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#1
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1983 300CD: What is the part in the attached picture (behind the glove box)?
I am *STILL* trying to kill the ground fault that drains my 300CD-T's battery. Thus far, I have traced the problem to the circuit that includes the part that is is shown in the attached picture. The part is located behind the glove box and attached to the firewall (essentially). It has one electrical connector (the type that is on the brake fluid reservoir) and two vacuum connections.
I'd sure appreciate it if someone will tell me what this part is. Searching my manuals and other resources still has me in the dark. Thanks- Last edited by dogguy; 05-19-2010 at 09:52 PM. |
#2
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Perhaps that is the valve for the backrest locks?
-Jason
__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket Tesla Model 3. 205,000 miles. Been to 48 states! Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels. 2014 Cadillac ELR 2013 Fiat 500E. |
#3
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Isn't that part of the HVAC system? I'm about to leave work or I'd check the vacuum diagrams. I think that attaches to one of the pink pods that are part of the HVAC system.
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#4
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This is a distinct possibility because I think that the middle vacuum connector has a hard plastic blue (indicates backrest locking system) line attached to it. I can't be certain however, because the access (until I remove other things) is awfully tight there and I can barely see up to the actual point of connection. Looks like blue, however.
Regardless, this is the part that distinctly "CLICKS" when either door is opened or shut (as a result of the door jamb courtesy switch being activated/de-activated). |
#5
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Got it!
From the M-B "Electrical Troubleshooting Manual", page 135:
"SEATBELT LOCK SWITCHOVER VALVE". Now, I wonder if it is W0133-1617610 from FastLane (no picture available). It is referred to on FastLane as a "Vacuum Change Over Valve" and an "Elect. Change Over Valve". $52.00 is probably about right...Anyone have any ideas if this is indeed the part? |
#6
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That sounds like the right part. It is a switchover valve. Electrical signal will tell it to switch functions (hence the 2 vacuum lines and a vent).
Make sure when you reinstall the new one, you know which one goes where.
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http://farm8.staticflickr.com/7271/7...144c3fc1dc.jpg |
#7
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I hope you are not buying a new valve. How do you know the old one is bad? You need to trouble shoot it more.
__________________
85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
#8
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I have discovered that this valve (powered through fuse 2) is consuming battery energy when either or both doors are open and the ignition is completely off (and the front courtesy light is manually set to "off" for that matter). An easy way to determine this is to turn the ignition completely off, turn the courtesy light off, open either or both doors, place one's hand on the valve, feel the unit quickly become very hot, and watch the VOM display the battery current drain.
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#9
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Since yours is a coupe, it is part of the front seat locking mechanism that's linked to the door jamb switch. If the doors are open, this switch triggers to allow the operator to tilt the front seats forward (unlock them) so passengers can get into the back seats.
Once the doors are closed, the valve deactivates since the door jamb switches are off and the seats have been locked into driving position. It makes sense, but I am not 100% sure if this is how it's supposed to work since I've never owned a coupe before.
__________________
http://farm8.staticflickr.com/7271/7...144c3fc1dc.jpg |
#10
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Quote:
In comparing my problem with the same operation on a 1985 300CD-T, I have NOT found that this valve draws current when everything else in the vehicle is off (excepting the clock) when the door(s) is/are open. So, I surmise that the valve is getting stuck in the "on"/powered position and thus, is running the battery down as I explained above. Thanks for your help with this. I appreciate it. |
#11
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You can always try the junk yard and grab a spare used one. Much cheaper too!
The w124 w201 chassis has a lot of these in the engine bay. w123 more on the 85 models, and in the cabin for climate control (behind CCU). w123 turbo near the brake booster. w201 later model (90+) near firewall and driver fender.
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http://farm8.staticflickr.com/7271/7...144c3fc1dc.jpg |
#12
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Before you replace it see how much power it is drawing. I've rarely, perhaps never, heard of the coil on one of those failing as a short.
-Jason
__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket Tesla Model 3. 205,000 miles. Been to 48 states! Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels. 2014 Cadillac ELR 2013 Fiat 500E. |
#13
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Quote:
Took every fuse out of the box except for #2 and overnight (about 10-11 hrs.), I got a battery drain of 1.2 volts. Incidentally, the battery is an 18 (or thereabouts) month old Interstate that holds a charge just fine. |
#14
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So instead of measuring voltage drop overnight, remove the fuse and put am amp meter in its place. Note the draw with the key off. Then unplug items on that fuse one at a time. Using that method you can find what is actually dragging the battery down.
-J
__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket Tesla Model 3. 205,000 miles. Been to 48 states! Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels. 2014 Cadillac ELR 2013 Fiat 500E. |
#15
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Did this. About 5.34 amps. Disconnected switchover and dropped to about 4.90. This is the circuit with the clock, antenna, radio and trunk light on it. Only disconnecting the switchover dropped the amps.
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