[clarknova]

I purchased my '99 E300TD in the summer. The console switch trunk release worked for about the first week. I don't remember if the trunk release button on the fob worked at all. In any case, after about the first week of owning this car, neither the console trunk release nor the remote trunk release buttons have any effect other than to light the LED to let me know that the button was pressed.

The PSE unit does function. The driver and passenger door locks work fine. In fact, since I was unable to open the trunk by pressing the button on the trunk itself, and I have never succeeded in inserting the key all the way, despite numerous applications of penetrating oil, I connected the pneumatic hose for the trunk release to one of the nozzles on the PSE for the passenger doors. Thus when I press the unlock button to open the passenger doors the trunk opens. And when I open the driver door after a drive. Or the front passenger door. And when I unlock the driver door with the key. But not always, just sometimes. Anyway, the PSE works, just not when the trunk release buttons are operated.

AD80.20-P-3002B tells me that this could mean "PSE variant coding incorrect". I can't imagine why the coding would be incorrect a week after I purchased the car and had done no work on it to that point. To this day I have not touched any of the electronic components in this car.

What to do? I'd like to re-plumb the PSE correctly and have all my door locks working mostly. I'd like to recover proper functioning of the trunk release switches, but I don't know how to proceed from here. Any pointers?

 

[mrboca]

I believe the trunk release line from the PSE is shared with the rear seat headrest release function. From port d, the line is t-junction connected to the headrest and trunk release actuators. If I remember correctly a pressure application will open the trunk and a vacuum application drops the headrests. You can try the headrest operation. Sometimes the headrest actuators leak air, so lifting the headrests and dropping them several times may solve the leakage issue.

If this does not solve the problem, the port d may have a leakage / blockage. If you have an access to MB SDS, you could look for fault codes for the PSE (B series). It may indicate a safety shutoff / over pressure pressure issues for this particular port.

 

[illstplaya]

What happens when you push the trunk lock in? Put the trunk vacuum line back where it's supposed to be. Then make sure all the doors are unlocked and then press the trunk lock in and see if it opens. Pushing the lock in, activates the PSE pump. So this will be the final test before you start looking for leaks.

 

[Darkmann]

Check to be sure the switch itself is not broken - mechanically. Just replaced mine a couple of weeks ago with a unit I purchased from eBay. Follow this thread for that discussion: http://www.benzworld.org/forums/w210-e-class/2916137-broken-trunk-remote-button.html. If it turns out you need to replace just the switch itself, I have one available for free. Initially I purchased the switch only. But after I pulled out everything, turned out that in my case (MY2000), I needed to replace the entire switch/board as a unit. Not cost effective to return the switch back, so I kept it.

 

[SocalSam]

Reviving an old thread...

My new to me 1999 E430 has non-op trunk release switch. Trunk will open with fob and also manually. Previous owner reported interior switch never worked and in fact, the switch itself was broken. He also replaced PSE with an ebay buy and kept the old PSE which I have. I replaced console switch assembly. Trunk release switch will not open with old PSE or replacement PSE. I replaced the console switch assembly a second time with no joy. Both switch assemblies show red LED on with trunk open.

So far:

1. Central locking works nicely with ebay PSE including trunk unlock after about 5 seconds. (I'll try the headrest thing to see if that time improves.)
2. Fob trunk release works. I got it to work by wriggling the trunk harness. There were no breaks or obvious chafing.
3. Parking lights fob door lock and unlock.
4. Looked at owners manual for trunk lock and unlock separately with key instructions. Trunk unlock with key will roll down all windows.

I am hoping this is not a PSE configuration issue. I do not have access to scan tools. Thoughts please.

 

[mrboca]

Hello

Follow item 6.0 in the attached. Basically you are checking the switch operation at the PSE end from the removed connectors.

STAR TekInfo

 

[SocalSam]

Hello

Follow item 6.0 in the attached. Basically you are checking the switch operation at the PSE end from the removed connectors.

STAR TekInfo

Thank you mrboca. Thanks for link to STAR Tekinfo. Please excuse my ignorance, very new to Mercedes. Best I can do for now is check continuity between switch and PSE and the PSE to trunk latch. I'm thinking there is chafing or a break in the trunk area wire harness as there was an issue there before. STAR Tekinfo refers to socket box tester which would be awesome to have to test voltage values. Is that dealer only or are there aftermarket clones?

 

[Witek_M]

Those socket boxes and test cables are no longer available. They were thousands in the past. Cute but not needed.
I find it easier to look at wiring diagram and associated diagnostic sheet. Connector 1, pin 5 Brown/White to connector 2. pin 4 Red/White.

 

[mrboca]

All you need is locate connector 1 pin 5 (brown / white wire) and apply ground with the trunk is closed. You can pierce the wire or back-probe. If the trunk opens, then it is the wiring / switch. All the switch does, is to apply ground when operated (open trunk).

 

[SocalSam]

Gentlemen, thank you! I'll report findings shortly.

 

[SocalSam]

Those socket boxes and test cables are no longer available. They were thousands in the past. Cute but not needed.
I find it easier to look at wiring diagram and associated diagnostic sheet. Connector 1, pin 5 Brown/White to connector 2. pin 4 Red/White.

C2, P4 (rd/wh) connected to switch? Are you saying jump C1, P5 to C2, P4 and test switch?

All you need is locate connector 1 pin 5 (brown / white wire) and apply ground with the trunk is closed. You can pierce the wire or back-probe. If the trunk opens, then it is the wiring / switch. All the switch does, is to apply ground when operated (open trunk).

C1, P5 (br/wh) connected to trunk latch? Applied ground, no trunk open.

 

[mrboca]

C1, P5 (br/wh) connected to trunk latch? Applied ground, no trunk open.

No, it is an input to the PSE (A37). The trunk release switch puts a ground on this pin to signal PSE a request for trunk to open. This is in the diagram that Witek has posted. By applying a ground on this wire, you are effectively bypassing the switch, bringing it close to the PSE.

Make sure that the connector 1 is CONNECTED to the PSE when you apply ground. to this wire.

The actual trunk latch control has not much to do with the trunk release switch, as you already indicated that the trunk is opened by the FOB trunk button.

 

[SocalSam]

No, it is an input to the PSE (A37). The trunk release switch puts a ground on this pin to signal PSE a request for trunk to open. This is in the diagram that Witek has posted. By applying a ground on this wire, you are effectively bypassing the switch, bringing it close to the PSE.

Make sure that the connector 1 is CONNECTED to the PSE when you apply ground. to this wire.

The actual trunk latch control has not much to do with the trunk release switch, as you already indicated that the trunk is opened by the FOB trunk button.

Ooph, applied ground to the connector, will try with PSE tomorrow. There is no way to back probe the connector. Will applying ground to PSE pin 5 work?

 

[mrboca]

As long as connector 1 is plugged in, as it has other signals that the PSE needs.

You can pierce the brown/white wire insulation with a needle (poor man's piercing tool), and apply ground.

OR

You can remove the connector 1, locate pin 5 on the connector, and measure the resistance with respect to ground. It should have high resistance. When you, or someone lifts the trunk release lever switch (to release trunk), the reading should be low resistance ( short circuit), as the other side of the switch is connected to chassis ground.

 

[SocalSam]

As long as connector 1 is plugged in, as it has other signals that the PSE needs.

You can pierce the brown/white wire insulation with a needle (poor man's piercing tool), and apply ground.

OR

You can remove the connector 1, locate pin 5 on the connector, and measure the resistance with respect to ground. It should have high resistance. When you, or someone lifts the trunk release lever switch (to release trunk), the reading should be low resistance ( short circuit), as the other side of the switch is connected to chassis ground.

Understood, will report back with results.

 

[Witek_M]

C2, P4 (rd/wh) connected to switch? Are you saying jump C1, P5 to C2, P4 and test switch?

Absolutely not. That would blow the fuse and put trunk release switch in path of direct short.
You measure voltage between those two pins. This verifies the switch and its connection to ground point W6/1.

 

[SocalSam]

My newness is showing, thank you for your patience.

...You can remove the connector 1, locate pin 5 on the connector, and measure the resistance with respect to ground. It should have high resistance. When you, or someone lifts the trunk release lever switch (to release trunk), the reading should be low resistance ( short circuit), as the other side of the switch is connected to chassis ground.

C1, P5 to ground shows open with no switch pull.
C1, P5 to ground shows open with switch pull.

Absolutely not. That would blow the fuse and put trunk release switch in path of direct short.
You measure voltage between those two pins. This verifies the switch and its connection to ground point W6/1.

C1, P5 to C2, P4 shows no voltage.

 

[Witek_M]

C1, P5 to C2, P4 shows no voltage.

With switch pulled?

 

[SocalSam]

With switch pulled?

Trunk release switch on console. Fob trunk release works.

 

[Witek_M]

Trunk release switch on console. Fob trunk release works.

So it appears that switch is no good. Now is the time to try grounding connector 1, pin 5. Both connectors plugged in.