Tuesday, March 27, 2012

96. BMW E36 18 Button OBC Retrofit

18 button on board computer (18 button OBC) is a great toy that you can easily install into your BMW E36. It doesn't really matter if you've already got another OBC, or you have the analog clock. As well, it really doesn't matter if you have a 4 cylinder or 6 cylinder engine. First thing's first - what kind of BMW on board computers are available?

Note: Click on the image for a larger view

1: 18 button on board computer (OBC)

2: Check control module with outside temperature and clock:

3: Check control module with digital clock:

4: Outside temperature and clock display:

All of the above listed units use special connectors. Units with less functionality have one connector. 18 button OBC has two connectors. Hopefully, you've bought these connectors (with some wire) together with the big OBC. If you don't have the connectors, you can build your own. (More on this later.)


Read the whole article before starting any work on your car.

Before working on your car, disconnect your battery. Wait for about 30 minutes for the system to discharge. You don't want your airbag light to go on, or even worse, the airbag itself. All information provided here worked for me, on my own car - 1996 316i sedan. Wire colors and component locations may vary according to model year and car specification. I do not take any responsibility for damages to your car and/or injuries you suffered following this DIY. Do It Yourself at your own risk.

List of components needed for 18 button OBC retrofit:

  • 18 button OBC unit
  • 2 connectors with some wire (one black, one white)
  • External temperature sensor
  • Gong (buzzer, chime)
  • Turn signal leaver with BC button (OBC Stalk)
  • Wires - a lot of them
Note, that only the actual 18 button display unit is really necessary. Everything else is optional.
If you need additional reference, original BMW parts are listed at the end of the article.

List of tools needed for the job:

  • Shrinking thermo tubes
  • Wire cutters
  • Wire strippers
  • Insulation tape
  • Screwdrivers
  • 16mm socket wrench
  • Torx 30
You'll need about 4 hours for the job. Beer breaks included. A quick summary of the tasks: Removing the steering wheel (and airbag, if necessary), taking out the instrument cluster, putting in new wires, replacing the turn signal leaver, connecting everything up, and putting the car back together...

Here's an photo of my new 18 button OBC vs. my old analog clock:

(The clock is upside-down... I know.)

List of connectors with codes

  • X1070 - Black connector on the OBC
  • X1071 - White connector on the OBC
  • X16 - White connector on the Instrument Cluster
  • X17 - Blue connector on the Instrument Cluster
So, let's get down to business.

DIY - Step by step

1. Remove your steering wheel.
There's some more information and pictures on removing the steering wheel in one of my older posts:

81. E39 to E36 Steering wheel retrofit DIY

2. Remove your instrument cluster.  There are two bolts at the top of the cluster. Remove the dashboard lower cover (under the steering wheel), and the plastic steering column covers.

3. If you have EWS, and want to use the CODE function of the OBC, then remove the glove box compartment.

4. Remove the analog clock (or the 'smaller' OBC unit), and the plastic panel under it - the one holding additional buttons (seat heating, asc, hi-fi...) and cigarette lighter.

So, by now, your car should look like it's ready for the junkyard. Here's a couple of photos for reference:

5. Prepare your OBC connectors. If you're lucky, you are doing an upgrade, and you already have one of those connectors. Since I was replacing my analog clock, I didn't have them. And to make things a bit more complicated, I only had one connector for my OBC. So, I had to make the other one. Here's how the back of the 18 button OBC looks:

According to the list of connectors, the black one is X1070, and the white one is X1071. They look similar to the ones behind the instrument cluster, but they are smaller. But, that's a good start - if you can't find the right connectors, you can source two connectors from an instrument cluster, and modify them. It might be a good idea to get a couple of extras, since you'll probably need some additional pins from them. So, a couple of images, so you can see what I'm talking about:

a) Rear of the instrument cluster - note the blue X17 and white X16 connectors:

b) The white connector from the instrument cluster - take it apart, and cut it to fit your OBC:

6. Replace your turn signal leaver with the OBC stalk. A fairly straight forward process. The old one just unclips from the steering column, and the new one snaps in.

7. Mount the gong (chime, speaker). It has five wires. They should be connected like this:
  • (blue/white) --> [X1070] Pin #10 (note: you can do this later)
  • (red/white) --> [X1070] Pin #11 (note: you can do this later)
  • (black/red) --> [X17] Pin #09
  • (brown) --> Earth (any brown wire)
  • (red/yellow) --> Old clock (red/yellow)
8. Mount the outside temperature sensor - it's usually mounted on the front bumper, in the left air duct. There are only two wires for the sensor. One that goes to the OBC, and ground. There should be a ground connection behind the headlamps.
9. Here's a list of the pins that you need to connect, for the 18 button OBC to work:
  • [X1070] Pin #06  --> [X17] Pin #26
  • [X1070] Pin #09  --> [X17] Pin #04
  • [X1070] Pin #10  --> Gong (blue/white)
  • [X1070] Pin #11  --> Gong (red/white)
  • [X1070] Pin #12  --> Temperature sensor
  • [X1070] Pin #13  --> [X17] Pin #02
  • [X1070] Pin #14  --> Wire under steering wheel (violet/white)
  • [X1070] Pin #15  --> [X17] Pin #24 
  • [X1070] Pin #16  --> Old clock (grey/red) 
  • [X1070] Pin #17  --> Old clock (brown)
  • [X1070] Pin #18  --> Old clock (red/yellow)
  • [X1071] Pin #01  --> [EWS unit] Pin #15
  • [X1071] Pin #04  --> OBC stalk (yellow/red)
  • [X1071] Pin #05  --> [X16] Pin #12 
  • [X1071] Pin #06  --> [X16] Pin #21  
  • [X1071] Pin #07  --> [X16] Pin #11
  • [X1071] Pin #08  --> [X1070] Pin #18
  • [X1071] Pin #09  --> [X17] Pin #10
  • [X1071] Pin #13  --> [X1070] Pin #17
10. A few notes:
  • EWS connector (if you have one, that is) is under the glove compartment box - it's purple. You need the #15 pin for the CODE function to work.
  • My car doesn't have the CHECK CONTROL module - so, I can't confirm that it will work. It should, but I can't guarantee it. In my next post, I'll show you how to disable CC on your OBC if you don't have one.
  • Don't forget to reassemble your car. ;)

Final result

Additional tech images


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