02 E320 W210 rear door locks wont unlock
 

My rear doors lock but will not unlock. I looked under the seat at the PSE and see six yellow lines and one white. I was hoping to find a way to use a mityvac and identify the six but it appears they are permanently attached to the PSE pump.

What are the odds both rear door acuators are bad? It seems strange to me that they will lock but not unlock.

Can anyone explain the W210 rear door lock system? I hate to have to remove the panel.

I don't think the lines are permanently attached, they have plastic fittings with an o-ring type deal. I think if you pull on them they will pop off the pump.

OK, I'll check... Thanks.

I was hoping to find a rubber hose as in the older W126s. The W210 is all new to me.

I think they went to the fittings style connection on the later W124's and W201's....my 190 has the fittings and my W124 did too....W126 is rubber.

I suspect something in the PSE. It seems odd to me the door pods would lock but not unlock. If the diaphragm in the pods leaked or a leak in the line to the pod, I would think it would fail to lock. Besides, I'm looking for an excuse not to pull the door panel until it needs window regulator. Which might be soon from what I read about the W210s.

If there's a leak, you should hear a hiss for a few seconds somewhere after actuating.

Have you tried resetting the CAN bus by disconnecting the battery for a minute? If the problem goes away for a while, you'll know the vacuum side is OK, and one of the modules on the bus is causing the problem.

I have seen them fail where they will lock but not unlock. If they get a tear in them sometimes the suction from locking will close the split and they will still lock, but the pressure to unlock will blow past a split in the rubber/silicon. If its both at the same time then that is strange though....

Tis the week for lock gremlins...

My '84 SD had me locked out of the trunk this week. It seemed to be related to the warmer weather. I tried it early when it was cooler out, it unlocked.

A closer look revealed the '84 300SD has an electric servo motor in addition to the vacuum actuator for the trunk lock. The servo is driven by the factory alarm system to lock the trunk and had become stuck in the locked position. Simple fix... unplugged it. Trunk still locks/unlocks with the vacuum system.

Such a simple, reliable automobile. 30 years old and everything works perfect... except for the alarm.

I cannot hear any hissing from leaks. But, there's a lot of things I can't hear my wife say also. ;)

I'll pull those lines from the PSE and use the MityVac to ID which pod the go to. Then I can check the rear door pods, lines from that point.

That makes sense how a vacuum pulls a crack closed after thinking about the shape of the diaphragm.

In thinking about it I bet both rear locks are on the same circuit, so if one actuator is venting the pressure during the unlock cycle, both would likely not work.

There are six lines coming off the PSE. I assume one for each door, trunk and gas filler. So, either both rear actuators are bad or its the pump.

I'll sort it out later.

I'm off to get new Michelin tires mounted!

Tire Rack just lightened my account with the purchase of tires for the E320 and SIX tires for my Dodge truck. :eek:

I had another look at this today... still a mystery.

On the PSE three of the lines are common and labeled A,B and C. Using the mity vac I can lock the left and right rear door when pulling a vacuum on lines A and C. Both hold and show no signs of a leak however, line C leaks down and does not lock the trunk or the gas flap.

Hmm... Both the trunk and gas flap lock and unlock as intended when using the key fob.
Stumped.