2003 E85 power top control issues

[pegasusactual]

I had the hydraulic pump replaced about two months ago, and it worked flawlessly for about four weeks. Now I have to manually unlock the top and pull it away from the windshield support before the controls will activate to lower it. It also stops about 1/3 of the way from being fully retracted, and the locks retract when they're approximately overhead. If I press the raise button, the locks will open. Then pressing the close button, the top will lower and lock into place. Raising at this point seems to be normal, but lowering has the same issue. It will work for and hour like this before the controls become inactive, and I have to manually unlock the top again.

To me it seems to be a position sensor issue, but I can't locate much information as to the sensor type and calibration method. Does the control module use a position sensor in addition to end travel limit switches for the top and locks? Is the position sensor something that has to be removed to replace the pump...could it be loose and have rotated? Could the control module be flaky?

Any information would be greatly appreciated.

Doug

[Shipkiller]

Google search is your friend:

http://www.bimmerforums.com/forum/sh...highlight=Hall

[pegasusactual]

Thanks for the link!

Given the symptoms what's your cursory diagnosis? I'm pretty sure my employer has a BMW service computer available, so i might try to connect to the control module. Presumably I'll be able to read the hall effect sensor voltage and calibrate the control if necessary.

[Shipkiller]

No calibration procedure is delineated in the TIS or in the BMW software (INPA or Rhiengold).

[gas-can]

If the top worked for a month after the change, perhaps one of the sensors was not tightened properly and now moved?

Another possibility could be a wire break in the hall sensor circuit. IIRC, the top uses 2 main position sensors for the open and close positions. Since the wires for at least one of these runs inside the folds of the top, it's possible that the wires, after a lot of operations, could have broken and are now intermittent. A bad signal here could give weird inputs to the computer...

It's easy to check this - I think 4 torx screws, 1 in the middle, and 2 on the side (with the top halfway open in the car) are all that's required to remove the plastic trim on the top. Look for the main wire bundle that runs to the driver's side of the car. You may need to open the wire guard to see the wires underneath.

See this article.

-gc

[pegasusactual]

Reading the position sensor from the BMW service computer reported that the top position was "implausible". Given that I had the hydraulic pump replaced about two months ago, I'm pretty certain that the mechanic didn't tighten the hall eeffect sensor and it rotated. Can this be remedied without removing the top?

[dc_wright]

Yes, both sensors are on the top rear of the driver side hydraulic lift cylinder. They're right at the hinge point of the top.