[trieschi]

Hello,
i need help with my bmw e90 320d from 2010 with the n47 engine.

At the first place i only had a problem with no crank no start after i parked my car and 30 minutes later it wont start anymore.

I thought its the battery and jump started it with another car. Since then the fuse f36 in the juction box burned which is responsiple for the cas 3 module in my car.

After that the wipers turned on when the key was in the ignition and some fault codes popped up in the dash.

I first tried to replace the fuse but when i press start + clutch the fuse burns instantly.

Next i tried to get the cas out and inspected the pc board but there is no damage at all.

After that i pinned out pin 22 of the cas connector because this cable connects to the starter motor. Then i tried to press start + clutch again and the fuse didnt burned. So i disconnected the negative terminal of the battery and tried to mesure pin 22 to terminal 31 (ground of the car). The multimeter says 0,06 ohm.

My questions now are:

1. Can the CAS be reposible for the problems in this case?
2. Is something shorted curcuit to ground?
3. What burns the fuse?
4. Could the starter motor be the problem?
5. Did i make the problem even worse because i jump started the car in the bonnet area?


Thank you for your help!
Sorry if my english is not perfect because im from germany.

[gbalthrop]

Originally Posted by trieschi

... e90 320d from 2010 with the n47 engine... fuse f36 in the juction box burned which is responsiple for the cas 3 module in my car. After that the wipers turned on when the key was in the ignition and some fault codes popped up in the dash. I first tried to replace the fuse but when i press start + clutch the fuse burns instantly...

I will attach to NEXT Post: ISTA ScreenPrints of the CAS activation of M6510a Starter Motor, via two connectors in the E-Box under the hood, X6011 & X60531.

F36, 40A, supplies the CAS Module "Load" circuit, which activates (KL50) the Starter Solenoid. Note the 2nd CAS fuse, F55, is the "Electronics" fuse, only 5A. My understanding is that fuse remains intact, & the F36 fuse blows ONLY when the Starter Solenoid is activated, via CAS Terminal 50 (KL50), pressing START while pressing Clutch.

So it appears there is a short-circuit, or contact with Chassis Ground, somewhere in the line between X13376/22 (Black wire) & the Starter Solenoid. The most likely points of such short-circuit are at either of the intermediate connectors in the E-Box, X6011/1, X60531/2, or in the line between X60531/2 & the Starter Solenoid.

You appear to understand HOW to test the wiring for Short-to-Ground. If the Resistance in the wire (Connectors at BOTH ends disconnected) is LESS than 0.30 Ohms, a 40A fuse will blow (12V battery voltage). Ohm's law: R = E/I. 12/40 = .3

If any questions about interpretation of the ISTA ScreenPrints, how to test, or any other ScreenPrints are needed of circuits, Component Locations, or Connector Views, please ask.
George

[gbalthrop]

Attached are ISTA ScreenPrints related to prior post. OP has MT, NOT AT, but wiring is SAME.
George

[trieschi]

First thank you George for that quick answer the screen prints are very useful.

Unfortunately i dont have ista but only a launch obd scanner.
The scanner gives me this three fault codes: 5DF4, 494A, 49FF.

But what would you do next to find the short circuit?
In my opinion i would reconnect pin 22 to the cas and disconnect the white wire in the e box and see if the fuse blows if not i would reconnect the white wire to the ebox an disconnect it on the starter and at least there the fuse must blow again.

When i do this i can figure out in which section the short circuit is or how would you go on if you dont have ista?

Thank you so much!

[gbalthrop]

Originally Posted by trieschi

... launch obd scanner... gives me these three fault codes: 5DF4, 494A, 49FF. [The correct definition of a fault code depends upon the "SGBD" or variant of the Module. INPA would tell you the SGBD of each Module. While I don't know that for your 320d, it appears the DSC has/had low voltage previously; 494A & 49FF suggest an issue with the Glow Plugs/Preheat system & voltage supply. I see NO relationship between the CAS F36, NO Crank issue & those 3 codes.]

But what would you do next to find the short circuit?

Unfortunately ISTA or INPA will NOT find the location of any short or wiring/connector fault. You have to use YOUR understanding of the KL50 circuit (CAS activation of the Starter Solenoid), & a Multimeter, as described (perhaps NOT well ;-) in Post #2, & ISTA ScreenPrints attached to Post #3. As stated in Post #2, it appears you have a short-to-Ground somewhere between CAS connector X13376/22 (Socket #22 of connector X13376, Black Wire), & the Starter Solenoid.

You do NOT have to waste fuses to test. Set your Multimeter to an intermediate Ohms/Resistance setting, say 20K Ohms max. Turn on meter. The value displayed on the meter screen is what you see for "Open Circuit" or infinite resistance. Some meters show "OL" or Open Loop for that. My cheap meters show "1" for open circuit.
Now, touch the two meter probes together. The meter should display something close to ".001" or nearly ZERO resistance. You can use that same meter setting to measure resistance/Ohms in any disconnected section of wire:

Try testing the Black wire between X13376 & X6011/1 as follows:
1) Disconnect connector X13376 from CAS Module & disconnect X6011 at the other end of the Black wire (X6011/1). You have to open the E-box to access X6011 or X60531. Please let me know if you need ISTA procedure for accessing/opening the E-box. Use a piece of wire (~ 3 meters) to connect to X13376/1 socket, with other end of that wire at E-Box.

2) Put one meter probe (either Red or Black/ does NOT matter) on Black wire from X6011/1. Put other Probe on jumper wire connected to X13376/22. Meter should display Zero, or nearly zero Ohms, meaning Closed Loop/circuit, e.g. ".001" Ohms.

3) You will probably find continuity in each section of wire between CAS & Starter Solenoid. You ALSO need to test for "Short-to-Ground" in each section, with Meter on same 20k Ohms setting, as follows:
a) Test ENTIRE section 1st, Black wire reconnected to X6011/1: Put one meter probe on metal socket of X13376/22 (Black wire) at CAS (X13376 DISconnected from CAS Module). Put other meter probe on good chassis ground (metal). Record the Ohms value displayed.
b) Repeat that test with X6011 Disconnected & record the Ohms value.
c) Follow the wire from the other side of X6011/1 to see where it goes on the way to the Starter Solenoid. I don't know where X60531 is & ISTA does NOT show the Location, just the Connector view. If you CANNOT identify that X60531 connector, please let us know.
d) disconnect X60531 & measure the resistance between X6011/1 chassis ground, recording that value.
e) Finally, with X60531 disconnected, measure Ohms resistance between X60531/2 & Chassis Ground, & record value.

Please report those Ohms values if the fault is NOT obvious. There have been reports by others of shorts at X6011 or X60531, so examine BOTH of those connectors closely, particularly if there is any evidence of moisture or corrosion.
George

[trieschi]

I've now measured all sections from CAS pin 22 to the starter solenoid. The wiring harness is fine and the short circuit isn't there. It's actually in the starter itself. When I measure from the starter solenoid to the starter housing or the vehicle ground, I get a resistance of 0.3 ohms.

Do you think replacing the starter will fix the problem?

Or should i do another test?

[gbalthrop]

Originally Posted by trieschi

... When I measure from the starter solenoid to the starter housing or the vehicle ground, I get a resistance of 0.3 ohms...

If there is only .3 Ohms resistance from X6510 (where White wire connects to Starter Solenoid) to Chassis Ground, YES, your Starter/Solenoid has an internal short. 0.3 Ohm resistance is low enough (sufficient short) to blow a 40 Amp Fuse (F36).

I would agree that your reported results indicate the fault is in the Starter, NOT CAS or wiring. Was there ANY "Click" from Starter Solenoid area when START button was pressed along with Clutch? Please let us know what you find.
George

[trieschi]

I heard a click but unfortunately i was at the driver sear and i think the click is the sound when the fuse blowed. So i cannot confirm if the starter clicks.

I've been wondering whether I should just apply 12V directly to the solenoid and see if the starter motor turns, but I'm hesitant because I don't know what will happen if the starter is actually short-circuited and whether I might damage the new battery or other components.

What's also interesting is that this braided cable has a purplish-blue discoloration; I don't know if that's normal or due to the short-circuit current which generates a lot of heat.