This Tech Tip is from THANKS!

Resetting the service interval indicator lights on BMW E30's and similar

You'll need a piece of electrical wire (10/15 cm) to serve as a jumper wire.
According to Patrick Farrel, a BMW master tech working at a dealer in MD, you should always use a fused jumper wire.

First, locate de diagnostic socket, at the engine compartment.
There are two different types: up to 1987, it's located near the intake manifold, and has a red cap:

Early type connector

After 1987, you have to find a big round black plastic socket, with a cap held by a plastic strap, located near the oil dipstick (M20 engines) or near the firewall, driver's side (M40 engines):

Late type connector

Pull the cap (early connector), or unscrew it (late connector), and you'll see a number of connectors, depending of the type of plug (see the diagrams below).

Early type connector late type connector

  • According to the type of plug on your car, locate the right connectors, marked red in the diagrams;
  • Use the jumper wire to connect them together;
  • Turn the key to ON position, without starting the car;
  • When the 5 LED's in the dash light up (3/4 seconds), turn off the key. If you keep the ignition on, another 6/7 seconds, after the LED's appear, you'll perform an inspection reset, too.
  • Disconnect the jumper wire.

Be Carefull! Make sure you jump the right connectors! The best way to follow the diagram for the late type connector is to match its center circle cut (that looks like a pacman :o)) with the one in your car. The earlier one has a flat side, so it's easier to follow.

If you can't reset the lights, or if they reset and return after a few days, you probably have to replace the SI board batteries. Click here to read more at

Here's another reference on the reset tool

Section 19.6: Resetting service indicator lights

Most people I know think the BMW service indicator light cicuit is totally useless. However noone wants the damn lights on all the time and some people (like me) like to keep everything working. So here's a file I've been compiling on the subject. I've not check this on early model (pre '88) cars but it's accurate for the later models. I've also not given credit for some of the material because I forgot where I got it. Anyway here it is:

BMW Service indicator lights FAQ.

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The service indicator lights are reset through a pin in the diagnostic connector located in the engine compartment.

There are 2 types of diagnostic connectors used on BMWs. One is a 15 pin connector used on 1987 and earlier cars, the other is a 20 pin connector used on 1987-on cars. In what follows the 15 pin connector is referred to as the early type and the 20 pin as the late type. Resetting the service indicator lights is described below. The most common problem with resetting the service lights is bad NiCad batteries in the instrument cluster. The batteries seem to fail pretty consistently after 4 years.

The symptoms of this are:

1. The inspection light comes on.

2. Resetting the light according to the instructions below either doesn't work or works for a short period of time and then the inspection light comes back on.

The fix for this is to replace the batteries as described below.

Relevant Roundel references:

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The Roundel is the monthly publication of the BMW Car Club of America.

Jan 1992, Nov 1991, Dec 1989, May 1988 -- Resetting the service indicator lights

Nov 1991 -- Replacing the Nicads.

Resetting the service indicator lights.

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Late type connector:

The service indicator lights are reset by connecting pin 7 to pin 19(ground). The proper way to do this is to have the ignition off and place a jumper wire between pins 7 and 19 (make sure you get the right pins!). Then turn the ignition switch to position 1 (accessory), when the service light goes out, turn the ignition off. The difference between resetting the oil service light and the inspection light is in the length of time you have the jumper in place with the ignition on. This means that if you are resetting the oil service light, you should turn off the ignition immediately after the light goes out. If you leave the jumper in too long with the ignition on, you will perform an inspection reset as well and the next service indicator will come up as an oil service rather than an inspection.

The service light reset tools that I have seen connect to 3 pins of the diagnostic connector: pin 7,14 and 19. The connection to 14 is to power the tool. The less sophisticated tool has only one switch that connects pin 7 to 19. While those pins are tied together a red LED blinks to measure time. You count blinks and manually turn off the tool after the appropriate number of counts for oil or inspection reset. The more sophisticated tool has two switches, one for oil reset, one for inspection. It must have a built in timer that jumps pin 7 to 19 for the correct time.

Early type connector:

The procedure is the same as above, but you jumper pin 7 (the service indicator pin) to pin 1 (the ground pin).

The early type connector:

The early type connector:

                    ****       ****
                 ***      (10)      ***
               **  (9)          (11)  ***
              *                         *
             *          (2)             *
            * (8)               (3)     *
           *                            *
           *       (7)                  *
           *              (1)           *
           *                      (4)   *
           *                            *
            *        (6)                *
             * (15)          (5)        *
              *                         *
               **  (14)         (12)  ***
                 ***      (13)     ***
                    ****       ****
Diagnosis plug connections:

No.     Terminal        Designation
1       31              Ground
2       -               -
3       -               -
4       FT              Temperature gauge
5       L               Engine M10B18 Interfrator output for CO adjustment
                        Engine M30B34 Oxygen Sensor signal
6       A               Diagnosis lead for SRS
7       SI              Service indicator
8       P+              Position sender
9       S               Shielding
10      P-              Position sender
11      50              Starting pulse for starter
12      61              Alternator charge indicator
13      1               Ignition signal
14      30              battery +
15      15              Power supply for ignition

The late type connector:

                        **   ***
                    **** *****  ****
                 ***      (1)       ***
               **  (12)         (2)   ***
              *                         *
             * (11)    (20) (13)    (3)  *
            *                             *
           *  (10)  (19)       (14)   (4)  *
           *                               *
           *                   (15)        *
           *  (9)    (18)             (5)  *
           *                  (16)         *
            *            (17)             *
             **   (8)             (6)   **
               **                     ***
                 ***     (7)       ***
                    ****       ****

     Pin    Wire Size   Wire Color   Circuit and Component Connected
    -----  ----------- ------------ ---------------------------------
      1         1          BK        Ignition Coil, Motronic Control Unit

      6        0.5       WT/BK       SRS Connector (Not Used)

      7        0.5       WT/GN       Service Interval Indicator, Service
                                     Interval Processor(Reset).

     11        2.5       BK/YL       Starter, Start Signal(50)
     12        0.75        BU        Charge, Alternator(D+)
     14        2.5         RD        Battery
     15        0.5       WT/YL       Motronic Control Unit(RXD)
     16        1.5       GN/WT       Oxygen Sensor
     18        0.5       GN/BU       Motronic Control Unit(Programming Voltage)
     19        1.5BR       BR        Ground Distribution(G103)
     20        0.5       WT/VI       Motronic Control Unit(TXD)

The Dummy plug.

- ---------------

Late models:

The cap on the diagnostic connector is actually an electrical connector that shorts together the following pins:

- --pins 18 and 20 to pin 19.

- --pin 14 to 15.

And here's another....

Subject: Re: Reset Tool

Years ago on my E30, I was one of the first persons to realize that grounding pin 7 of the diagnostic connector would reset the service lights. I found that grounding pin 7 for ~3 seconds applied to an oil reset and that ~9 seconds applied to the inspection reset.

I made up a wire jumper using a copper Mueler alligator clip and banana plug (male pin) that would accommodate the diagnostic female pin. Rather then short the two pins within the diagnostic connector, I decided to attach the alligator clip to engine ground and connect the male pin to diagnostic pin 7 (less chance for error). I also embbeded a 500 ohm resistor in series within the banana plug. This limited the current to ~25 ma. in case you went to the wrong pin. As a side note, the reset on an F100 jet engine diagnostic unit is defined as 50 ohms or less to ground. I made a bunch of these for people that didn't want to be bothered making their own. I still use one to reset the lights on my Sweethearts '84 528e.

I'm two lights away from a BMW oil service on my ti. I plan on designing a similar (in concept) item for it and my 328. On the newer cars it appears that you have to provide the short and then remove it, after some time, to reset the lights. Looking in to this, is on my things to do list. Will write up a how to, when I'm done.