E30 M3 On Board Computer Replacement

catmundu · Apr 5, 2009

How difficult is it to remove the on board computer (obc) from the dash? i recently purchased my e30 m3 and the display on the obc is hardly visible or not visible at all at times. the previous owner gave me a new display unit with the car, it must have been on his to-do list and now is on mine! and p.s. i have not purchased the bentley manual on the car yet. thanks.

John in VA · Apr 5, 2009

I'm sure there are some tech tricks to replace the light bar - I look fwd to seeing them!
I don't know if the M3 differs from other E30 models, but I've done it by removing the radio and and stuffing my small hand into the hole to remove the rightmost pair of screws (there are 4 total, on each corner) holding the OBC in place. I was then able to pry out the right edge, pull out the white plastic light bar with a pair of needle nose pliers, and insert the new one. Don't drop the screws!
I also replaced one in a friend's E30 cabrio by removing the plastic panel on the left side of the glove box, then reaching back around the dash to access the screws.. Her radio was too complicated to remove.

mooseheadm5 · Apr 5, 2009

M3 is the same as others. In other words, a real PITA.

az3579 · Apr 5, 2009

I went through this PITA a while ago. Since you already have the 13-button OBC, you can ignore the bits about the wiring harness and such. You should only be doing the light bar replacement, so make sure you have a light bar handy and only do the following parts:
* Center switches and OBC
* Center console and handbrake surround (not required but will make your life a bit easier)

I did a full retrofit into mine (I had the 6-button one before) so I did a full writeup on it. It is as follows:

az3579 said:

After that post, I had to drop someone off (it was already dark) and I realized that I forgot to migrate the perfect bulb for the keypad lighting to the "new" OBC. Looks like I'll be doing this ALL OVER AGAIN TOMORROW.

Grant,
I have multiple coding plugs, but none of them are for a 318i. I do have one for an M3, though, but I wouldn't advise using it as the engine, fuel tank, and other things are different.
I have coding plugs for: E28 M5 or 535is (65 81 1 375 826), E30 M3 (65 81 1 381 792), E28 528e (forgot part # - currently installed, and I'm using this one now), and an E30 325i (65 81 1 381 793). If anyone needs any of these, let me know.

That coding plug that you have is for a 325e, but for a model with what I think is a smaller fuel tank. I do know that there was some kind of change between the early 325e models and my 87 because I have two different coding plugs listed for my build date 9/86, one of which is the earlier one (yours) and one that's later (ending 795).

Brian,
It's not really a hard thing to change the OBC, it just takes lots of time. I remember reading your article on iPod integration in Roundel and thought "boy I'd like to make an article - if I wasn't so incompetant". This project just requires you to be very careful, as you're dealing with old plastics and materials that can break easily.

A rundown of the swap (prepare a nighttime snack/drink and reading glasses as this will take a while):

The kit consists of the 13-button OBC (required),
* wiring harness (required) [not sure of part #]
* turn signal stalk with relay (optional) [keep in mind there is a separate stalk for cars with airbag and those without]
* relay (part# 65 81 1 373 726 - I have NO idea what this part does and have not installed it) (optional)
* new light bar (pretty much required - almost every OBC will come with a burned out light bar). You can get away with just buying a new bulb assembly as opposed to the whole housing + bulbs that I bought from BavAuto. Part # for the bulbs is: 62 11 1 368 299
and new bulb for the keypad illumination [standard 1.2W / 12V bulb you can find in the parts store]

I also recommend you change your center illumination bulbs "while in there", which are also 1.2W / 12V bulbs. You will need two of these.

I found that you do not need to remove the battery lead to do this swap. Nothing was harmed when I did it with the battery still connected.

Steering Wheel
You should begin by installing the wiring harness to set the stage for the swap. Begin by taking off the steering wheel (pry out the emblem in the middle if yours is so equipped) as this would provide easy access to swapping the stalk and taking out the instrument cluster. My steering wheel uses a 21mm nut, yours may be different. After you take the nut off but BEFORE you take the steering wheel off, mark the inside of the wheel and the steering column so that you could properly align the two when reinstalling.

Instrument Cluster
Once the steering wheel is off, you need to take out your instrument cluster. For this, you'll need to drop the kick panel surrounding the steering column by turning the (3) quarter-turn screws that hold it in place. This will provide you access to the two nuts you need to remove the plastic surround with. This is the surround that goes just above the steering column and under the instrument cluster. The nuts are located on the other side of this plastic piece, and there is one on each side of the steering column. To get a better idea of where they are, you will need to poke your head inside and look for two knurled silver nuts that are a PITA to remove (at least for me it was the first time I did it [I never put them back]). Once removed, just pop off this plastic piece to reveal some screws holding in the bottom part of the plastic surround that goes around the instrument cluster. Remove these screws (there should be 4) and look at the top part of this plastic, above the cluster. There should be two more screws, both at the top, that you need to remove. Once this plastic surround slides out, you will see the instrument cluster itself. There are two tabs, left and right on the top that you will see, that are held in place by screws. Take out the screws. At this point, I recommend you put some kind of cloth on the steering column to prevent scratching the cluster's front.

To pull the instrument cluster out, pull a little bit on the tabs so that they are dislodged from their positions and lightly pull forward and down on the instrument cluster so it tilts outwards. Once out, the faces of the gauges should be facing the steering column, with the connectors facing upwards and visible to you. Disconnect the three wiring harnesses (yellow, blue, and white) by using a screwdriver to push the black tabs up and pulling the connectors off. Instrument cluster is now out.

Center console and handbrake surround (not required)
This section isn't required, but will make life easier when trying to reinstall the center controls in the dash, and I recommend doing this as it is easy enough not to be a pain.

Start at the rear of the handbrake surround. Take out the rear ashtray and disconnect any lighting if applicable (mine wasn't connected). There is a plastic nut in there holding the surround in place. Use a 10mm socket to take it out. The whole surround slides a bit backwards, and to get it off you'll have to slide the handbrake boot off the handbrake. You might have to put the car in 1st, 3rd, or 5th gear to get the thing out as it will get caught in the shifter as you slide it forward. Once out, proceed to the shifter surround.

Pull off the shift knob and take out the shift boot and insulation if you still have it. Pry out the window switches by reaching in and pushing them out of their holes and disconnect the switches.

On either side of the surround, down in the footwells, there is a quarter-turn screw holding the surround to the center of the car (sorry for the lack of good description). Turn these screws and taken them out. Go back to the shifter area and take out the plastic nut in the shifter compartment. This also uses a 10mm socket.

At this point, you should be able to pull the entire surround back and up. Disconnect the cigarette lighter bulb and power wires and set the surround aside. Your center section should now look like a race car's, with only carpet left!

Center switches and OBC
This is where we get to the OBC. First, take out your old 6-button OBC by prying the plastic surround off the OBC with a thin flatblade screwdriver. Once off, you'll see two tabs on the top and bottom. Use these tabs to remove the OBC from the dash. Disconnect the wiring harness by flipping the black lever. Unfortunately, this will be the last "easy' OBC disconnecting; the 13-button one is a PITA.

Pry out and disconnect the top switches (rear window defrost, hazard, circuit breaker ('88 MY and earlier), and audio fader switches. There are two screws holding the plastic bezel in place, located in the top part of the second and fourth window-switch positions (from left to right). Use a flashlight and you will see them. They are small-headed but long screws. Take these out.

Removal of the radio is not necessary for the OBC swap, but if you have an aftermarket radio, remove the faceplate and bezel to avoid damage. If you plan on replacing the center illumination bulbs, then you must remove the radio.

Pull off the temperature control knob, the three slider control knobs, and the blower knob. Take a very thin flathead screwdriver and pry off the plastic cover that has the little drawings on it (for the HVAC controls, surrounds the three sliders). This will reveal four phillips screws. Remove these.

Under the entire HVAC control unit, there are two screws on either side (left and right) that, along with the help of clips, help hold the HVAC controls firmly to the center of the dash. If you removed the handbrake console and shifter console, then you did yourself a favor; look at where the top of the cigarette ashtray would be (you wouldn't be able to fit your head here if you didn't remove the consoles) and you'll see openings on the left and right. In these openings are the screws that hold the HVAC controls into the dash. Remove these screws.

At this point, the entire assembly should now pull forward, and by entire aseembly, I mean the assembly that holds the radio, switches, HVAC controls, and OBC. Pull this assembly forward so you could access the area where the OBC was installed. You'll notice the actual HVAC controls/unit should stay put, and only the plastic surround/assembly will slide forward.

Look where the OBC should be. You'll see a black plastic piece screwed into the plastic assembly. Remove these four screws and take out this plastic piece. You should now be able to install your 13-button OBC into that spot, using the four screws you just removed from that plastic bracket. Before screwing it in, this is the time to change the bulb for the keypad illumination in the OBC (you'll see the bulb holder on the back of the unit) and the light bar. For the bulb, just use some pliers and twist the holder and pull out. For the light bar, use the pliers to pull the white tab on the side of the unit. Take off the circuit board from the white housing and put in the new bulb bar (if you ordered just the bulb bar), or if you ordered the entire housing with bulbs like I did from BavAuto (65 81 1 375 461), then just pop that new badboy in.
Make sure you have the correct coding plug for your car, otherwise your range and possiblly mpg calculations will be off.

Install the OBC into the OBC spot using the four screws you removed the plastic bracket with but do not push the entire assembly back just yet. At this point, the wiring harness needs to be installed.

Wiring harness
Look for the wiring harness with the green connector that you disconnected from your 6-button OBC and follow it through its routing. You'll notice that the harness is held in place by zip-tie looking plastic that lines the inside top of the dash. Be very careful as this plastic is very old and it will break, like it did with me, so don't expect to reuse it. I used some velcro to hold the cable bundles together.

You'll follow the wiring harness until it reaches the instrument cluster section. The yellow connector that plugged into the instrument cluster is also attached to this harness. Take it out of the cable organization and keep following the harness to the left of the instrument cluster. At this point, I gave up in trying to take the old harness out because the next cable tie junction was way too far in and my hands were too big to fit in there. As a result, I just bundled the harness together, velcroed it and tucked it away so it wasn't in the way. If you do decide to go on, you'll see what I'm talking about. Once you get that "junction" to release the harness, continue down into the driver's footwell, where the harness continues. As I did not remove the old harness, I do not know what else this harness connects into, but it should be a temperature sensor connector (one or two pin, with a white connector housing). Here is a list of connectors on this wiring harness. This description is from strictlyeta.net's article on this procedure (http://www.strictlyeta.net/technical/obcretrofit.html):

BLACK CONNECTOR: Plugs into the right slot of the door gong and is used for low temperature and maximum mileage features.

GREEN CONNECTOR: Plugs into the fuel pump connector and is used for the CODE feature. Also supplies a feed to the auxiliary horn (which must be added); not necessary if you are don't want the feature active.

BLUE CONNECTOR: Plugs into the turn signal stalk and is used for the OBC remote control feature. If youd don't install the turn signal, then you don't need it.

WHITE CONNECTOR: Plugs into the ambient temperature sensor.

So, install your new wiring harness, routing it the same way that the old one was. The yellow connector should end up in the instrument cluster well, the green connector should end up where the OBC is installed, the white connector should end up in the footwell somewhere where the mess of wiring is, and the blue connector should end up there as well, under the steering column.

Turn signal stalk and relay (optional)
Remove the bottom plastic cover for the steering column by taking out the two screws holding it in. You should see these two phillips screws where the steering wheel would otherwise be covering it. The screw heads are facing upwards.

There are two more long screws holding the cover in place. Look on the bottom of the cover and you'll see a long horizontal opening. Look in here and you'll find your two screws. Remove these and the cover to expose the wiring for the turn signal stalk.

The stalk itself is screwed to the steering column by two screws that you'll see when you remove the cover. There is an additional screw that is used to screw the grounding wire to the column, which you will also see. Unscrew these screws and remove the turn signal stalk, disconnecting the connector with the brown/yellow wiring (maybe your colors will be different). This is a "you'll see when you do it" section. You can leave the relay attached to the turn signal stalk (black box) or attach it to the "new" one if it doesn't have one. They are the same part number. I used the new stalk's relay because the sound was slightly different, deeper. I liked it enough to use the new one!
The old stalk will have a wiring harness that connects into the white plastic assembly of connectors that are attached together. You'll see when you do it. The way you "disassemble" this plastic orgy of connectors is by sliding them on or off (they don't "detach", they slide). Once you slide off all the connectors off from each other, remove the stalk along with harness. Install the new stalk with harness the same exact way in reverse order as you removed the old stalk. There is an extra connector though (blue) that you will plug into the blue connector in the OBC harness that you dropped down.

Now's the time for you to install that black box relay I mentioned earlier (I have no idea what it does). I do not know where it mounts and I do not know what connects into it, so you're on your own here.

Once everything's connected with the stalk (be sure to screw in the grounding wire where the old one was screwed in!), you can reinstall the steering column cover.

Now's the time for you to install that black box relay I mentioned earlier (I have no idea what it does). I do not know where it mounts and I do not know what connects into it, so you're on your own here.

Reconnecting everything
Now that the harness is in place, you can reinstall the instrument cluster, plugging in the white connector, blue connector, and the new yellow connector from the new harness. Installation is reverse of removal, and take special care not to break off the mounting tabs from the cluster. Try to install the cluster the same way by tilting it back in. You will have to play with it for it to go back in properly. You will also have a very hard time reinstalling it if the plastic zip tie things broke off inside, because the wiring harness must be routed above the cluster for it to fit properly. If the plastic ties break off, good luck trying to mount the harness to the top. I used velcro to hold it up while I installed the cluster. You can put back all the screws and trim except for the black plastic cover that goes right over the steering column. Install this last.

Please, please, PLEASE test the lighting to make sure everything works properly. Turn the key to ignition II and test the functionality of the OBC and turn on the lights to make sure your light bar lights up and the keypad illuminates.

As for the center controls, you can push the entire assembly back, making sure to line up the HVAC sliders into their "tracks". If you want to install new illumination bulbs, do it before you push everything back. One bulb is located on the bottom right in plain sight, and the other is located just under the radio on the left. If you do these bulbs, you will have to remove the radio to get to the left bulb.

When pushing the entire control assembly back, make sure to have the sliders for the HVAC controls correctly line up in their "tracks" with the plastic bezel because otherwise you won't be able to push the plastic assembly back properly. When the sliders properly stick through the plastic bezel, put back the four screws that you removed. This will hold the entire thing together and keep it from falling apart on you. While pushing the assembly back, take care not to allow the connectors for the hazard switches etc. fall in behind the radio, otherwise you'll never get them out without taking it apart again. Reinstall the two bottom screws that you can only see from the shifter area, and then the two thin and long screws along the top of the bezel (remember, 2nd and 4th switch positions). Reinstall all switches and reinstall the faceplate for the HVAC controls before putting back the control knobs. If there's anything I forgot, reinstall it.

*phew*

Brian A · Apr 5, 2009

There is also a link to some instructional photos in the following thread:
http://bmwcca.org/forum/showthread.php?t=1227

catmundu · Apr 5, 2009

thanks guys! y'all are awesome. deep down i had a feeling it was going to be a PITA. but hopefully from pain, will come a functional obc! i plan on doing this over the long weekend next weekend- will keep u posted.

03BeastCharmer · Apr 6, 2009

catmundu said: ↑

thanks guys! y'all are awesome. deep down i had a feeling it was going to be a PITA. but hopefully from pain, will come a functional obc! i plan on doing this over the long weekend next weekend- will keep u posted.

We are?????
I guess I better read up!!! Or let you and your small hands handle this one

catmundu · Apr 6, 2009

BUSTED!!!! lol i was gonna tell u about it.....saturday.

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E30 M3 On Board Computer Replacement

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