E30 Electric Tops

Realignment procedure

Source of power top failures

Another successful power top repair, with several hints

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A broken motor is a common problem with the E30 power top. Until recently, if your power top motor broke you only had two choices, to replace the broken motor ($500-600) or convert to a manual top.

Top motor re-sync procedure>>

To the left of the motor that controls the top (far right motor) there is a black control box that has (4) relays (coils). Check these (4) coils with a 12v tester for power with the ignition key on. If all of these have power then it is possible to get power to the micro switches. If these relays do not have power, then you'll need to either swap out the control box or troubleshoot the wire harness by doing some continuity checks.

The reason the top does not work is because there is no power to the micro-switches, I'll explain.

Power to the micro-switches is controlled by the lid motor lock mechanism. The lock mechanism is controlled manually by the allen wrench. When the lid is locked and the lid motor engaged the switches will have power (you'll notice that when you lock the lid, the lid motor assembly swings in and out slightly). When the lid is locked it swings the motor closer to the body of the car and completes the ground for the micro switch. The problem is, it is very difficult to get both the lid locked and the lid motor engaged. They must be done simultaneously. If you have power to the relays, here is how to get power to the micro-switches.

This is easier with two people....also make sure the ignition key is on

Disengage all the motors (unlock the lid mechanism, disengage the lid motor and the top motor)

Undue your top from the front window and push it up like your going to put the top down with the switch

These have to been done in this order.

Re-engage the top motor (far right) have someone slowly lift the back window until you can seat the top motor in.

Now the hard part...

You have to lock the lid mechanism with the allen wrench and engage the lid motor at the same time. It took me several tries at this. Try locking the lid half way, then pushing in the motor half way and play with it until the motor pops in and the lid locks at the same time.

If you were successful you can turn the micro switch adjustment screw (located to the left of the allen lid lock point). When you turn the adjustment screw you'll hear a click when the switch turns on or off, you'll have to listen carefully. If you don't hear a click then you have to disengage the lid motor and unlock and try again. If you do hear clicks while turning the adjustment screw, turn the screw all the way to the left and slowly turn to the right until you hear a click. Then test your top, does it work? If not turn the screw all the way to the right and slowly turn to the left until you hear a click. Then test your top again, it should work and may require further adjustment using this adjustment screw.

This is a difficult procedure to explain, but it is fairly easy to do yourself. The micro-switch will not get power if you are unable to lock the lid and engage the lid motor simultaneously. My dealer could not even do it. So it will take some playing around with until you get the feel for it. Once all the motors are engaged and there is power to the micro switches you just have to turn the lid micro switch to the position the tells the system the lid is down and locked. Then the top should operate normally.

Source of power top failures?

Magnus posted a message that provided an excellent description of an investigation into power top motor failures. He presents a theory and provides data to support that theory. Here's the content of his message:

This is to inform about a common breakdown of the E30 top motor mechanism. Up to now, we (three E30 convertible owners in Europe) are aware of four cars (including our own cars) that have had the very same top motor mechanism breakdown. Therefore, we decided to share our experience, hopefully to prevent at least some future breakdowns and to hear other owners' experiences.

The BMW E30 convertibles came with three different top maneuverings, the manually operated top, the electro-mechanical (EM) operated top, and the rarely seen electro-hydraulic (EH) operated top, originally found in M3 Cabrio. This experience concerns the EM operated top usually found in the 318ic – 325ic as option.

THE SITUATION

The pivot which fixes the lever (54 34 8 112 788) on the light metal casing of the gearbox of the top motor (54 34 8 106 979) may break (see picture at Keith's site http://www.e30ic.com/powertop.htm). Since the casing is not sold separately this breakdown requires renewal of the entire top motor (54 34 8 106 979) with gearbox, which costs about $500 (labor cost not included) or using the German repair kit.

After this breakdown occurred on my car as well as a friend's car, we decided to investigate our cars and eventually we found the probable cause of the breakdowns. Our cars (325ic made 1991) seem to have a "bug" in the control unit (61 35 1 394 205), which coordinates the top and lid motors during operation. We do not know which VIN numbers that carry the bug (if not all EM top cars). Up till now, we are aware of four cars (made 1991 and 1992) that have had this top motor breakdown. All of them carried the bug in their control units.

The bug is activated only under certain circumstances when one stops the opening (or closing) sequence and then continues the sequence again. Thus, one can avoid activating the bug if one knows when it occurs. In order to explain when and where in the opening and closing sequence the bug is activated, we first need to define the stages of the power top opening and closing sequences.

THE SEQUENCES OF THE POWER TOP

The top and lid are controlled by two electrically driven motors, the top motor (54 34 8 106 979) and the lid motor (54 34 8 106 927), whose running sequences are controlled by the electronic control unit (61 35 1 394 205) in order to coordinate the top and the lid during opening and closing of the top. In short:

The opening sequence

After unlocking and pushing up the front of the top by hand, pressing the switch on the dashboard to open the top will begin the opening procedure

Stage 1 Top motor starts and real bow of the top-folding frame is raised
Stage 2 Top motor stops and lid motor starts
Stage 3 Lid opens
Stage 4 Lid motor stops and top motor starts
Stage 5 Top opens
Stage 6 Top motor stops and lid motor starts
Stage 7 Lid closes and locks
Stage 8 Lid motor stops
The closing sequence
Pressing the switch on the dashboard to close the top will start the lid motor.
Stage 9 Lid motor starts and lid opens
Stage 10 Lid motor stops and top motor starts
Stage 11 Top closes
Stage 12 Top motor stops and lid motor starts
Stage 13 Lid closes and locks
Stage 14 Lid motor stops and top motor starts
Stage 15 Real bow of top folding frame is lowered
Stage 16 Top motor stops at top-closed-position
Pull down the front of the top manually and lock.
THE BUG

It is well known that the operation can be stopped at any of the stages above. After stopping, the sequence can be continued (in any direction) by pressing the switch again.

The bug is activated only when one starts the power top after it has been stopped at stage 3 (or 13) above, i.e. when the lid motor is running and the lid is opening (or closing) behind the maximum raised rear bow of the top-folding frame. Whenever the sequences are at any of the other stages, the power top can be stopped and started again without activating the bug.

To come to the point, if one stops the sequence at stage 3 or 13, the lid certainly stops. The bug is activated exactly when one presses the switch on the dashboard again to continue the sequence (in any direction) from any of these two stages. What happens then is that there is current supply to the top motor(!) for about half a second and the top motor axis is turned app. 5 degrees clockwise beyond its end position such that the (already maximum raised) real bow of the top-folding frame is pushed with stress against its end position. Half a second later, the lid motor starts and everything continues as expected. Normally, you never recognise this half-second-longing initial movement of the top motor, unless you watch its axis or measure the current supply to the top motor just at the moment when you press the switch on the dashboard to continue the sequence.

Thus, any time the power top is started from stage 3 or 13 above, the top motor receives this initial current impulse and the rear bow of the top-folding frame is pushed with stress against its end position and, via the gearbox, the top motor delivers great torque. It is now lever (54 34 8 112 788) that ALONE has to withstand the torque of the top motor. However, it is the pivot on the light metal casing of the top motor gearbox, which fixes this lever (54 34 8 112 788), that breaks by time.

We also had a look at the fraction surface on the casings. In all four cases, the pivot was torn away in that direction, which is expected when the bug lets the top motor run clockwise outside its range to a position, which it should never reach. This suggests that the bug has caused the breakdowns, at least on those four cars we have seen.

We took one of the damaged light metal casings to a welding firm, specialized in light metal alloys. They tried to weld it, but the light metal alloy in the casing contains too much zinc to be weldable. Hence, one needs a new casing. It is too bad that the BMW dealer does not sell the casing separately but only the complete top motor (54 34 8 106 979) with gearbox (app. $500). However, there is German company selling a repair kit for the casing for about $150. It can be found at ebay from time to time.

CONCLUSION

DO NOT STOP THE OPENING OR CLOSING SEQUENCE AT STAGE 3 or 13 WHEN THE LID MOTOR IS RUNNING UNLESS YOU HAVE TO - THIS WILL ACTIVATE THE BUG WHEN YOU CONTINUE THE SEQUENCE AGAIN!

The only exception to this is of course if there is something obstructing the movement of the lid. Then one has to stop to prevent damages.

Whenever the power top is at any of the other stages, it can be stopped and started repeatedly without activating the bug.

EPILOGUE

A common problem with the EM power top stems from the fact the motors are relatively powerful and if something results in an obstruction of the top or lid during operation (e.g. wrong operation, bad lubrication or inadequate adjustment), the force of the motors may be sufficient to cause damages on the top-folding frame or lid mechanism. Consequently, four essential conditions seem to be conclusive for a well functioning power top:

1. The power top system is properly operated
2. The power top system is properly maintained
3. The power top system is properly adjusted
4. Avoid activating the "bug" at stages 3 and 13 mentioned above (pivot on casing may break as described)

As long as these four conditions are satisfied, there should be very few problems with the power top. Our experience is that the common damages of the E30 power top system trace back to a repeated neglecting of at least one of the four conditions.

/Magnus