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1,000,000th Locking Post
BMW BMW General Discussions (alt.autos.bmw)
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#1
 
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1,000,000th Locking Post -
05-18-2007
, 09:28 PM
#2
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My fuel door mechanism will unlock, but won't lock. When I disassemble it, true to form, the motor only spins when I unlock. Does this mean the circuit isn't reversing polarity properly? If so, how does one test that? |
approx 12 volts when you lock and -12 volts when you unlock, or vice
versa. If it does, the fault is in the motor. If not, in the controller.
Alternately unplug and apply 12 volts from an external source. One of
those cheap jump start packs is very handy for this sort of thing. If it
runs in both directions when you reverse the polarity the motor is ok. If
it's a simple two wire system this rules out a wiring fault to the motor
so it must be either the controller or the control circuit operating it.
--
*A cubicle is just a padded cell without a door.
Dave Plowman dave (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.
#3
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In article <1179538114.658653.138... (AT) w5g2000hsg (DOT) googlegroups.com>, the_andrew_sm... (AT) yahoo (DOT) com> wrote: My fuel door mechanism will unlock, but won't lock. When I disassemble it, true to form, the motor only spins when I unlock. Does this mean the circuit isn't reversing polarity properly? If so, how does one test that? A DVM set to 20 volts across the line will show up a fault. It will read approx 12 volts when you lock and -12 volts when you unlock, or vice versa. If it does, the fault is in the motor. If not, in the controller. Alternately unplug and apply 12 volts from an external source. One of those cheap jump start packs is very handy for this sort of thing. If it runs in both directions when you reverse the polarity the motor is ok. If it's a simple two wire system this rules out a wiring fault to the motor so it must be either the controller or the control circuit operating it. |
I'll give that a try today.
a.
#4
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In article <1179538114.658653.138... (AT) w5g2000hsg (DOT) googlegroups.com>, the_andrew_sm... (AT) yahoo (DOT) com> wrote: My fuel door mechanism will unlock, but won't lock. When I disassemble it, true to form, the motor only spins when I unlock. Does this mean the circuit isn't reversing polarity properly? If so, how does one test that? A DVM set to 20 volts across the line will show up a fault. It will read approx 12 volts when you lock and -12 volts when you unlock, or vice versa. If it does, the fault is in the motor. If not, in the controller. Alternately unplug and apply 12 volts from an external source. One of those cheap jump start packs is very handy for this sort of thing. If it runs in both directions when you reverse the polarity the motor is ok. If it's a simple two wire system this rules out a wiring fault to the motor so it must be either the controller or the control circuit operating it. |
I press the lock.
I can only assume the fun begins now.
a.
#5
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A DVM set to 20 volts across the line will show up a fault. It will read approx 12 volts when you lock and -12 volts when you unlock, or vice versa. If it does, the fault is in the motor. If not, in the controller. Alternately unplug and apply 12 volts from an external source. One of those cheap jump start packs is very handy for this sort of thing. If it runs in both directions when you reverse the polarity the motor is ok. If it's a simple two wire system this rules out a wiring fault to the motor so it must be either the controller or the control circuit operating it. So, I get approximately 12 volts when I press unlock, but nothing when I press the lock. I can only assume the fun begins now. |
locking motor, so if this works ok it sounds like a wiring fault.
--
*I didn't drive my husband crazy -- I flew him there -- it was faster
Dave Plowman dave (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.
#6
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In article <1179617116.974203.184... (AT) h2g2000hsg (DOT) googlegroups.com>, the_andrew_sm... (AT) yahoo (DOT) com> wrote: A DVM set to 20 volts across the line will show up a fault. It will read approx 12 volts when you lock and -12 volts when you unlock, or vice versa. If it does, the fault is in the motor. If not, in the controller. Alternately unplug and apply 12 volts from an external source. One of those cheap jump start packs is very handy for this sort of thing. If it runs in both directions when you reverse the polarity the motor is ok. If it's a simple two wire system this rules out a wiring fault to the motor so it must be either the controller or the control circuit operating it. So, I get approximately 12 volts when I press unlock, but nothing when I press the lock. I can only assume the fun begins now. I've a feeling on some models this motor is in parallel with the boot locking motor, so if this works ok it sounds like a wiring fault. |
works properly.
I'll see if I can follow that thing back to whereever it goes. Maybe
I'll just buy one of my EE friends a beer.
a.
#7
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I've a feeling on some models this motor is in parallel with the boot locking motor, so if this works ok it sounds like a wiring fault. I did a quick test last night...the boot (we call 'em trunks) lock works properly. I'll see if I can follow that thing back to whereever it goes. Maybe I'll just buy one of my EE friends a beer. |
diagram of the period I have - I'd first look at the wiring round the
trunk hinge as the flexing can cause it to break. That does of course
assume the pickup point for the flap motor circuit is at the actual trunk
motor connector and not elsewhere.
Fixing this sort of fault requires good knowledge of the actual model as
wiring diagrams often don't help with the location of connectors etc. And
it's not unknown for the loom layout to alter during a model's life if
problems arise. Or that's my excuse if I've lead you up a blind alley. ;-)
--
*Time is the best teacher; unfortunately it kills all its students.
Dave Plowman dave (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.
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