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Soft Touch trunk won't stay closed on 740iL
A while back I asked for help on a problem with my '96 740iL....the soft
touch trunk would pull it closed, only to open back up by itself, almost instantly other times by varying delays, some lasting up to minutes. Also once in a while it wouldn't open at all, even by pushing the release switch or remote control. Some people had told me to unhook the battery and let it "reset", others to unhook the battery, trip the latch manually with a screw driver, then reconnect the battery to fix it when it got "out of sync". Neither of these had any effect. The trunk electronics in my car were located in the A1 module located behind the glove box. It has four signals going to it: 1) Unlock trunk from inside the cabin (switch under dash by drivers door 2) Unlock trunk from push button on trunk 3) Motor closed position from switch mounted to rotating shaft that pulls it closed 4) Trunk open/closed signal from latch assembly mounted in the trunk lid, center (the part that fits over the pin). Turns out the problem was the switch in the latch assembly (4). It has dirty contacts and, depending on temperature and how many times it was cycled, as well as ornerienous, it would make or break contact. I found all this out by taking apart A1 and monitoring, with a scope, the signals coming into the box. It was obvious that the signal from that switch when closed was intermittent, not always staying grounded. (BTW, the signal is not a simple +12v or ground, but a recurring pulse put out by the computer that was held low (shorted out) when the switch was closed). The only way to get this switch is by buying the lock assembly. For sure it is fixed. Thanks again for everyone's suggestions and help ! JC -- Jim Collins Sammamish, WA |
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Soft touch close trunk on a 740iL inoperative | Jim Collins | BMW | 3 | October 4th 04 03:33 PM |