Door Microswitches

[Richard Hamilton]

If the passenger door will not lock at all, then I suspect the lock motor has failed. 

 

The other possibility is that there is a bad earth on the lock assembly.  Does the Durametric show Input Signals on the alarm module?  If you can read if the switches are open or closed then this would indicate the earth is OK.  If you can't read the state of any of the switches, the earth is probably the problem.

 

[hankster66]

10 hours ago, Richard Hamilton said:

If the passenger door will not lock at all, then I suspect the lock motor has failed. 

 

The other possibility is that there is a bad earth on the lock assembly.  Does the Durametric show Input Signals on the alarm module?  If you can read if the switches are open or closed then this would indicate the earth is OK.  If you can't read the state of any of the switches, the earth is probably the problem.

 

It doesn't show signals, but does provide actuations to test systems...

- First correction to previous is that the right door does attempt to lock... I could only feel/hear it from outside the car; unlike the passenger side where it is obvious from inside the car, it's not obvious on the passenger from inside the car.

- After clearing codes, and actuating door locks w/ durametric, does the same thing as before, but instead of giving me "60" fault code, it gives me two others:

- 58: "Tank servo motor not energized despite relay activation"; this fault showed repeatedly after each actuation.

- 47: "Control locking synchronization"; I realized that when I did the first actuation, I still had the driver door open; This showed up "red" when open and then "yellow" when closed.

[hankster66]

...one additional observation regarding door locking sounds from outside the car... 

- On the driver side, I can hear and feel the mechanism trying to lock at the door handle area;

- On the passenger side, unlike the driver side there are no sounds/vibrations coming from the door; instead I hear and feel switching immediately before the gas cap area.

 

Again, totally new to P-cars and their workings, so just sharing in case this gives additional clues.

[Richard Hamilton]

I think that it is still pointing towards a bad door lock motor, or a bad earth.  Maybe see if you can find someone local with a PST2 or PIWIS tester who can give it a more in depth diagnosis.

[hankster66]

13 hours ago, Richard Hamilton said:

I think that it is still pointing towards a bad door lock motor, or a bad earth.  Maybe see if you can find someone local with a PST2 or PIWIS tester who can give it a more in depth diagnosis.

Thanks. I forgot to ask before, but when you say "bad earth"... is that a bad ground in the UK? Learn something every day.

[Loren]

14 minutes ago, hankster66 said:

Thanks. I forgot to ask before, but when you say "bad earth"... is that a bad ground in the UK? Learn something every day.

 

Yes, Earth = Ground

[Richard Hamilton]

The door lock microswitches ground (earth) the inputs to the alarm control unit.  On the diagram you can see the brown ground wire which connects to all the switches, so if the ground is bad, none of the switches will signal the alarm control unit.  The brown wire goes through the door plug, to a chassis ground point.

 

The diagram also shows the same ground goes to the power windows and heating, so if they are working you can probably rule out a bad ground.

 

Edited January 19, 2022 by Richard Hamilton

[hankster66]

17 hours ago, Richard Hamilton said:

The door lock microswitches ground (earth) the inputs to the alarm control unit.  On the diagram you can see the brown ground wire which connects to all the switches, so if the ground is bad, none of the switches will signal the alarm control unit.  The brown wire goes through the door plug, to a chassis ground point.

 

The diagram also shows the same ground goes to the power windows and heating, so if they are working you can probably rule out a bad ground.

 

Thanks for taking the extra effort to educate! I ordered a circuit tester as I needed anyone anyway for general troubleshooting, but my hypothesis was that if windows and other things working on that side, likely not a ground fault. I'll test it anyway, but likely to proceed with replacing the locking unit, but waiting to open up the door panel and check things out before ordering anything. I saw some videos/threads that show how to tear down to fix the specific faulty mechanism/switch, but not sure I want to bother with that. The one option I'm considering to OE replacement is using the lower priced and quasi-equivalent vw door lock unit which appears to only requires a minor physical alteration... but again, want to see what's behind the door panel first. Again, thanks for all the info.

[hankster66]

On 1/19/2022 at 12:45 AM, Richard Hamilton said:

The door lock microswitches ground (earth) the inputs to the alarm control unit.  On the diagram you can see the brown ground wire which connects to all the switches, so if the ground is bad, none of the switches will signal the alarm control unit.  The brown wire goes through the door plug, to a chassis ground point.

 

The diagram also shows the same ground goes to the power windows and heating, so if they are working you can probably rule out a bad ground.

 

 

So I completed the project and will detail below, but quick recap here...

• Tested for ground fault (bad earth)... no issue which I suspected as window, door light, etc. were operating on passenger door.
• Taking Richard's diagram, I mapped out my own diagram to troubleshoot connector to locking unit was good... checked out ok.
• Because power was going to the unit and it would not lock/open when triggered, I new I either had a mechanical or sensor problem inside locking unit.
• I tried to see if there was anything obvious (mechanical) I could fix by taking it apart and reassembling, but nothing worked.
• Ordered alternative replacement (part) which I'll explain various options and why I decided on this approach.
• Job completed and for the first time since I purchased the car... no double-beeps and car locks/opens as it should.

TROUBLESHOOTING ELECTRICAL

• As I'm not an electrician (accustomed to reading diagrams), I mapped out my own diagram in the form of the 9-pin connector so I could see what was happening with each wire to make sure something there wasn't a troubling contact or shorted wire to eliminate those before assuming it was the locking mechanism.

 

• Since this was my first project (of several to come) I researched and purchased an automotive circuit tester to test for ground (earth) and to check each of the connections on the connector. With car off, no key ignition and car door open: Connections #1,2,8,9 showed ground connection; and #4 had 12.8 v, while all others no signal. When triggering key fob, #5 and #7 would momentarily show voltage. I didn't go through the various permutations of door locked and ignition key, etc. to fully validate; with power and ground and no response from locking unit I felt that I had enough to point to the unit being the issue.
• I am sure there's probably a better / more methodical way to do this, but I primarily wanted to build some basic troubleshooting skills and have a better understanding of how the electronics work. There are scenarios that could involve circuit breaker and other trouble sources, but there were no indicators for me to research further.

 

 

OPENING UP THE DOOR PANEL

• Having never opened up a door panel, I went on the search on youtube and found an excellent and highly details teardown video which I reference.
• I didn't run into any issues on teardown or reassembly... fairly straightforward.

 

TROUBLESHOOTING LOCKING UNIT - MECHANICAL

• After gaining access to door components and eliminating source power/ground to locking unit, I researched next tier potential fixes. There were a couple of posts/videos out there on identifying and replacing specific sensors. I felt I had more of a mechanical issue going on, or could be dealing with both a mechanical and sensor issue, the latter of which I felt was beyond my capability and time investment interest.
• If you wish to pursue replacing/fixing sensor, I found this "Door locking mechanism rebuild" rennlist thread in the 996 Forum.
• Again, to advance my understanding of what I was dealing with I discovered the video below "Porsche 996 unlock door doesn't open" showing how a particular internal component can get stuck... solution was to shave down (using dremel tool) some of the material and apply lithium. When tearing my unit apart, I actually did discover I had a similar scenario. below the video is an after pic of my unit after shaving some of the material and applying lithium grease. While this appeared to solve this particular aspect, it did not ultimately solve for the lock not operating (pointing to some other mechanical issue and/or faulty sensor).

• The picture below is of my unit and attempted fix. In addition to greasing these related components, I did the same with other moving parts that appeared to be "sticky".

• While not ultimately successful in getting the lock to work, It was nice to check out the inner workings and other potential paths I could have taken. The video below is a helpful and more detailed guide of splitting and reassembling the unit.

 

MODIFYING ALTERNATE REPLACEMENT

• After confirming bad locking mechanism, likely due to bad sensor, I proceeded to research replacement options. Below I list the pricing primarily from Pelican Parts so there may be different pricing available elsewhere, but just showing relative price options here for reference (specifically to right door):
  • Genuine Porsche Replacement: $408 Pelican Parts Genuine Porsche (#9A783701503)
  • 996 3rd Party Replacement: $150 Pelican Parts URO 996 compatible part (#8N1-837-015C)
  • VW Alternative Part: $55 Ebay VW "alternative" part (#1TD837016A)
• There are number of threads advocating for Genuine Porsche replacement, which I totally respect, to a variety of other replacements. For roughly $55, I thought it was worth the gamble to "hack" a solution for a non-critical part. Obviously locking your car is critical and I certainly would not risk purchasing a component that could do more harm; I did not see any harm in a component designed for other german vehicles, other than the risk of winding back at square one... that was ok for my situation where I'm on a journey to tinker and develop knowledge with my "project car".
• The video below walks you through cutting the "excess plastic" (red colored part) from the VW alternative part. Another option to cutting the red, is removing it and replacing it with the piece from the original. I considered that, which requires adeptly putting back in place two sets of springs. To avoid the headache and frustrations I imagined, I decided to cut the excess plastic. If you're skilled at this kind of work and you want to preserve the option of returning the part, you might go a different route.
• I found this video imbedded in a step by step picture guide here.

• Below is a picture of my replacement unit after I trimmed the red part so as not to have any of it extend (to the right) beyond the edge of the unit. The video recommended use of a dremel tool, which I had but I did not have cutting wheel attachment. I used a combination of a utility knife to score the section I was going to cut away, and finished it with a wire cutter. I did not want to bend the plastic for fear of breaking off more than I wanted, so took it in small steps. The plastic is relative soft and not brittle, so you should not have any issues with whatever tool you have readily available.
• The only other adjustment required is transferring the (white) cable assembly from old to new unit.

 

 

IN CLOSING

• 4 months into P-car ownership AND first time car tinkering, it was a pleasure to finally close out my first project. I've been working and prepping for what began as a clutch/flywheel/imsb to discovering I have to fix cam deviation, so now having to drop engine as well... much, much bigger than a door lock... but nice to have a "win" under my belt.
• Since new to P-car, also new to forums, which can have you second guessing everything you do... lots of noise (people with opinions), but often little objective insights (valuable information without judgment). I appreciate having discovered people like Richard Hamilton from across the pond who have in-depth knowledge, long history of helpful posts, and went out of his way to take time to respond to my newbie questions!!!
• I did this post to document my journey in trying to figure out how best to tackle the problem and learn along the way so that the next person could possible spend less time researching and not fall into analysis paralysis in figuring it out. My scenario is I can take my time (not a daily driver), which may not be yours, but now you have options and can choose what works best for you.
• Lastly, I am absolutely certain there are some things I missed and could have done, but here too I pointed them out for the next person to explore. Any other approaches I could have taken not listed above... by all means share!

 

[Richard Hamilton]

Nice write-up.  Thanks for sharing.