Procedure:
CAUTIONWhenever connecting or disconnecting the Motronic Control Unit the ignition must be switched OFF.
- Open vehicle glove box, remove upper black cosmetic cover, remove Motronic Control Unit.
- Verify the Control Unit Bosch number, 0 261 200 027, green label.
- Lay the control unit on the static mat facing down with the electrical pins pointing away.
- Unscrew four rear cover phillips screws and remove rear cover.
- Release the circuit board by unscrewing two slotted screws and two phillips screws. Note the position of the rubber and metal washers for correct reassembly
- Pull off rubber cone and fold out circuit board. Do not disconnect wiring.
- Remove EPROM from circuit board using the IC extractor tool.
Caution: Do not touch the contact pins of the EPROM
- Install the new updated EPROM using the IC inserter tool.
- The EPROM is correctly installed when the EPROM flat edge aligns with the IC socket flat edge.
- Some control units will have a 28 pin IC socket. When installing the 24 pin updated EPROM in a 28 pin socket, the EPROM flat edge must align with the IC flat edge. If this Important point Is not followed, the control unit will not operate and EPROM damage may result.
- Assure that all the EPROM contact pins are fully inserted by pushing down on the EPROM until the stop is felt.
Install the security cap on the EPROM.
Note: An unfavorable buildup of tolerances in the control unit circuit board can, in certain cases, cause the security cap for the EPROM to contact/interfere with the surrounding electronic components during installation.
If this situation is encountered, do not install the supplied security cap on the EPROM. Reassemble the control unit without the security cap.
The security cap will continue to be supplied at no additional charge.
- Reinstall the circuit board using two slotted and two phillips screws. The rubber and metal washers must be reinstalled in the same order noted during disassembly.
- Reinstall the rubber cone in the center of the circuit board.
- Reinstall the cover with four phillips screws.
- Affix label number 40 to the front of the control unit, next to the Bosch label.
- Reconnect the Montronic control unit to the vehicle 35 pin multiplug (ignition OFF) and perform a brief function test.
- Check engine starting, acceleration and idle quality. When correct engine operation is verified, reinstall the control unit in the vehicle.
- Check and adjust (if necessary) the exhaust CO/HC and the idle control valve current using the following procedure. See S.I. 13 03 88 (1589) for complete information.
^ Connect multimeter to ICV current probe.
^ Connect the BMW Service Tester and exhaust probes.
^ Start engine (oil temperature should be a minimum of 140~F/60~C).
^ Check current of the idle control valve with digital ammeter at the specified rpm as shown on BMW Service Tester. The current should be:
480 +/- 5mA at 700 +/- 50 rpm
^ If the mA and rpm readings are different from above, adjust idle control valve as follows:
1. Turn the adjustment screw on the side of the idle control valve clockwise (completely closed).
2. Slowly open the adjustment screw by turning counter-clock wise until 480 mA and the nominal rpm is reached.
Note: Do not turn screw too fast as you can easily overshoot the proper adjustment point.
^ Run Engine Test step 10 and assure CO adjustment is within specifications. If necessary adjust CO and then readjust milliamps and rpm to be within the above mentioned specifications.
^ Disconnect BMW Service Tester, digital ammeter and the ICV current probe.