Adding an OBC to an E36 3-Series

UnofficialBMW.com Adding an OBC to an E36 3-Series

ADDING AN OBC
TO AN E36 3-SERIES

This is the second of a two part article on adding an OBC to an E36 3-series. The first part explained how to add European-style parking lights, which is a natural project to combine with this one since it shares much preliminary work and because the car needs a different turn stalk if you wish to use it control the OBC.

An On Board Computer (OBC) can be a useful and amusing accessory, and in many parts of the world you can order one on any BMW you might consider. In the United States, however, an OBC is often not an option until a car has at a least six cylinders. No doubt there are many owners of 3-series limousines, coupes and cabriolets who would like to have an OBC, an option that is technically feasible.

This article shows how to add an on board computer to a U.S. market, standard body E36 3er that did not come with one. The instructions have been checked against cars built in 1995 and 1996, but likely apply to early and later model years with possible modifications. The retrofitting requires some mechanical and electrical skill and probably should not be attempted unless you are comfortable modifying your car's electrical system. If the quality of the work is not at least as good as the factory's, you may have to pay for the consequences should something later go wrong. The job is not very involved, however, so the cost of having a journeyman do the work should not be too high.

These instructions assume your car already has an outside temperature display. They explain how to wire up an OBC to provide most of its basic functions, everything but check control, the CODE function, and parked car ventilation. Enabling these functions takes more effort. The adventurous can consult the Electronic Troubleshooting Manual for the appropriate year, chiefly section 6581.2. Be warned that the drawings have a fair number of errors and that it pays to compare ETM's for other model years and other markets. These instructions draw on the U.S. and German ETM's for 1995 and 1996.

As in previous article about parking lights, the information in this article has been segregated into two parts: a set of specific instructions for retrofitting an on board computer and a collection of more generally useful notes that explain the instructions. The notes are numbered, and the instructions cite them as they become useful as: $2.1, $2.2, .... To save space, the instructions also cite note's from the European parking light article as: $1.1, $1.2, ....

PARTS LIST

Quant.	Item
1	On board computer (GB/USA), BMW 65 81 8 357 684
3	Comb terminal contact sleeves for 0.35-0.5 mm² wire, BMW P/N 61 13 1 387 140)
1	Wire end with contacts for (brown) Siemens socket connectors, BMW P/N 61 13 0 005 201 (part of Repair Set H, Cartool BMW 61 9 058)
6	Wire ends with contacts for (black) AMP socket connectors, BMW P/N 61 13 0 005 197 (part of Repair Set H.)
1	18 pin AMP socket connector assembly consisting of: a black contact housing, BMW P/N 61 13 8 364 666, and an unkeyed water green strain relief shell, BMW P/N 61 13 8 364 662
1	OBC turn stalk that matches the car* (see $1.1)
1	wired 2.5 mm round male contact for 0.5-1.0 mm² wire*, BMW P/N 61 13 0 007 449

(*) You may omit the starred items if you do not wish to install an OBC turn stalk. The stalk allows you to cycle through the OBC modes as discussed in the owner's manual. A survey of BMW-digest readers found a nearly even split between those who really like such stock control and would add it to their next car and those who find it useless and would omit it.

Along with the usual tools, you will need a Torx T20 driver to remove the instrument cluster ($2.2), a long thin T10 driver to run wires to the fusebox ($1.12) and a 16 mm socket and a thin T25 driver to remove the steering wheel and airbag ($1.8).

PROCEDURE

1. Read out any DME fault codes and then disconnect the battery. BMW recommends you read the codes but this is not crucial.

2. Remove the outside temperature display ($2.1). Unclip the storage compartment underneath and push it to the right.

3. Remove the driver's kick panel and knee protection ($1.7).

4. Lift and unclip the black terminal/relay block on the front left wall above the driver's footrest (parking light article, step 4). Rotate the block so that you can add to its wires.

5. Remove the steering wheel and airbag ($1.8).

6. Remove the instrument cluster ($2.2).

7. If you are installing an OBC turn stalk, change the turn stalk and remount the four steering column connectors ($1.2).

8. Construct and lay the supplementary harness (later section and $2.5).

9. With the harness in place, move the following wires from the original temperature display connector to the new OBC connector:

Move	Wire Color and Function	To
X1070 pin 17	0.5 mm² brown ground wire	X1071 pin 13
X1070 pin 18	0.5 mm² red/yellow B+ wire from F31	X1071 pin 8

10. Reassemble connectors X1070 and X1071 and tidy up the wiring. The new X1071 connector is unkeyed and will fit the wrong socket on the OBC. To make sure of what it is going into, first plug the black connector, X1070, into the black, passenger side socket; then plug X1071 into the natural-color, driver side socket.

This schematic summarizes the conversion.

11. Clip the terminal/relay block back on to the left wall. Reinstall the instrument cluster, steering wheel and airbag ($1.9). Make sure no one is in the car and reconnect the battery.

12. Turn the ignition key to position one, the accessory position. A brand new, uncoded OBC will display P P P P. You now need to visit the dealer and make use of their DIS computer. First have the dealer run diagnostics on the OBC. You may see the following faults:

Central check control light
Gong T2
Gong T1
Code-Function
Timer
Terminal 50

All these “faults” are normal: the first if the car doesn't have check control, the second and third because you disconnected them, the fourth because you have not connected the drive-away protection, the fifth because the car doesn't have parked car ventilation, and the last, because you did not connect the OBC to the starter motor, assuming you constructed the suggested harness. (If you decide to add parked car ventilation or the CODE function, be sure to make the connection as shown in the ETM.)

13. If your wiring checks out, have the dealer code the OBC and place a new central code sticker under the back seat bench. A Meister may tell you that this is impossible. Actually, it is just a little uncommon, and a matter of finding the right menu. Then road test the OBC. At the very least, verify the CONSUMption, TEMPerature, SPEED and RANGE functions, and the turn stalk switch if you have added it. Once you are satisfied everything works, reinstall the knee protection, the diagnostic connector, the driver side kick panel with chimes and the steering column shrouds.

Enjoy your on board computer.

ACKNOWLEDGEMENTS

I would like to thank Thomas Fiebig (Bobrink GmbH), Allan Rhodes, Jr. (Bluegrass Honda/BMW), Ron Stygar and Terry Donohue for providing parts and practical information that made the OBC conversion possible.

SUPPLEMENTARY HARNESS

1. ADD A WIRE to X1070 pin 9 only if it missing. If you are adding parking lights or do not mind running a wire to the fusebox ($1.12), wire:

X1070 pin 9 A-------.5 mm² GN/BL------[ X1076

Otherwise:

X1070 pin 9 A-------.5 mm² GN/BL------* X17 pin 4

2. IF YOU WISH to control the OBC from the turn stalk, wire:

X1071 pin 4 A------.35 mm² BR/RT------R X32 pin 10

3. IN ALL CASES, wire:

X1071 pin 5 A------.35 mm² WS/VI---------------------[ X183
X1071 pin 6 A-------.5 mm² WS/SW------* X16 pin 21
X1071 pin 7 A------.35 mm² WS/GE---------------------[ X182
X1071 pin 9 A------.35 mm² WS/GR------S X17 pin 10

SYMBOLS AND WIRE COLORS:

A - AMP contact ($2.4)                    BL blue    RT red
R - 2.5 mm round male contact ($1.4)      BR brown   SW black
* - Splice to wire ($2.6)                 GE yellow VI violet
S - Siemens contact ($2.4)                GN green   WS white
[ - Contact sleeve ($1.11)                GR grey

COMPONENTS AND LOCATIONS:

X16 is the 26 pin, white connector you removed from the back of the instrument cluster; you will splice into one of its wires and possibly a wire going to connector X17.

X17 is the 26 pin, blue connector you removed from the instrument cluster; you will also add to it a wire with the one Siemens contact.

X32 is the 12 pin, white, male turn stalk connector ($1.5).

X182 and X183 are comb terminal junctions in the left wall relay/terminal block.

X1070 is the 18 pin, black connector that plugged into the passenger side socket of the outside temperature display.

X1071 is the new, 18 pin connector that will plug into the driver side socket of the OBC; it will take the five or six AMP contacts.

X1076 is a comb terminal junction in the fusebox.

NOTES

2.1 REMOVING THE OUTSIDE TEMPERATURE DISPLAY
mid removal

.
If you have a late model car, feel along the top of the storage compartment immediately below the display for a hole giving access to a compressible retaining bar. Press up on the bar to retract its ears holding in the bottom of the display, and while pressing, pull or gently pry the display out of the console. If you have an older car, insert a 1 mm feeler gauge or blade between the top of the storage compartment and the bottom of the display. Press the bar upward and carefully pry out the display. Unplug the rear connector as it becomes accessible ($2.3) and remove the display.

2.2 REMOVING THE INSTRUMENT CLUSTER

Remove the airbag and steering wheel ($1.8). Remove the two Torx-20 screws that secure the top of the instrument cluster to the top of its well. Gently pry down the top edge of the cluster until it comes frees, then slide it out. Be very careful not to scratch its soft, plastic face; clear plastic will attract all but the most carefully controlled tool. Unclip the instrument cluster's three connectors as they become accessible ($2.3) and remove the cluster.

2.3 UNPLUGGING HIGH DENSITY SOCKET CONNECTORS

The connectors are mated and separated with the aid of a swing lever. Press down on the plastic tab that juts out from the outer connector shell and locks the lever. Swing the lever over the tab and away from the vertical. Continue swinging until the lever is horizontal; then remove the connector. To plug the connector back in, start with the lever fully horizontal.

2.4 ADDING AND REMOVING HIGH DENSITY SOCKET CONNECTOR CONTACTS

To access the contacts, slide the black retaining clip off the end the wires exit; then gently pull on the wires and slide out the slim, rectangular contact housing. The contacts are numbered. They have retaining barbs which must be oriented so that they pop into the windows on the side of the housing; the contacts will then click easily into place. To remove a contact, use a straightened paper clip, gently press the contact barb through its window and slide it out. It should come out easily.

2.5 CONSTRUCTING AND LAYING THE WIRING HARNESS

Try to route the harness so that such things as the air conditioning can be removed without cutting wires. Someday, you may appreciate your foresight. You can use plastic ties to add to the car's existing cables or you can slip wires under the cable tape where it is loose. Don't worry about having some slack at the ends of the harness: you will have room and it is better than coming out too short. Try to use the indicated wire sizes and colors ($1.3).

You can now add wires. The contact locations are numbered and can be read with a bright light. To add a wired contact, find the correct position, thread the wire through the retaining shell and then click the contact into the contact shell. Remember: through the retainer; then into the shell. Don't forget or you may have to beg your dealer to lend you their contact removal tool.

2.6 SPLICING INTO EXISTING WIRES
splices

.
In the instructions they supply with their aftermarket products, BMW cautions: “Never use Scotchlock fast connectors”, as they may cause faults in low-level electronic signals. Here is a more compact and reliable way to splice into existing wires, for example, the B+ and fuel consumption wires running to the instrument cluster.

Find the wire you wish to tap into and unplug it from its connector. Unthread the wire from its harness back to the desired tap-in point. Using a soldering gun (but probably not its tip), melt through the insulation on both sides of the wire trying not to heat the wire very much. Bow the wire with your fingers and separate it from the melted insulation.

Using a fine diagonal cutters, pull back and trim away the melted and softened insulation so that you expose a short section of bare wire. Lay the new wire alongside the original, wrap it around the bare section, solder the connection and insulate it with heat shrink tubing or electrical tape (Fig. 2). Then plug the original wire back into its connector.