E36 P0340 Code After Cam Sensor Replaced

[bmwdirtracer]

There's absolutely still a problem. The feed voltage should be 5 volts. The signal voltage, I'm not sure how much it should read, or when. But 2.5 volts, shared between the 2 lines, is way wrong.

You get NO voltage on EITHER wire, when the sensor is plugged in? That's even more strange.

Try this for me: Plug in the cam sensor, backprobe the feed wire (and later, backprobe the signal wire), and check the voltage....and then rotate the engine, and see if voltage changes on either circuit.

MAYBE the cam sensor is at the trigger point, so let's rule out that possibility. But given your 2.5 volt readings, I have to think that there's still a short. I cannot explain lack of continuity with your ohm tests, unless the short only manifests when the circuit is powered. (This is why resistance tests are self-limiting).

Have you priced an engine wiring harness, from a salvage yard?

[HeliHover]

Here's pics I took.

Havent check prices on harnesses yet. I'll go do another check.

[328 Power 04]

What can I test on my confirmed bad DME, to have a DME test procedure? I'll have to dig out a multimeter, but I can power up the DME on desk.





Although an unlikely chance... a used DME can still have the same problem, because that cam sensor connector with stripped insulation is becoming more and more common.
Mr. Markert told me that for these cars, the most common need to replace the camshaft position sensor was for that wire insulation problem.

[HeliHover]

What can I test on my confirmed bad DME, to have a DME test procedure? I'll have to dig out a multimeter, but I can power up the DME on desk.





Although an unlikely chance... a used DME can still have the same problem, because that cam sensor connector with stripped insulation is becoming more and more common.
Mr. Markert told me that for these cars, the most common need to replace the camshaft position sensor was for that wire insulation problem.

That thought crossed my mind too. I have the old one installed still, but who knows now..... Maybe I should put the other one back in....

Dirtracer, I just went out and cranked the engine after the test and got the same results. The car was even moved in between the two different test.

[328 Power 04]

Well, although I will be a little slow (a few days) to produce results, I have 2 cars with the MS41 DME in perfect working condition, 1 spare S52 engine, and 1 bad spare MS41 DME...

Lots of cars to pull info from. Honestly, the first thing I will do now is disconnect the camshaft position sensors on all and verify for insulation, before even powering on the cars.
The spare S52 engine's sensor looked just like your original camshaft position sensor, and the engine has a confirmed 120,000 miles.

I will probably check the M52tu's sensors too, but those have already been changed.

[bmwdirtracer]

Dave Markert knows his stuff, for sure.

As for what you can test, on a bench, my friend, I really have no idea. As a guess, I think our friend Mike has a wiring harness issue here. I have no doubt that it fried the original DME, but I'm worried that if the new DME is hooked up to a shorted harness, it might just fry the new DME also. Maybe you could ask Dave about that possibility? Though I'm familiar with his reputation, particularly regarding S54 wiring harness swaps, and I've spoken with him regarding these, I doubt if he knows me by name.

And Mike, I generally do not jump to expensive conclusions on matters like this. I rarely call computers bad....until they prove it. But 2.5 volts is not a good number, especially when it's showing on both the power feed AND the signal wire. And if both voltages disappear entirely when the sensor's hooked up? That's just all too weird. That's why I ask that you rotate the engine, and then remeasure the voltage.....maybe this is an anomaly of the cam sensor trigger, that the voltage disappears. (I doubt it, but let's check.)

What side of the harness does that burned insulation live? Is this on the sensor side of the plug, or the harness side of the plug? I assumed the DME side.....(Please keep in mind that I don't deal with many E36's these days. I have to rely on diagrams.)

As common as the problem may be, there's just too much coincidence in thinking that two DME's died in the same way.

Let's remember that's it's Saturday night, and I've had one too many beers, too. Maybe Sunday morning will provide an epiphany.... but damn, the time changes tonight....maybe not.

[HeliHover]

Dave Markert knows his stuff, for sure.

As for what you can test, on a bench, my friend, I really have no idea. As a guess, I think our friend Mike has a wiring harness issue here. I have no doubt that it fried the original DME, but I'm worried that if the new DME is hooked up to a shorted harness, it might just fry the new DME also. Maybe you could ask Dave about that possibility? Though I'm familiar with his reputation, particularly regarding S54 wiring harness swaps, and I've spoken with him regarding these, I doubt if he knows me by name.

And Mike, I generally do not jump to expensive conclusions on matters like this. I rarely call computers bad....until they prove it. But 2.5 volts is not a good number, especially when it's showing on both the power feed AND the signal wire. And if both voltages disappear entirely when the sensor's hooked up? That's just all too weird. That's why I ask that you rotate the engine, and then remeasure the voltage.....maybe this is an anomaly of the cam sensor trigger, that the voltage disappears. (I doubt it, but let's check.)

What side of the harness does that burned insulation live? Is this on the sensor side of the plug, or the harness side of the plug? I assumed the DME side.....(Please keep in mind that I don't deal with many E36's these days. I have to rely on diagrams.)

As common as the problem may be, there's just too much coincidence in thinking that two DME's died in the same way.

Let's remember that's it's Saturday night, and I've had one too many beers, too. Maybe Sunday morning will provide an epiphany.... but damn, the time changes tonight....maybe not.

No, I'm not getting voltage on the signal wire, only the two power wires. When I test the signal wire I get no voltage, but can hear some type of click, like a relay.

The wires I posted shown with the deteriorated insulation, was on the old cam sensor, not the DME side.

[HeliHover]

If it is indeed a shorted harness, can I run a 3 wire lead from the sensor to the DME outside of the harness? This should work right? Or at least eliminate that possibility.

[bmwdirtracer]

One power wire. One signal wire. One ground.

[HeliHover]

I found a harness for 50 bucks....

I'm going to run 3 wires from the DME harness plug to the sensor and see what happens. I'm also going to check continuity on each of the 3 wires to ground. I should only see one of the wires test positive, but I have a feeling I might see some resistance on one of the other ones. I'll report back tomorrow.

Thanks for all the help and time spent on this. You guys are awesome!

[HeliHover]

I cut the harness and checked voltage straight off the DME and I still get 2.5 volts:/

[bmwdirtracer]

I can't begin to explain that.

Abel, any chance you could go check your cam sensor plug, and see what voltage it's getting?

I've heard of 12 volt sensors and 5 volt sensors, but I've never heard of a 2.5 volt sensor -- nor one that gets power from two different wires!

[HeliHover]

I just tested my daughters 5er and got the same 2.5 volts.

[bmwdirtracer]

https://www.youtube.com/watch?v=eZIr-rp1FSc

That's a Bentley Instructional on testing a cam sensor, although it's on an M54 engine. As you'll see, there's one power (although this one is 12 volts), one signal, one ground.
I'm really not understanding what the difference is, to the sensor in your engine, but obviously, the earlier engine's cam sensor isn't working the same way at all.

In your car's computer pin-out, both cam sensor wires which are NOT the ground show as being INPUTS to the DME.

I'm going to try to find some explanation as to why an M52's cam sensor works so very differently from that of later motors......

[HeliHover]

Is there anything inside of the engine that could have failed to cause this?

[bmwdirtracer]

No, there's no indication at all that this could be anything other than electrical / electronic.

[HeliHover]

Man I'm going nuts trying to figure this out. I'm reading articles unrelated to BMW, but the general thought process is identical.

I have this narrowed down to this.
- Both DME's I have might be bad. I'm tempted to pull the one out of my daughters car.
- The timing is off internally. Isn't the cam sprocket slotted? Is it possible for this engine chain to jump a tooth under some crazy condition?

I have tested the harness so many different ways today and I feel 100% there is no problems.

Even though all most every generic mechanic page say a bad crank sensor will throw a 0340 code, none will confirm a no start if this is the problem. I will say having the car longer and paying more attention and watching a few videos, this car does exhibit a hard start, which is a symptom of a bad cam sensor. I'm positive the car is lacking power too. According to almost everyone, the car will not start if the crank sensor is bad. The car always starts and never has not, so this shouldn't have anything to do with the crank sensor. Thats my thinking anyway.

If I have two bad DME's, why did my daughters car test the same? This would only leave something internal on the engine.

[bmwdirtracer]

I don't know the year of your daughter's car, but I'd guess it has EWS 3.3, and you're not going to just slap that thing in your car, and have it work. I think you'd be a lot better off swapping the crank sensor!

Hell, UNPLUG your crank sensor, and see if the car will start.....

[HeliHover]

I don't know the year of your daughter's car, but I'd guess it has EWS 3.3, and you're not going to just slap that thing in your car, and have it work. I think you'd be a lot better off swapping the crank sensor!

Hell, UNPLUG your crank sensor, and see if the car will start.....

OK.

I'm done for the day....

I thought my daughters car had the same DME. It has the same m52 2.8. It's a 98'.

[MIKYZZ4]

Just for verification, are the present results and readings occurring with Genuine BMW crank & cam sensors installed, not aftermarket?

[HeliHover]

It's a Meyle brand which is the second one I've tried. The first one was different brand from the same import store.

[328 Power 04]

Your daughter's car, is it single vanos? If yes, you can try it in your car.. Align ews and you're good to go.
The EWS module takes the DME ISN, so nothing will change about the daughter's car.

[HeliHover]

Yes single VANOS.

Ill probaly give that that a try sometime this week. It's hard to cross paths with her. She works 2 jobs and is still in school.

On on a good note, the brand new soft top is rad! It looks so good and I finally have it dialed in. Opens and closes perfect and, zero leaks in this terrible monsoon we're in up here.

On a a bad note my wife and kids were at diary queen getting ice cream and got backed into while sitting in the drive through:/. We'll find out the damage today.

[328 Power 04]

What would happen to your voltage readings if you place that sensor against something ferrous, where the electric field changes, simulating the camshaft read plate?

[bmwdirtracer]

I wondered that myself, Abel. But I was thinking of watching the two voltages as the engine was turned by hand; I'd bet one must go to 5v, and the other drops to 0v, at some point.