Inertia switch failure, tripping thermal relay of door lock electrical?

[ritztoys]

My car has worked well for a long time. This weekend after (externally) locking door and unlocking I noticed my thermal relay in door circuit began "tripping" constantly on way home.

Could the inertia switch cause this behavior?

Any help appreciated, I don't know where to test first to find this fault and correct.

[DMCMW Dave]

Yes that is how it is supposed to work. It unlocks the doors in an accident so you can get out of the car.

[ritztoys]

Yes that is how it is supposed to work. It unlocks the doors in an accident so you can get out of the car.

Thanks Dave, The inertia switch is causing the relay "tripping" then? I don't have an extra to test this new behavior from my doors, so just replace the switch?

[DMCMW Dave]

Thanks Dave, The inertia switch is causing the relay "tripping" then? I don't have an extra to test this new behavior from my doors, so just replace the switch?

Unplug the switch and the locks should act normally. But the fuel pump will be disabled (car won't run) unless someone has bypassed it somewhere else.

You can temporarily bypass the inertia switch to ground the fuel pump to drive the car.

[ritztoys]

Unplug the switch and the locks should act normally. But the fuel pump will be disabled (car won't run) unless someone has bypassed it somewhere else.

You can temporarily bypass the inertia switch to ground the fuel pump to drive the car.

Thanks again Dave, I now know what to do. The door lock "brains" are kinda of 'salty' in $$, inertia switch is easier on the wallet! :thankyou:

[ritztoys]

Well........ after removing inertia switch from circuit and testing as suggested, the problem remains?

Could the door lock "brains" internally be causing my lock problem? The thermal relay "trips" as soon as I connect the battery? (with inertia switch removed)

Should I open the door trim and check the electrical inside of the door? Could mechanical parts of door lock cause this problem?

[DMCMW Dave]

You could just disconnect the module. Locks will still work manually. It's likely that you have a bad solenoid or two in the doors, that can cause similar issues.

The inertia switch may not be the issue, more likely are solenoid or the lock module.

Sent from my iPhone using Tapatalk

[Bitsyncmaster]

There was a problem with the OEM door lock controllers with sticking relays but that would normally just over heat the solenoids and then you got locked in the car. When I first got my car, the door locks would intermittently click on and off when driving. That just turned out to be a bad connector pin on my door lock unit. I designed my own door lock controller anyway to prevent the relay sticking problem of the OEM unit.

[ritztoys]

Thanks for your experience in trouble-shooting this issue. As far as I can tell this is an original door lock controller, when I disconnected the multi-pin connector from the wiring harness and then re-connect the multi-pin, I see a spark when doing this(maybe a bad solenoid). Then the thermal relay begins to open & close with that loud 'click' continuously.

So........my trouble-shooting experience tells me (and after reading your post), I have a 'frozen' relay or two in the door lock controller, or maybe a bad solenoid?

[Bitsyncmaster]

Thanks for your experience in trouble-shooting this issue. As far as I can tell this is an original door lock controller, when I disconnected the multi-pin connector from the wiring harness and then re-connect the multi-pin, I see a spark when doing this(maybe a bad solenoid). Then the thermal relay begins to open & close with that loud 'click' continuously.

So........my trouble-shooting experience tells me (and after reading your post), I have a 'frozen' relay or two in the door lock controller, or maybe a bad solenoid?

Yes, sounds like a relay is stuck on.

[David T]

If you are going to use the original door lock module then you should cut a 10 amp in-line fuse into the big red wire. If it blows it will not reset like the breaker and if it blows you know you have a problem. Most likely a stuck relay and usually burnt solenoids too.

[ritztoys]

Yes, sounds like a relay is stuck on.

You hit the answer perfectly! I ventured inside of the door lock controller(outside tie-strap was loose), guess what I found........Stuck relay :yesss:

So I got out my trusty 'point file' and cleaned up the contacts, then I re-assembled everything electrical and hooked up the battery..............no sparks and the doors work correctly now and the thermal relay is quiet, no "clicking sound".

Needless to say I'm one happy m.......r f.......r, problem solved for now. I have a better understanding how this system works now. :woot:

[Bitsyncmaster]

You hit the answer perfectly! I ventured inside of the door lock controller(outside tie-strap was loose), guess what I found........Stuck relay :yesss:

So I got out my trusty 'point file' and cleaned up the contacts, then I re-assembled everything electrical and hooked up the battery..............no sparks and the doors work correctly now and the thermal relay is quiet, no "clicking sound".

Needless to say I'm one happy m.......r f.......r, problem solved for now. I have a better understanding how this system works now. :woot:

It's the circuit design of the controller that causes those relay to burn the contacts. They use a large capacitor to power the relay coils to provide the one second timing. So the voltage on the relay coil drops slowly hence the contacts open slowly and cause burning because they open slowly.

The old Zilla controller used the same circuit but used heavy duty relays to lessen the contact burning.

[PJ Grady Inc.]

It's the circuit design of the controller that causes those relay to burn the contacts. They use a large capacitor to power the relay coils to provide the one second timing. So the voltage on the relay coil drops slowly hence the contacts open slowly and cause burning because they open slowly.

The old Zilla controller used the same circuit but used heavy duty relays to lessen the contact burning.

We have Lockzilla's in stock again. We have never encountered contact burning or sticking with the relays they use. They are bulletproof and can be found on our website along with much more reliable solenoids if needed.
Rob

[David T]

The relay contacts in the OEM door lock module are very underrated for the load they have to control. The problem is the relay contacts have to interrupt an inductive load. To do that creates a large arc and if the contacts are not large enough to spread the arc over a bigger area it causes burning of the contact points. Cleaning and redressing them is a very temporary fix. The coating that was on them to help prolong their life is gone and you most certainly have shorted out the solenoids which will cause an even higher current to surge through the relay contacts. The fix now is to rewind or replace the solenoids and upgrade the OEM door lock module (there are how-to's) or replace it. I would get the LockZilla. But keep in mind, even a Lockzilla isn't going to help if the solenoids are burnt and you don't fix or replace them.

[ritztoys]

The coating that was on them to help prolong their life is gone and you most certainly have shorted out the solenoids which will cause an even higher current to surge through the relay contacts. The fix now is to rewind or replace the solenoids and upgrade the OEM door lock module

Thanks for the advice, I have a Lockzilla on order now. If my thermal relay was 'tripping', it was kinda of protecting my solenoid. (Right?)
Since I made a temporary fix to my contact surfaces, the door locks operate properly now. (So my solenoids my be working correctly)

I'm capable of rewinding, but don't want too if not needed. So..........with the Lockzilla and currently working door solenoids I should be Ok?

[David T]

Thanks for the advice, I have a Lockzilla on order now. If my thermal relay was 'tripping', it was kinda of protecting my solenoid. (Right?)
Since I made a temporary fix to my contact surfaces, the door locks operate properly now. (So my solenoids my be working correctly)

I'm capable of rewinding, but don't want too if not needed. So..........with the Lockzilla and currently working door solenoids I should be Ok?

If the relay contacts welded themselves together you have to figure you burnt the solenoids (both of them). Even a Lockzilla will not work correctly with burnt solenoids.

[ritztoys]

If the relay contacts welded themselves together you have to figure you burnt the solenoids (both of them).

Even though they 'seem' to operate correctly now? Also it was only the passenger door that was affected.

Can I check the resistance of these coils before removing & rewinding?

So.......does someone have access to your door solenoids and can measure these values of an nu-burnt solenoid? (Measure this at White connector, after it is separated from wiring harness. Since mine may be 'burnt'?)

[Bitsyncmaster]

Even though they 'seem' to operate correctly now? Also it was only the passenger door that was affected.

Can I check the resistance of these coils before removing & rewinding?

So.......does someone have access to your door solenoids and can measure these values of an nu-burnt solenoid? (Measure this at White connector, after it is separated from wiring harness. Since mine may be 'burnt'?)

If your solenoids are still working, you probably did not do much damage to the solenoids.

[David T]

You cannot test them properly with an ohmmeter, you would have to use an inductance meter. Guaranteed you burnt them, you will see when you unwind the coils.

[Bitsyncmaster]

You cannot test them properly with an ohmmeter, you would have to use an inductance meter. Guaranteed you burnt them, you will see when you unwind the coils.

Ohmmeter would be just as good checking as inductance. If some of the windings shorted it would result in less ohms. The same would hold true for reading inductance.

[ritztoys]

Ohmmeter would be just as good checking as inductance. If some of the windings shorted it would result in less ohms. The same would hold true for reading inductance.

What he said! I completely agree with you, I feel better now. :thumbup:

[NckT]

You cannot test them properly with an ohmmeter, you would have to use an inductance meter. Guaranteed you burnt them, you will see when you unwind the coils.

Without going to the n'th degree of applying a sinusoidal frequency to the inductor to quantify the Q value of an inductor ie the solenoid coil, it'll be much easier to measure the resistance of each coil at the disconnected church window electrical plug at the central locking module. From here, it's easy to 'momentarily' (less than 2 seconds) apply 12v from the central locking circuit breaker to each individual solenoid from this point to check that each solenoid operates the door lock/ unlock mechanism.

If the resistance values are within 5% of each other and work as tested above, I'd leave the solenoids in place.

However, if one of the relays in the locking module has stuck on for a long period with the main lead of the vena locking module connected to the circuit breaker, then chances are the solenoid would be suspect of having a partial short.

Good luck with the tests

[DMC-81]

Even though they 'seem' to operate correctly now? Also it was only the passenger door that was affected.

Can I check the resistance of these coils before removing & rewinding?

So.......does someone have access to your door solenoids and can measure these values of an nu-burnt solenoid? (Measure this at White connector, after it is separated from wiring harness. Since mine may be 'burnt'?)

I think there may be some information in this thread where I repaired my stock lock system. Look on page 6 , post 60 for the resistance: http://dmctalk.org/showthread.php?13059-Assessing-OEM-Door-Lock-Module-(DLM)-and-solenoids

[David T]

Ohmmeter would be just as good checking as inductance. If some of the windings shorted it would result in less ohms. The same would hold true for reading inductance.

I am surprised you said this. An ohmmeter isn't sensitive enough and even if you get one that is sensitive, the tolerance is bigger than any difference you would see in ohms. Only by "ringing" the coil can you tell if it has shorted turns. Not necessary if you melted the relay contacts and were tripping the circuit beaker. All of that power going into the coils most certainly burnt them up. Will it still work, maybe but it will have much less power and will consume a LOT more current. Enough to eventually kill the Lockzilla. One way to see how bad it is, put a 10 amp in-line fuse into the big red wire and see if it blows. If the solenoids consume 10 amps they are burnt.

[Bitsyncmaster]

I am surprised you said this. An ohmmeter isn't sensitive enough and even if you get one that is sensitive, the tolerance is bigger than any difference you would see in ohms. Only by "ringing" the coil can you tell if it has shorted turns. Not necessary if you melted the relay contacts and were tripping the circuit beaker. All of that power going into the coils most certainly burnt them up. Will it still work, maybe but it will have much less power and will consume a LOT more current. Enough to eventually kill the Lockzilla. One way to see how bad it is, put a 10 amp in-line fuse into the big red wire and see if it blows. If the solenoids consume 10 amps they are burnt.

Check one with your inductance meter and tell me what the inductance is and what frequency your meter uses. I will see if I get the same results.

[David T]

I would if I could but I don't have an inductance meter. I know a 10 amp fuse won't blow on good solenoids unless you lock and unlock them a bunch of times quickly. An amp-meter won't get a good reading because it is too quick to get an accurate reading. The variation between good coils will be larger than anything you will see on an ohmmeter if you check it against a burnt coil. For the CB to pop you are consuming a lot more than 10 amps and it keeps resetting putting MORE power into the coils getting them hotter and hotter. Eventually you drain the battery. Doesn't take long but til then you can't unlock the doors to get out.