OBC - some functions work, others do not

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MinneapM635
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OBC - some functions work, others do not

Post by MinneapM635 »

I was wondering if anyone had thoughts on why my OBC does not show any value for MPG, average MPH, for example, but temp, clock, timer all work. Well, the outside temp reading seems high, but at least there is a reading.

No amount of holding down the reset button does anything. The MPG and avg MPH just show -- --. I know there is a relay involved with the OBC, is it possible this is bad? Other thoughts?

Thanks!
'85 "Arctic Blue" M635
'01 Silver 540iT Alpina tribute
V

Post by V »

AFAIK the input for those functions come from the cluster. Make sure the plug to the OBC from the cluster is connected?
MinneapM635
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Post by MinneapM635 »

What do you mean by cluster? Where would I find it?

Thanks
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Hefeweizen
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Post by Hefeweizen »

I don't think it is a "cluster issue" since the temperature is also coming from the cluster. There is a green plug going into the back of the OBC which delivers all the data.

What OBC do you have? Based on your signature block you have a Euro.
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MinneapM635
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Post by MinneapM635 »

I have the more recent style OBC (more buttons, 1, 10, 100, etc).
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Post by Hefeweizen »

Maybe you need to reset? I found this website with the OBC functions:http://www.bieveien.com/home/bmw/obc/obc_tips.htm

If you suspect a relay you can always look this up at the ETM at:
http://www.armchair.mb.ca/~dave/BMW/e24/
Rainer
03 330Xi (DD)
85 635CSi (RIP 3 May 19)
80 633CSi (Red Euro, Project)

"If you think a good European mechanic is expensive, try a bad one!"
MinneapM635
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Post by MinneapM635 »

I have definitely setup the OBC, but not sure about resetting it. When I bought the car, the display was flashing -- --. I used the reset pin to set the units and set the time and date. Everything in that realm has worked since.

It's like the features that the OBC relies on the ECU for are not working. At least, that is how I see it in my head.
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Post by Hefeweizen »

If it wasn't such a PITA to take them out I would suggest to put a known good one from a fellow 6er owner in Minneapolis/ St Paul in. May just be that these functions don't work in your OBC?
Rainer
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85 635CSi (RIP 3 May 19)
80 633CSi (Red Euro, Project)

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Post by Brucey »

there are signals into the OBC for speed and injector timing.

That the average speed and mpg don't work may indicate that you are missing the 'speed' signal.

Is your speedo working?

-just a thought....

BTW somewher on the internet there is a good explanation of how the early OBC system works...


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MinneapM635
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Post by MinneapM635 »

Yep, speedometer works flawlessly. I imagine though that the speed sensor signal is somehow routed from the gauge cluster to the OBC... maybe that wiring is bad or missing?
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Post by Brucey »

yes, I think so too, that may be worth investigating...

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Anri
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Re: OBC - some functions work, others do not

Post by Anri »

Hi,
I was just about to post the same question !!!!!!

I found the problem! The mother board was bad, I did change it with spare I have and now works perfect !

Before you do anything make sure the BLUE and WHITE Cruise Control plugs are on the CORECT position if they are not it will show that fault!

Make sure you do all the swap slow without braking anything becasue this is 20 years old plastic and they brake easy.

I guarentee you will fix the problem.

I checked anything possible including the OBC computer.. and was not working untill today.

Good luck let us know


Anri
MinneapM635 wrote:I was wondering if anyone had thoughts on why my OBC does not show any value for MPG, average MPH, for example, but temp, clock, timer all work. Well, the outside temp reading seems high, but at least there is a reading.

No amount of holding down the reset button does anything. The MPG and avg MPH just show -- --. I know there is a relay involved with the OBC, is it possible this is bad? Other thoughts?

Thanks!
E24 M6 Schwartz/Tan 3.8
E24 M6 Zinnoberrot/Tan 3.5
E24 M6 Royal blau/Dove. 3.5
E24 M6 Schwartz Track-Toy 3.6
E31 '97 840Ci Schwartz/black.
E30 M3 Diamond Schwartz
MinneapM635
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Post by MinneapM635 »

Anriart, thanks for the heads up on how you fixed the issue. One question, is the motherboard located in the OBC under the steering column, or is it part of the OBC display panel near the radio? I will definitely check mine out to see if there are any obvious issues. I just need to know where to look.
'85 "Arctic Blue" M635
'01 Silver 540iT Alpina tribute
Chris Wright

Post by Chris Wright »

MinneapM635 wrote:Anriart, thanks for the heads up on how you fixed the issue. One question, is the motherboard located in the OBC under the steering column, or is it part of the OBC display panel near the radio? I will definitely check mine out to see if there are any obvious issues. I just need to know where to look.
You say you have the later style OBC?

The "Computer" is in the display head and the relay box next to the steering column has nothing but two relays in it, one that cuts off the power to the main relay if the anti-theft is set, and another that sounds the OBC "Theft" horn. There are no inputs from the OBC relay box to the OBC. (BTW, the outside air temp sensor goes direct to the OBC and does not go through the instrument cluster).

I'm guessing that Arni is talking about the instrument cluster mother board, they can get corroded if the batteries leak. Check all the connections to it first, as he suggests. Here is how to remove the cluster:

http://www.z3bimmer.com/OffTopic/E24Bimmer//OdoGear/
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Anri
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Post by Anri »

Hi MinneapM635,

What you should check right away is the mothe board located inside the cluster behind the instrument gadges, green color. You have to be carefull when remove/swap the parts to onother good working condition motherboard.

The best way to test without weisting time doing road test, having the cluster and other stuff away from the dash...

Jack the car in the air from the differential and use jack stands to keep the car in the air. Lock the front wheel using something around the tires. Start the engine push the clutch with a left hand, right hand shift the shifter right on 5th gear and slow release the clutch. and then you can play with the gas pedal not with much... and then you will see if the OBC works or not. This may sound crazy but after you try you will see how easy is...

Well I feel like you are not well handy with the E24 chasis are you ? Let us know we if you need more info.

ANRI
E24 M6 Schwartz/Tan 3.8
E24 M6 Zinnoberrot/Tan 3.5
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Anri
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Post by Anri »

To Chris,

Hey Chris I finally found why the cuise was not working on my 87 M6 ! It was the mother board ! Check this out, I went with the cluster to speedometer shop and he tested the cruise impulses on his computer screen/mashine. It did show to work perfect !

Also, on my 87 M6 the cruise control plug in the back saying Weib (white) and Blau (Blue) for some reason the Blue plug is Green Grun and I was keeping folowing the factory instruction matching color from the plugs to back of the cluster. Know, I have 2 nd M6 88 model and removed the cluster from that one and the first impresion was the the Blue plug into Blau place. I try the cluster from the 88 to the issue car 87 using the green plug to Blau place and it worked right away. So basically some one from the assembly line when car was new used green instead of blue conectror. Car has 61k original miles.

After so much sweat trying to find the problem with the cruise and the OBC problem not showing the MPG and avarage speed. I can say confidentaly I can diagnose cruise control very fast.
E24 M6 Schwartz/Tan 3.8
E24 M6 Zinnoberrot/Tan 3.5
E24 M6 Royal blau/Dove. 3.5
E24 M6 Schwartz Track-Toy 3.6
E31 '97 840Ci Schwartz/black.
E30 M3 Diamond Schwartz
MinneapM635
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Getting Closer...

Post by MinneapM635 »

So, the weather has turned cold and salt is now on the roads here in Minnesota. That means the car is in the garage on stilts for at least the next 3 months. I decided today to take off the gauge cluster to "see what i can see". One thing I noticed right away... 1 two-wire blue plug and a one-wire green plug, not plugged into anything! This has got to be the reason why certain functions on my OBC don't work.

Two questions have arisen now...

1) Where do these plugs go, or what signals are needed for each of these connectors? I know it must have something to do with this cluster of available signals.

2) How can I determine if this cluster or all parts of the cluster are in fact the original ones installed in my car?

I get the sneaking suspicion that the speedometer/odometer cluster is not the original one for my car but am not sure how to tell for sure. For example, only 1 tab in the enclosed photo is broken giving way to the metal leads, but there are 2 plugs.

Thoughts?
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Post by ozbmw »

On my car those plug into the cluster, looks like someone has installed a new cluster and hasn't fitted all the wires.

The green plug is Volts and the blue is speed signal from memory.
Matt @ Snowy Mountains of Australia
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MinneapM635
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Post by MinneapM635 »

Well, the PO had mentioned that his son had fitted a new battery-less board or something or other to take care of the leaking SI battery issue. It's likely that he didn't reinstall appropriately.

Does anyone with an M635 have a picture of the back of their cluster so that I can compare?

Thanks for the info. That seems like a possibly fit for the two plugs. However, If I put both plugs in facing the same direction, I will get "masse" and "tempo (speed)" or "V" and "masse" based on which terminals are wired on the blue and green plugs.

Make sense? I gotta think speed is one of the signals, but if i orient the green plug in the same fashion, then the other signal will be "masse" which google translator was not able to effectively translate for me.
'85 "Arctic Blue" M635
'01 Silver 540iT Alpina tribute
m6csi

Post by m6csi »

The instrument cluster does look kind of dubious for an M635. If I'm not mistaken, isn't there a 535 stamped near the bottom or this may not indicate anything. Maybe this cluster could have been taken from a 535i. Suggest you do this as follows: Plug the blue connector to BLAU and plug the green connector to GRUN...you will have to snap off the white tab to do so. The plugs from your car do look slightly different than the ones fitted to the later cars.
Image

Here is a pic of an E24 cluster from the z3bimmer site showing the blue and white plugs connected to the module. According to this site, they are the odometer connections. My 88 M6 also has these colored coded plugs. The blue and white plugs maybe a North American model feature, whereas the Euro M has the blue and green plugs. Not too certain on this though.
Image

This may not help much, but this is the late cluster from my 88 M6. Just a slight difference compared to the earlier units, it has a black locking tab for the various connecting plugs.
Image
Chris Wright

Post by Chris Wright »

Someone went through this a couple of years ago, he couldn't figure out where the green plug went but finally figured it out. IIRC it was a Euro also. I did a quick search but couldn't find it, you might try a more thorough search?
MinneapM635
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Post by MinneapM635 »

Thanks for the pictures Bert. Yeah, I am not sure what the stamps mean, but it is at least a little reassuring that there are 3 pieces and all are stamped 4.85 which is the build month and year of my car.

At any rate, I am going to connect up the green and blue plugs as indicated and see where that gets me. This will give me the "masse" and "tempo" signals on the green and blue connectors, respectively.

It was nice to get the cluster out as I replaced 1 burnt bulb and also cleaned the inside of the clear plastic shield, which was a little grimy in parts.

I will report back if the plugs made any difference on the obc.

Thanks.
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clipper47
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Post by clipper47 »

Attached is a picture of the rear of my 1985 635CSi instrument cluster. Note the white plug on right and blue on left. I hope this will help you.
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Post by GazM3 »

i have exactly same problem.

on the OBC, time, date, temperature all work, so does timer.

items that dont work are, consumption (reads 0.0), distance to empty (reads always 345), ave speed (reads 0.0) Ill have a look at the motherboard as I have another insturment cluster here and ill have a look at the cruise control wiring. My odometer doesnt work also
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Re: OBC - some functions work, others do not

Post by panthercity »

@GazM3 wrote:
"on the OBC, time, date, temperature all work, so does timer.
items that dont work are, consumption (reads 0.0), distance to empty (reads always 345), ave speed (reads 0.0) Ill have a look at the motherboard as I have another insturment cluster here and ill have a look at the cruise control wiring. My odometer doesnt work also"

On my '85 Euro:
I had the exact same symptoms with my OBC described by @GazM3 above as well as the original poster. I replaced the MPH speedometer with a KPH speedometer that I purchased from a Canadian car and plugged the Blue wire back in to the slot marked "Blue" and it solved the issue. The OBC works 100%.

I also have a Green plug that was not been plugged in since I've owned the car and wondering if anyone knows what it is for? The slot to the left of the one labeled "Blue" is labeled "Green" and is currently blocked by a plastic tab. I presume that is where the green plug goes but have not broken off the plastic tab and plugged it in yet...There is also the slot to the right of the "Blue" slot labeled "White" that is currently empty. No White plug exists.


Regards,
Tony
'85 635CSi Euro
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