Keyless entry will lock but not unlock. Driving me nuts! Anyone else?

[CoconutPete]

I bought a cheap chinese keyless entry module since I had the glove compartment out while undoing a hackjob stereo install.

I wired it up with gator clips for a proof of concept. It worked. Lock button works, unlock button works.
Wire it in place. Now it will lock but not unlock.

Here is the weird thing: If I manually jump 12V to the unlock wire on the harness in the car (Blue/Red/Yellow), the doors unlock, so there are no busted fuses or problems on the car side (at least one would think).

At this point you're probably thinking "your cheap chinese module is bad" right? Me too!

So ... I slapped a multimeter on the module and the corresponding unlock wire pumps out 12V when I click the unlock button. The same 12V it puts out to the lock wire when i hit that button.

But .... put it into action and it doesn't work!
Is there something funny about the unlock signal that is different than the lock signal?
I'm scratching my head on this one.

[zellamay]

I've installed 3 of these el-cheapo units, with no troubles. I can't imagine a difference in signals. Very rarely, when the car is locked, the unlock does not work until I hit "lock" first. Could it be just chance that you got one method to work and not the other? Of course, I can't see what you are doing, so take this comment for what it's worth: So you have a contact point that unlocks when you apply 12v, and a contact point that does not unlock when you apply 12v. There is a problem in between those points. (bad crimp, broken wire, ???)

[Muzz258]

I don't know anything about the remote locking unit that you are using. The only thing I can think of to add is about the polarity of the unlock signal. Does it need a switched positive or switched negative signal? Look for that pesky negative sign on your electronic multi meter when testing to ensure the polarity is correct.

[CoconutPete]

Well... I can't crimp anymore I guess.

I usually use the little white connectors where you twist the wires together first and then crimp them in there, but I ran out, so I used some solder filled connectors shaped like a tiny pipe (one wire feeds in from either direction) and apparently even though it felt solid and I could not yank either wire out by hand ... somehow the connection was no good. I chopped it and hooked alligator clips to both ends and ... voila!

Mystery solved!

On a side note, those cheapo modules work great and slot right into where (i assume) the OEM would have gone.

Now about those broken tabs on the glove box ...

[zellamay]

Not just you. I've made so many bad crimps that, if I have a problem, that's the first place I look. Glad it was so easy to solve. WARNING: the cheap unit does NOT double lock (I hope that's the right term), which means that if someone can access the inside door handle, they can unlock the door. I've only compared the cheap unit to using the key, and this is true. I read that a factory unit does double lock, but I don't have one to confirm.

[CoconutPete]

Zellamay: Yep, I did notice that it does not "double lock" and I am OK with this. Nothing of value will be kept in this car and if it comes down to getting in easy vs. cutting a hole in the convertible top or something more extreme, I'd almost rather have the perp rummage through my emptry glove compartment.

It's primarily for my own convenience so I don't scratch the door w/ the key if I "miss" when I go to unlock it.

[me77]

You can make an aftermarket system do double-lock: http://www.understeer.com/doublelock.shtml

[zellamay]

You can make an aftermarket system do double-lock: http://www.understeer.com/doublelock.shtml

Now that is cool! Looks easy, so I'll get the diodes and do it next time I have the glovebox out. thanks...