Dismantling/re-assembling the Saab 9000 headlamp wiper motors


This procedure was carried out on a 1996 Saab 9000 Aero. Earlier (non-CS) models and pre-'95 CDs were fitted with a different motor.


The headlamp wipers on my 1996 9000 Aero had for some time been parking erratically. The final straw came one evening when I switched on the ignition, the windscreen washer pump started running and wouldn't stop until I switched off the ignition. Pulling various fuses isolated the problem to the headlamp wipers (the windscreen washer pump stopped running when the headlamp wiper fuse was removed). I removed both wiper motors to investigate and in the process, found that the right-hand headlamp wiper motor was the culprit. When I removed the motors for examination, this is what I found and how I dealt with it.

Time required

Having removed the headlamp wiper motors, I tinkered with them periodically over a period of time. I consider headlamp wash/wipe a convenience rather than a necessity. I'm sure I could have done the following work in an evening, but other people might come across different problems that may take longer to fix.

Tools required

The tools required will vary according to the problems found.

To gain access to the unit:

  • Small electrical (flat-bladed) screwdriver

To carry out my particular repair:

  • Small long-nosed pliers
  • Wire cutters
  • Soldering iron


  1. Unclip the wiring harness from the clip on the rear of the unit.

  2. Using the small electrical screwdriver, carefully prise each of the retaining clips on the backplate free. On the first unit, I broke a number of these, but the remaining clips were enough to hold the backplate on firmly on re-assembly. The small clips come free fairly easily, but the larger ones are very difficult to free.

  3. Remove the arm and plastic guide as shown.

  4. Pull the metal plate outwards as far as the spindle will allow and pivot it around the spindle to gain access underneath.

  5. If the motor was not self-parking properly, check the parking switch. This is a normally-closed switch that connects the motor to the permanent supply (red wire). The small gear opens this switch every five sweeps of the wiper, and when the switched supply (yellow wire) is removed, this stops the motor once it reaches the parked position. On one of my wiper motors, this switch was not making contact (the spring contact was bent). The result was that the motor would stop immediately the wash/wipe switch was released, rather than continuing to the park position. I removed the small gear and bent the spring contact so that it was just making contact and a bit more, then replaced the small gear, making sure it engaged properly with the switch contact. Don't bend it too far or the park position may end up being incorrect.

  6. The motor can be tested by connecting the black wire on the connector to 0V and applying 12V to the yellow wire. The motor should run while the yellow wire is connected to 12V. To test the self-parking function, connect the red wire to 12V, then momentarily apply 12V to the yellow wire. The motor should perform five sweeps, then stop.

  7. While performing the above test on my right-hand motor (they are both stamped "L" or "R") I saw the motor glow (presumably sparks) and issue smoke. There are two ways to tackle this and I have tried both:
    1. Run the motor off-load to clean the commutator and brushes
    2. Dismantle the motor and clean it
  8. Both methods require the motor to be removed. I did this by prising it up from the rear, taking care not to disturb the contacts around it. I did disturb the contacts and the square metallic plate marked (but not very visible) in the top photograph fell out. When replacing this between the copper strips, note that it goes in diagonally, i.e. one corner will be facing upwards when fitted. This plate connects the strips electrically, and is essential for correct operation.
  9. Running the motor off-load is the simpler method. I have had good results just by doing this. Simply connect a 12V supply to the two terminals and let it run until it is running at full speed and no more sparks are seen. Then reverse the connections and repeat in the other direction. This serves two purposes: it guarantees it has been driven in the normal direction without having to think too hard about it and also does appear to perform some additional cleaning since the sparks appear initially in both directions. This may be all it needs. If not, try dismantling it.
  10. Although the motor looks as if it is not designed to be dismantled, I weighed up the pros and cons: dismantle the motor and risk having to pay £100 for a new unit if I can't fix it, or give up and pay £100 for a new unit anyway. Needless to say, I had a go. When I first wrote this article the motor (Bosch part number 1-397-220-056) was still available but it was subsequently discontinued in 2014

    Once removed, I opened up the motor by prising up the retaining tabs with a small electrical screwdriver.

  11. The following requires great care and a degree of dexterity. Work in an area where you will be able to find small parts if they spring free.

    Withdraw the plastic end of the motor. This contains the graphite brushes. They are spring-loaded against the commutator and as soon as you withdraw this part, they will spring towards each other.

  12. Check the condition of the commutator (the copper contacts on the spindle). Mine was fine, but I had expected to find some burning, given the sparks and smoke I observed above. If there is evidence of dirt or burning, clean the commutator with very fine emery paper.
    I used a scalpel blade to remove graphite deposits between the commutator segments. Others have since reported that the graphite between the segments was alone sufficient to cause the sparks and smoke.

  13. Check the condition of the brushes. This was part of my problem! One of the brushes had rotated 90 degrees and instead of its curve following that of the commutator, it was now at 90 degrees to the curve of the commutator. This left very little contact area between the brush and commutator, hence the sparks and smoke. It had probably stalled in this position on the car, which is why it wouldn't park.
    This is where the manual dexterity came in. I had to carefully prise the two brush spring clips apart far enough to re-seat the brush into its spring clip.

  14. More manual dexterity: Carefully place the plastic end over the spindle until the brushes touch the end of the commutator. Then, using a small screwdriver (or something even smaller!) manipulate the brushes over the edge of the commutator. I managed to tilt the plastic piece slightly and work one of the brushes onto the commutator, then follow with the other. There isn't much of a gap to work through at this stage.

  15. I didn't bother to bend the retaining tabs back as the mounting arrangement for the motor keeps the plastic end in place. This should make it a bit easier to dismantle if I need to do it again.

  16. Reassembly: Refit the motor and the worm-drive.
  17. Fit the small parking gear with the flat part of the cam next to the copper contact, then gently rotate it anticlockwise until it stops against the end of the contact.

  18. Refit the other gears. The main gear must be positioned correctly to ensure that the park position is correct. Insert it so that the "L" or "R" is upright and the line marked on the gear is horizontal, as shown in the photo. The exact alignment is not critical but it needs to be approximately correct.

  19. Swing the plate over and press it firmly into place.

  20. Refit the metal arm and push the spindle back into place to engage its gear with the teeth on the arm.

  21. Refit the brown plastic guide.

  22. Refit the back of the motor. It may be as well to test the motor without pushing this fully home but keep some pressure on it while testing to keep the moving parts in place. Once satisfied, press the back fully into place, ensuring the clips engage fully all round the edge.

  23. Test the motor in the car. In my case, everything worked fine, except that the windscreen washer pump kept running until the RH headlamp wiper reached the park position. This tied in with the original problem (except that then, the RH wiper never DID reach the park position, so the washer pump ran all the time). Thanks to the reader who suggested that there is a diode in the wiper motor to stop current from flowing back out of the yellow wire (to the washer switch and hence to the washer pump) while the motor is parking. I may not have thought of it for ages, if at all! The diode appears to be sealed within the casing.

    Since it appeared that the diode had failed as short-circuit (rather than open-circuit, fortunately), I remedied the situation by cutting the yellow wire and placing a new diode in series. I chose a 1N5401 diode. It is rated at 3 Amps and 100V. I measured no-load motor current at 0.5A and by placing a load on the motor couldn't manage to get it to draw more than 2A. A 1N5400 would do as it is rated at 3A and 35V. I just happened to have the 1N5401 handy. I connected it with the cathode (silver ring indicates the cathode end) towards the wiper motor unit rather than the connector.

    The 1N5400 series diodes are an industry standard and should be available from just about anywhere that sells electronic components.

  24. After re-installing the motors, everything now works fine.