97 318is engine cut out around 2700 rpm and then again at 4000 rpm

[bmwdirtracer]

Well, okay then.....I can't explain those voltage results, but I'm sure very happy that you've got a car running correctly again!

All the best.

[polygaryd]

fan still turns on what looks to be low speed at 220 degree f with new fan switch. My temp readings are from the car computer through the obd2 data stream and my code reader. so it could be off??

[bmwdirtracer]

As you know, the fan switch is in the radiator. The coolant temp sensor which reports to the DME will be in the cylinder head. While certainly, there will be a difference in actual temperature between those two spots, it's not going to be 30 or more degrees.. Likely, the ECT sensor in the head is telling the DME the wrong temperatures. You could potentially have your engine running lean because of the bad temp info, so it might be worth your while to check actual temp (at the engine side of the top hose) with an infrared temp gun. {Due to the reflectivity of aluminum, it doesn't read very accurately, unless you give it a spray of flat black paint, or put a piece of masking tape on it, etc.}


ECT sensors are usually very inexpensive; you could just order a new one if you don't want to find an infrared gun and compare temps. (Still, it's always nice to have an actual reading, from a temp gun...)

The sensor which reports to the DME is at page 343 of the adobe document, view 2:
http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf

[polygaryd]

So the original fan switch was probably ok then you think and the ect sensor was the culprit the whole time(as far as the rad fan situation goes)?

Also the transmission fault light and the traction control light came back on after driving for a bit. Check engine light is still off and engine isn't cutting out. How can I read the codes from the transmission module codes? How to tell if the module is good or bad or if the transmission itself is good or bad?

[polygaryd]

Used dme I got off ebay that tested good and drove fine for 2 days is now dead same as the last one...

[bmwdirtracer]

Uh oh.....new problem here? Are you saying that your DME has just died? And you saw a Trans and traction light just before that?

Please clarify; last I knew the car was driving fine, but voltage on the throttle position sensor was still weird.

As an off-the-wall item: has anyone messed with the relays on the car, before this all began?

[polygaryd]

it seems dme has just died, car is cutting out like it was before and just before that happened the trans fault and traction control light same on. the voltage on pin 1 was 4.99v basically 5v for the feed wire. Signal wire pin 2 was still higher than signal wire on my 99 e36 m3 bmw at 5.78v. do you mean the voltages when plugged in to the tps were weird or just from the connector when not plugged into tps key on car off?

It was working fine for two days and now is back to the same exact issue. no-one touched the relays or anything before these issues started. car needed to be jumped and has a subwoofer sound system in it without a cap which will be fitted shortly. I figured the jump or the subs may have fried the dme the first time but this time the stereo stayed off and car wasnt jumped.

bad voltage to dme???

[328 Power 04]

You wouldn't happen to have any equipment to clear adaptations on the car, would you?


I was thinking that this is due to 2 scenarios:
1. Replacement DME learned the same adaptations from sensor inputs..
2. A short in wiring or sensors fried the DME in the same way the first one was fried. Which is what I was concerned about earlier, when I asked about shorts.

[polygaryd]

No I cant clear anything in dme but the shop that did the ews alignment cleared everything out, I watched him do it. How would the dme work for days and then short and only tps is effected? That seems weird to me that it would work and not fry right away with a short.

The wires look good everywhere too. I could pull the intake plenum and uncover the wires to tps I guess... or I could try to run brand new wires to the tps from the dme. not sure what to check next.

what other sensor inputs would make the dme change its voltage out put on pin 1 to anything but 5 volts? could the dme even do that as a learned behavior?

i find it hard to believe that the used dme was on its way out and failed so quickly but it is a possibility no?

[bmwdirtracer]

If two DME's fried in the same way, in the same car, one after another, there is ABSOLUTELY a wiring fault in the harness, (or perhaps the chip, but harness is more likely)

Does this car have a secondary air pump? {The SAP relay works entirely differently from all other relays, and will fry the harness and DME if placed in another location)

The outputting over 5 volts into the TPS signal tells me that there is a serious wiring issue.

[polygaryd]

yes it has one. I will check the relay. will it say on it sap or be a special color to denote what it is?

[bmwdirtracer]

from memory, the SAP relay is purple. It's best identified by the picture on the side. The SAP relay switches back and forth between 87 and 87a. Most normal 5 pin relays activate 87 and 87a at the same time. But on an SAP circuit, 87 is unfused hot, 87a is ground; a normal relay connects dead ground to unfused hot, melts many things if they're mixed.

[polygaryd]

The picture on the fuse panel wont tell me much except where the sap relay is supposed to be found, if I cant identify it by a special color or numbers on it then how will I know if the sap relay is in the right spot or not? Ya know what I mean? I still don't think that's it because none of them were touched to my knowledge and dont see why they would have or how they would have been by anyone inbetween the time the car worked great and now, all the wiring looks good, I checked the fuses also, not specifically the relays though but I was in that area and you said it melts many things which doesnt seem to be the case. I will thoroughly inspect it by taking it apart though.

What I also would like to know is if the dme is not fried but instead putting out a much lower voltage on the feed wire to tps from learning from other sensor inputs somehow, if it can be reset to put out 5v on pin 1 of tps feed wire again or not and if so how?

[bmwdirtracer]

I have to agree with Abel, that there's got to be a short in your wiring harness. It had seemed to me that the problem must be the DME, because 5.8 volts really isn't the sort of voltage you'll find in any wire....but now that you're seeing the same voltage, with a different DME, you're going to have to chase down a short in the harness....or replace the harness.

Between the DME and the TPS, there's the X6091 connector. This is a round 30-pin connector at "The rear of engine compartment on bulkhead". The signal for the TPS goes through pin number 6 of this connector. (If you want to see a drawing of the connector, go to page 379 of the adobe document (8500.0-05, view #6)

Have a really close inspection of that plug, both sides, to see if you've got corrosion, or naked wiring or anything else suspicious there. Otherwise, you're probably going to have to start slicing open the wiring harness sheath.

[328 Power 04]

(warning, open ended question, thinking aloud, may be wrong train of thought):

Would voltage reading on the TPS, with ignition on, and DME disconnected have any value?
I am thinking if there is some sort of stray voltage feeding into the 5.0V line from elsewhere.

Downside to this 'test' would be that disconnecting the DME would also stop many other voltage outputs.

[polygaryd]

With dme unplugged and key on there is 0.00v on both pin 1 to chassis ground and pin 2 to chassis ground.

I plugged back in the old dme with tps unplugged and got EXACTLY the same voltages on pin 1 (1.25v) and pin 2 (5.78v). How can two dme's fail and have exactly the same incorrect voltages, car off, key on, tps connector unplugged and chassis ground was used both times? That seems insane to me.

So I took apart the fuse box, checked all relays and the sap relay seems to be in the correct spot. i checked the pin out diagrams on the relays to make sure it matches your description. Absolutely nothing was out of place, nothing burnt, melted, frayed, not even corroded. So I opened the wire harness housing that sits under the wiper arm area and again every wire seems perfect.

So then I tested continuity from the dme connector unplugged from dme to pin 2 (signal) of tps with tps connector unplugged. Only pin 44 (if I'm reading the dme connector correctly) has continuity to tps pin 2 and everything else is a perfect open.

I also tested for continuity to from pin 1 (feed) of tps connector unplugged to dme plug unplugged also and found that a list of pins had continuity (not surprising that the dme feeds power (supposed to be 5v) to a variety of sensors) I am hoping you guys can tell me if there is anything askew with any of these pins having full continuity (0.00 ohms), some continuity(9 ohms was common) or none (infinite ohms).

pin 6 9 ohms
pin 8 full
pin 26 full
pin 27 full
pin 28 9 ohms
pin 34 9 ohms
pin 36 full
pin 42 full
pin 53 full
pin 55 9 ohms
pin 56 full
pin 80 full
pin 87 full
The rest are 900k ohms to infinite

I am going to check that x6091 as you suggested also and report back

I was thinking of unplugging all the other sensors that connect to the dme to rule out other possible voltage leaking/semi shorted sensors?? Then if the signal wire comes back down to 5v , plug each sensors back in one at a time till the voltage rises. What do you guys think?

[dworthy]

I have been just watching this thread, as the guys who have been helping are pointing you in the proper direction.

Pin 1 or the gry/wht is the supply voltage of 5V.
Pin 2 or the brn/vio is the signal based on how much open the throttle plate is. So the voltage should be at 5v closed and then drop as the plate is opened.
Pin 3 or the brn/blk is the shared ground. This ground goes back to the DME and is shared with IAT, Knock sensors, and ETC.

So based on that thought, check the other sensors to see if there is a feedback into the ground like you are suggesting.

Also the TPS, is it the OEM one, or a aftermarket replacement?

Another thought came to mind as it maybe something else completely shorting out the DME, and a full pin-out test could help point to that.

[bmwdirtracer]

You're doing a great job of checking and testing!


Okay, maybe some useful stuff; I just spent some time with your diagrams.

The pins you mentioned as having 9 ohms resistance to your feed wire ALL are on the exact same circuit: they go to GROUND, at the rear of the right hand shock tower, underneath the big round connector (likely the diag port). Inspect this ground point, and all wiring between it and the DME. (Picture of this ground point is on page 332 (7100.06-view 2)

Also, this same spot has the ground for the MAF. Therefore, with DME harness connected, and battery connected, you should test for voltage at your TPS signal wire WITH THE MAF UNPLUGGED.

(And, um, did you mention a stereo in here somewhere? Is it COMPLETELY disconnected, both power and ground?)

Also, with harness unplugged from the DME, and from the TPS, see if the signal wire has any continuity to ground.

Then, disconnect both terminals of the battery, and hold the cables together for a minute, then test if your signal wire has any continuity to B+ (the underhood B+ is fine). I caution you that the battery must be unhooked completely, and the cables held together for a minute to discharge any residual electricity.

Chris

[polygaryd]

Hi thank you for the info everyone. I just read your new posts for the day after I did a bunch more testing myself and came on here to post it to you. I have since unplugged ALL sensors ( i think)going to dme and any other connection i could find even. so this includes, maf, tps, iac, ect, the tps for the asc, the asc, throttle body motor, the knock sensors, the cam and crank sensor, the sap solenoid, the ac clutch, the hood open switch, the coil pack, the injectors, the oil pressure switch (i think), the x6091 connector and the 3 round connectors just like the x6091 that are hooked onto the side fuse box too.

My results are... voltage still high on pin 2 at 5.78v BUT voltage at a steady 4.99v on pin 1.. After I hook up the first (closest to the front of the car) x6091 connector looking things that are hooked to the side of the fuse box (before reconnecting that I got 0v on both pin 1 and pin 2).

So I start connecting other stuff (ac clutch, hood open switch, asc throttle body motor nothing else except the things in my next statement) to see if voltage drops on pin 1 or pin 2 and sure enough if I hook up the smallest third(closest to firewall) x6091 round connector looking thing the voltage drops on pin 1 to 1.25v instantly.
I unplug that same connector and its back to 5v on pin 1, pin 2 is still high throughout all of this plug the round connector back in and it drops, unplug and it sits at 4.99v steady...
MAF was not plugged in when any of these readings were happening. So my question is what runs through that small rear most round x6091 type connector, and does this mean dme is still good??

[polygaryd]

oh and this is still with the replacement tps but these readings are all from the plug of the tps with the tps not hooked to it so atm I feel that its irrelevant to the voltage findings whether or not its oem bmw or not. Mainly because when I received the replacement dme I hooked up the dme but left the tps unplugged and tested the voltages from pin1 to chassis ground and pin 2 chassis ground eliminating a possible ground issue and eliminating the possibility of a failure from the tps that could maybe cause the dme harm in the event the tps was bad. Voltages were 4.99v on pin1 and 5.78 on pin 2 and tps was never plugged. When tps was plugged in after I got the ews aligned and car would run it worked fine for a few days and then quit BUT voltage on pin 2 was high from the start so it couldnt be the tps causing the high voltage it must be something else.

[bmwdirtracer]

Um, hang on a minute.

According to what you just wrote, you disconnected all these items, INCLUDING the X6091....and you showed 5.78 volts on pin 2, and 4.99 volts on pin 1 of the TPS connector?

IS THIS CORRECT?

Because with the X6091 disconnected, none of the wires of the TPS are connected to ANYTHING!

And THAT means that you've narrowed down your problem a whole bunch, because the short is between the X6091 and the TPS.

The ETMs do not show a picture of the exact location of the X6091.
In the ETMS, I see the x6002 (diag, I think) on the passenger side, followed by a much smaller X6150.
On the driver's side is the X20 (connection between body electronics and engine harness), followed by the smaller X69.

Which side are you on?

Since the pictures only show two connectors each side, and you're talking about a third, I'd guess that might be the X6091. Does it have 30 pins?

[polygaryd]

IMG_20170226_155803.jpg

drivers side the one to the left is the one that needs to be plugged in to get any power to dme, the one in the middle doesnt effect anything either way and the one thats unplugged is the one that drops the voltage down to 1.25v when plugged in.

[polygaryd]

IMG_20170226_171625.jpg

voltage on pin 1 with round connector near the firewall disconnected

IMG_20170226_171651.jpg
pin 2 voltage with round connector near the firewall disconnected

- - - Updated - - -

IMG_20170226_173541.jpg

ok so I disconnected the battery and held the ends together and then retested with the small connector to the right connected as well as disconnected (5v on pin 1 feed) and its now showing 1.8v instead of 1.25 on pin 1 feed when round connector near fire wall is connected.

I also disconnected the stereo and the amp completely before this pic was taken so it can be the car audio system. It was an after market pioneer deck with a rockford fosagte amp for subs only. I'm not sure if there was a factory amp like in my m3 or not if there is its still connected, if there isn't well then its not connected

pin 2 never changes voltage no matter what i do

[polygaryd]

did what you said and disconnected the battery again, held the ends together for over a minute, tested signal to ground and signal to b+ under the hood with tps and dme connectors unplugged ofcourse and no shorts, infinite ohms is showing for both.

[polygaryd]

im trying to find the pin out of that small round connector that I have to leave unplugged for the voltage to stay at 5v and I cant find it in the massive pdf you gave me a link to. Maybe im blind but i cant find it so any help would be appreciated.

other thoughts on the matter:

if the voltage will come out on pin 1 at 5v and then drop when that small round connector is plugged in then the dme shouldn't be bad, which mean there is some resistor or motor (load of some type) effecting the dme by a short to something such as another sensor or a module but not a short from power to ground otherwise it would blow fuses or burn up the dme to where it can no longer put out 5v on pin 1 to tps ever.

Since it took 2 days after the shop guy cleared the dme faults for this issue to show up again AND now it will take 2 minutes roughly after disconnecting the battery for a few minutes and reconnecting it while having that small round connector plugged in, for the voltage to drop on pin 1 of tps. There is something that has a delayed start to invoke the load on the power feed pin 1 to tps.