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2004 XLR - Folding Top Module - B3669

xlrlist01

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Oct 31, 2013
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It sounds like the trunk lid is not being released. Does the lid sort of swell up near the tonneau cover? If so the hydraulics are working fine, but the trunk release isn't releasing (press the remote again to stop the pump). If you use the key in the rear slot, it mechanically releases the latch, and if all is working correctly, the deck lid will lift on the hydraulics.
There is a known fault reported on this site where the signal from the BCM to the latch fails. It is caused by corrosion on one of the plugs (harness ends) at the BCM. Only unplug after the battery has been disconnected, and always open the doors before you disconnect the battery (so you can get in!). There is a plug with a grey/blue top, that runs (from memory) 'vertically' in the BCM (it is C2). Release the catch (it rotates and separates the two halves of the connector as it swings open) and look at the bottom pins (nearest where the wires come out of the connector). Apply contact cleaner (not WD40) and see if that fixes it. The pin next to the trunk deck release is linked to the brake pedal position sensor and if the corrosion spreads to that pin, you get errors to do with brake pedal position and/or brake lights on when you are not braking.
This has all been discussed on this site before, though not for many years.
Also, from memory, the workshop manual (2004 edition) has many errors concerning the release of the trunk deck lid. The BCM is shown as using C1, pin 71 (BN/WH) circuit 2091 to release the deck lid, however the circuit is light green and possibly comes from C2, pin 36 (which is shown as unused). C2 pin 18 is the 5V reference for the brake position switch and if my memory serves, those two pins are next to each other. The release circuit is not shown in the schematics (a clue that there are problems with the workshop manual).

Running through the manual BCM C1 pin 1, not used, 19 is fog lamp relay, 37 is not used and 55 is the serial data (class 2). The other end of C1, pin 18 is trunk ajar (OG/BK circuit 744), 36 is not used, 54 is not used and 72 is not used.
C2, pin 1 is serial data, 19 is serial data, 37 is not used and 55 is not used. Pin 18 is brake position as above, 36 is not used, 54 is not used and 72 is not used.

As these do not align with what is fitted, again from memory the release system as designed when the manual went to print was replaced by a much more simple release signal which simply interrupts a continuous 12v signal (which causes it to go to zero because the latch is monitoring it), and the latch releases the deck lid.

You have to admire the workshop manual for 'folding top does not open'. Operate the top, does it open? No - go to step 3. 1. Use scan tool yadda, yadda. 2 operate the folding top so the decklid is in the full extended position. 3, 4. Does the scan tool parameter display active? If no, go to step 7. Well, with the decklid jammed closed, good luck! It goes on about the switch being defective (step 7 and others), but you know that isn't the problem because the pump runs.

HTHs.
 

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