[W126 Coupe] Vacuum Tube Coding

[Gary]

i would like to see those pictures.  



________________________________
From: Yousef <usef4188 at gmail.com>
To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
Sent: Thursday, October 13, 2011 1:09 PM
Subject: Re: [W126 Coupe] Vacuum Tube Coding

Hey Dan

If you want pictures of the vacuum lines for the interior i can take a few .. My dash and most of the interior is out..

Hope that helps

Yousef

Sent from my iPhone

On Oct 13, 2011, at 9:13 PM, Dick Spellman <dick.spellman at gmail.com> wrote:


> Hi Dan,

> 

> I do not know of the color coding for the tubes but, have had to troubleshoot and replace a few of the vacuum circuits in the past.  Basically you have the 3 or 4 vacuum take-off points on the motor.

> 

> Something like,

> 1.  The large brake booster line.

> 2.  The line to the emssions controls like egr, purge canister and air pump if any apply on the euro in your country

> 3.  The smaller line to the firewall valve and one-way valve and splitter

> 4.  The line to the vacuum modulator on the transmission.

> 

> It's the line at the firewall (#3 above) that you are concerned with.  This should feed the vacuum resevoir in the fender and from there you have distribution to the various systems under the dash   Like the hvac distribution switching valve, the euro elevation lighting control in the dash and the seat locking solenoid.  You need to pull the IC and knee bolster to determine which color line is entering the cabin behind the IC and from there you will see their individual routing to the systems/devices.  You should be able to locate the seat solenoid valve which will have electrical and vacuum connections down in and near the steering column.  As I recall it gets hot so it is on the column clear of any material other than steel..  Again, it is controlled by either door pin switch which when door is closed, engine on; activates the valve so the vacuum to seat-back lock is positive.   When any door is opened or you depress the bleeder valve on the

 side of the seat,  the seat ba
ck locks are automatically released.

> 

> I'd guess you need to check the state change on the appropriate door pin switches to be sure the solenoid is being activated electrically then move on to a probable vacuum leak from the firewall to the solenoid or solenoid vac line to the seats.  Perhaps start with a check for voltage at the solenoid connector with engine on, doors closed, if voltage present, the solenoid is working. (as in open-allowing vacuum from engine to flow past the solenoid plunger and to the seat back locks.)  Then check the vac line-in  to the solenoid for the presence of vac with engine on, if none, replace the line through the dash to the firewall valve and.or check the one-way valve at the firewall for damage.  If vac is present, solenoid is working (open) then vacuum should be pulling at the seat junction under each seat and seat locks should be active.  If not, then replace the outbound solenoid vac line to the seat junctions which runs in the under carpet plastic

 raceway along the floor by t
he door sills and comes up from the carpet under each seat.  Last, each pin switch can be checked with an ohm meter once isolated from the electrical ground circuit wiring.

> 

> Good luck,

> 

> Dick

> 

> On 10/12/2011 11:52 PM, L&D gardner wrote:

>> Hi Folks

>> 

>> Does anyone know of a circuit diagram for the colour coded vacuum tubes,I am measuring 60kpa from the ivory tube from behind the engine to the bulkhead junction ,and the seats will lock @ 15kpa with a Mityvac at the same location on the bulkhead but the seats will still not lock as I seem to be getting losses from the dark red and yellow striped tube.Thanks

>> 

>> 

>>                                                                                                                                Kind Regards Dan Gardner 1986 560 SEC (Euro 220kw)

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>> Postings remain property of MB Coupes, L.L.C.

> 

> 

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