ no starts. It is usually the crankshaft sensor.

Sent from my SM-G930V using Tapatalk

[JDStrickland]

CRANKSHAFT POSITION SENSOR SPECIFICATIONS
1280 ± 10 ohms, there is also an air gap specification that's critical, it should be 0.04 ± 0.01 inches.

My manual has no specification for the cam sensor. The sensor is a Hall affect thingamabob, so the resistance while installed will reasonably change depending upon the distance of the teeth on the tone ring.

If there is no signal detected from the Crank Position Sensor, the engine will not start.

I missed the part about why you are working on your car, but if it's a no start issue, then the crank sensor is higher on the list of usual suspects.

[JDStrickland]

Have you ever seen what the ABS (wheel speed sensor) looks at? The Cam and Crank Sensors look at exactly the same kind of thing.

A tone ring looks sorta like the sprocket on your bicycle chain, but there's a tooth missing that creates a long pulse every 360 degrees. The shape of the teeth is square, so the pulse that is established can be counted. If there are 18 teeth, then there is a pulse generated every 20 degrees, the ECM counts the pulses to know the position of the respective shaft that is it looking at. For the brakes, the wheel speed sensors are looking at the duration of the pulses, when there is a wheel that is making a longer pulse than the others in the circuit, it determines that one of the wheels has locked up, and the ABS kicks into action. Different use of the pulse, but the same generation of the square waves.

[shogun]

Based on realoem the crankshaft sensor is Pulse generator 12141726065 https://www.ecstuning.com/b-genuine-...r/12141726065/
and that has 540 ohm ,copied from a German website, same for various brands
Sensorart Induktivsensor
Anzahl der Prüfkontakte (pins) 3
Widerstand 540 Ohm
Kabellänge 725 mm

examples
https://www.daparto.de/Teilenummernsuche/Facet/90130
https://www.daparto.de/Teilenummerns...yle/3148998003
https://www.daparto.de/Teilenummerns...at-Doria/87110

TRIGGER CONTACT 12141726548 http://www.realoem.com/bmw/enUS/show...diagId=11_1281
here the web says https://www.daparto.de/Teilenummernsuche/LORO/12005016
LORO Art.-Nr.: 120-05-016
Sensorart Induktivsensor
Anzahl der Zapfen 3
Widerstand 1400 Ohm
Kabellänge 390 mm

not the first time that the Bentley is wrong, same was wrong for the M60 crankshaft position sensor in the original print, original was 1280 ohm, now they have online the correction to 540 ohm
Corrected page: Note: Changes are shown in Red https://wiki.bentleypublishers.com/d...specifications

and here a youtube, E36 CPS 540 ohm https://www.youtube.com/watch?v=CMJFrHqCo7U quote: Published on Aug 21, 2010, Checking resistance on the sensor to see if it is faulty. The Bentley manual says it should read 1280ohms but in reality the sensor should be reading around 560 ohms +/- 10%

confirmed here , 540 Ohm https://www.bimmerforums.com/forum/s...sor-resistance
Cam-Position-sensor-ohms https://www.bimmerforums.com/forum/s...on-sensor-ohms

As for
E36 - 323i and 328i with M52 engine produced 6/95 - 12/98
E36 - M3 with S52 engine produced 1/96 - 12/98
E39 - 528i with M52 engine produced 3/96 - 8/98
Z3 - with M52 engine produced 7/96 - 9/98
Z3 - with S52 engine produced 1/98 - 1/99
the story is different http://bavarian-board.com/uploads/kb...ion_Sensor.pdf
new version 12 14 1 709 616 Crankshaft position sensor, that is a hall sensor, 12V
like for example
HELLA: 6PU 009 110-421
VDO: S107230001
VEMO: V20-72-0403

Technical information from Hella: Crankshaft Sensor
General
Crankshaft sensors record the engine speed and crankshaft position. The fitting position is near the flywheel ring gear. More they are found on the engine block with the sensor ring bolted onto the crankshaft There are two different types of crankshaft sensors, a hall sensor and an inductive pick up.
Function
Their function is to send voltage signals produced by changing magnetic fields developed by the rotating ring gear to the ECU, for calculating the crankshaft speed and position. These are important signals for the fuel injection and ignition timing.

Effects of failure
A faulty crankshaft sensor can cause the following:
· Engine will not start
· The engine is misfiring
· Engine stalls
· Storing a fault/trouble code
Causes of failure:
· Internal short circuit
· Wire short circuit/open circuit
· Mechanical damage of the ring gear
· Soiling through metal abrasion
· Short circuit to vehicle ground

Diagnostics
For fault recognition consider the following system tests:
· Read out fault/trouble codes
· Check electrical leads and plugs for correct fitting and contact
· Check for soiling and damage
The checking of the crankshaft sensor can be difficult when the sensor type is unknown. Before checking it must be differentiate between a hall sensor or an inductive pick up. It is impossible to differentiate between them by sight every time. When they have three pins in the plug it is not sure which type it is, for that you need specific manufacturer’s data and details from the parts catalogue. If the type is not clearly identified don’t use an ohmmeter because it can destroy the sensor.
When the sensor has a two pin plug it is usually an inductive pick up. With the inductive pick up you can check the internal resistor, a short circuit to earth and the signal. For this remove the sensor plug and check the internal resistance, if it is between 200 and 1000 ohm (according the given value) the sensor is okay, if it is 0 ohm there is a short circuit and by Mohm there is a open circuit. For checking a short circuit to earth measure each pin of the sensor to vehicle ground, measured value > 30 Mohm. Measurement with an oscilloscope must have a strong enough sinus signal. AC voltage can be checked by measuring across the pins and spinning the wheel. With hall sensor you can only check the signal voltage (rectangular signal) and the operating voltage.

https://www.techtips.ie/Hella-Irelan...aft-sensor.pdf

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[Driiven]

you cannot test any sensor of this sort with a multimeter period. Use a scope and do cam/crank function and correlation on any vehicle . Sure if it is completely open or short circuit yes! but if it is dropping out you will never know. In 2 minutes with a dual/quad scope you will ascertain timing/wiring/ tonering-flywheel damage and sensor function without pulling so much as a the cover off.

[somebody5788]

you cannot test any sensor of this sort with a multimeter period. Use a scope and do cam/crank function and correlation on any vehicle . Sure if it is completely open or short circuit yes! but if it is dropping out you will never know. In 2 minutes with a dual/quad scope you will ascertain timing/wiring/ tonering-flywheel damage and sensor function without pulling so much as a the cover off.

What this guy said. /thread

[Eric93se]

Too much info about the crankshaft sensor in this thread when asked about camshaft sensor.

My camshaft sensor started throwing errors (inpa) and occasional trouble starting. I got a new sensor for just $20 from RMeuropean (ERA brand, italian manufacturer). Oddly the website listed it as ERB brand but the box label says ERA (funny logo design). Have not installed it yet.

I was under the impression that the early Cam sensors were inductive and the newer design is hall effect. I plan to measure gate potentials and compare the two since diagrams I saw a while back showed a transistor is used inside this sensor (hall effect version).

- - - Updated - - -

People were saying not to do basic resistance checks on the hall effect sensor due to the possibility of damaging it. The earlier sensors is fine to do the resistance check.

[somebody5788]

The OBD1 cam sensor is hall effect and the crank was VR. The OBD2 cam sensor is an AC signal to an extent and is very very weird, the crank sensor is hall effect. But no matter what sensor type or location, the correct test is a scope.

[Grasshopper2Ant]

Fuel Pump Relay #85 is not getting 12V, only getting (2.12V) on Pin #1 on DME connector with IGN ON.

Page 556/557 shows the engine management only.

I cannot find where the connector gets its power for Pin #1. Trying to trace Pin#1 back. Can someone post the electrical schematic page on Bentley for this.

What can cause this voltage drop?

Any tips on how to troubleshoot appreciated.

[shogun]

check the fusible link in the trunk, pic here https://www.bimmerforums.com/forum/s...0#post29660530

[Grasshopper2Ant]

Thanks, I checked my 4 connections at the + distribution box where you jumper your positive terminal under the hood and they all get 12V.
Going to have a look at the fuse link as I know where it is now.

[Eric93se]

The dme only gives power to the fuel pump relay for a second, then after the car starts it gets power full time.

[Grasshopper2Ant]

The dme only gives power to the fuel pump relay for a second, then after the car starts it gets power full time.

I get the power from the DME if I physically ground FPR #85 to car chassis.

With the DME disconnected, I only get 2.12 V at Pin#1 connector on the harness. I am looking to trace back why. IGN ON suppose to give it 12V.

Looking for the Bentley page number that can show this.

[shogun]

wiring diagrams are here, https://www.bmwtechinfo.com/etm/data/toc_cd2.pdf

[Eric93se]

So I just replaced my cam sensor. I am OBDII, so it's not the same sensor as the OP. The new sensor, Pins 1 to 2 and 1 to 3 measure 9.5ohms. The old/bad sensor those pins only measured 0.5ohm, so basically dead short. So the bentley manual has a high number for this sensor and that is because it's not the same as this one (OBDII vs OBDI).

- - - Updated - - -

Car runs great again, starts very fast.