Deep into the weeds with the Door Lock Module (original)

[burch]

Hey everyone -

Decided to finally take care of my doors and locks that sometimes worked correctly. Started by taking out the latches, cleaning them, and performing a "wedgectomy" on all 4. Did a lock and latch procedure on both sides, and the doors have honestly never latched better or easier than they do now.

I previously modified the DLM to have the inline 10Amp safety fuse on the large power wire. Even with the old locks at about 80% efficiency, the DLM worked for a while, but would blow the 10A fuse every now and then. To improve the reliability of the system, I performed the "Elvis DLM mod" (http://www.teslorean.com/assets/uploads/documents/pdf/Door-Lock-Module-mod.pdf, if you're unfamiliar), using components equivalent to what Elvis has called out in the document. I also purchased new relays for the DLM and installed those as well. I have also examined my door lock solenoids, which are in great shape, move freely, and are unburned inside.

Wouldn't be posting this if everything worked correctly :)

With the doors open, and the latches locked, I attempted an unlock from the passenger side internal button. Both doors unlocked. I heard the relays click and the 10A fuse blew. Changed the fuse, tried again from the driver side. Same result.

Even with the fuse blown, I was able to determine the following:

1. The relays are assuming the right states when lock/unlock are pressed. They are staying in those states after the press, and not pulsing (I believe this is the correct behavior)
2. If I disconnect one door's electrical connection to the lock bellcrank, just to test the other door, I still blow the fuse. Doesn't seem to be one door or the other.
3. My inline fuse holder is one with an LED indicator. Interestingly, the indicator stays on (with the blown fuse) nearly all the time.

I've checked the resistance of all the resistors, the capacitors and the diodes/rectifiers (as much as possible on the board). There are no bad solder joints, and I'm not getting any resistance across the solder connections.

Any ideas on what I can check/test next? Obviously a Digital DLM would correct the issue as well, but it seems I'm not all that far off with what I have. Thanks!

[Bitsyncmaster]

Your unit may have a longer timing than most and if so that could blow a 10 amp fuse. I seem to recall each solenoid draws 10 amps but since the time on is so short that 20 amps does not blow the fuse. I would try a fuse without the LED but a 15 amp. fuse should still protect if the relays stick. The problem with the OEM and lockzilla units is they use a large capacitor to create the timing on the relays and that makes them open slowly and burns the contacts.

[burch]

Your unit may have a longer timing than most and if so that could blow a 10 amp fuse. I seem to recall each solenoid draws 10 amps but since the time on is so short that 20 amps does not blow the fuse. I would try a fuse without the LED but a 15 amp. fuse should still protect if the relays stick. The problem with the OEM and lockzilla units is they use a large capacitor to create the timing on the relays and that makes them open slowly and burns the contacts.

That may be the issue. I did try a 15 amp fuse and ran into the same problem. How high should I go?

[burch]

After more testing:

15A fuse - successfully unlocked doors, blew
20A fuse - successfully locked doors, blew
25A fuse - successfully unlocked doors, stayed intact, but appeared to hold solenoids in one place. Could not lock doors until power was disconnected.

[Bitsyncmaster]

I think the OEM controller times the solenoids for about 1 second of on time. The LockZilla was much shorter (about 0.1 seconds). Can you time how long the relays stay engaged. If you replaced the relays with higher resistance coils your timing will increase. The LockZilla used much lower resistance relays which is why the timing is so short.

[burch]

Thanks, Dave! I'm going to pull the module and just do some quick bench tests to look at the relays. I don't know for sure that they are disengaging.

[DMC-81]

Oh boy. I have been down this road before. :)

Here's my thread on the topic: http://dmctalk.org/showthread.php?13059-Assessing-OEM-Door-Lock-Module-(DLM)-and-solenoids

Long story short.. In my case, my solenoids were the problem and needed to be rewound. After rewinding, I didn't blow any fuses.

In the thread, there is information on part numbers for new relays if you find that you need to replace them.

[David T]

If you are blowing that in-line fuse one or both (more likely both) solenoids are burnt. Rewind them. The relays and the DLM do not suck up anywhere near enough current to blow the fuse. Only burnt solenoids will do that. Disconnect the solenoids and the DLM should work just fine and the fuse won't blow.

[burch]

Ok, taking a little advice from everyone on this thread. First of all, I'm just starting with the passenger side now. I've disconnected the bellcrank power on the driver side for the time being.

I've also now rewound the passenger side solenoid. Tedious, but at least I know that it is fresh and when it was done.

Plugging everything back in, I was running into the same issue. What I'm finding is that the new relays are actually sticking in their positions as opposed to "pulsing" for a fraction of a second. When the opposite command is sent to the unit, both relays are stuck and the fuse blows.

Am I missing something here?

[burch]

Clarification from above: I'm manually testing the relays, and they are sticking in their position.

[DMC-81]

Clarification from above: I'm manually testing the relays, and they are sticking in their position.

Yes, in my research, sticking relays were also a common problem. It's good to ensure that your solenoids are not shorting, but many times the relays need to be changed. That's why I mentioned the part numbers. I rewound the solenoids as they were my root cause, and although my relays weren't sticking, I replaced them anyway.

I disagree with David T in that the ONLY cause of the fuse blowing is a burned solenoids. A short anywhere (for example, a short in the harness at the top of the door) can also cause it.

You can check with Toby at DMCNW to see if he has any in stock.

[burch]

These are brand new ones from Toby, I'll contact and see how he wants me to test. Thanks!

[David T]

Once you burn up the contact points on the relays they will tend to "stick" or not open quickly anymore because of the arc. The relays burn up because of the excessive load caused by the shorted solenoids. You can dress the contact points on the relays but that is a very short term fix. The better fix is to replace the relays and rewind the solenoids. Disconnect the solenoids and see if you still blow the fuse. If youl do it is possible you have a shorted wire going to the solenoids but more likely you just have burnt solenoids.

[Elvis]

Use the relays I suggested and they will work fine.

the original BOSCH units tend to stick. Don't know how others work.

But still - rewind the solenoids, they can not be measured by resistance, only by inductivity.
10 A fuse burns - solenoid bad.


Side note - I am testing at work a circuit that draws up to 100A for a short moment.
small cheap relays will stick after a few switches. The one I use to replace the BOSCH relay
in the ECU now switched around 10000 times and still works fine.
Sombody back then said you need an insulated relay filled with gas...well the ones that stuck
after a few cycles were insulated ones - so I stay with the ones that I've been using for more
than 10 years.


Thanks for reading my old how to - that I never replaced with the updated one with the 10A fuse
and the remote instructions.