Here is a little write up of my latest engi-nerd episode.  Well my 2004 Nissan Murano car remote decided to stop working a few months ago.  It was in my soccer back while it was raining (the same day of the LA marathon) and it seems to have gotten wet.  Well I broke down and bought a new one from the dealer.  I should have done my homework and bought one online as you can find them 60% than the Nissan deal.  What a scam!  So now that I have a good remote I’m determined to fix my old one.  I figure I’m an EE, I should be able to fix this.

So first thing get my BK Precision 2707A digital multimeter (DMM) and some things out of the garage.  I come inside sit down to get going and the DMM won’t turn on.  Ah, dead battery right?  To change the battery you have to unscrew the back off.  So I get a screw driver and replace the battery…nothing.   I take it out and put it back in make sure that there is a good connection and again nothing.  Next, I put it on the Connective Mode where is gives off an annoying sound if the two leads touch.  Schreeze!!!! Well that’s interesting it appears to be on, but the screen doesn’t work.   I love how all projects have scope creep.  Well I fidget around with this and do some online searching to see if there are any similar issues. No luck.   I found out that the version of my DMM has been discontinued and the company will give me a $30 discount on a new one if I turn mine in.  I figure I might as well tear into this to see if I can figure out what is wrong before I bite the bullet and guy a new one.  It unscrews pretty easily and is a pretty simple board.   The interesting thing is the screen isn’t soldered onto the board.  It has this funny silicon-metallic stand that the screen fits on.  A plastic cover snaps on to the PWB and holds the screen and stand in place.  After sliding this stand around I can see the screen display characters which means the problem is likely the stand to PWB connection was just off (I may have dropped the DMM a while back).  So I snapped the screen cover on and using a small screw driver adjusted the silicon stand in place.  Wa La! the screen works.

Now back to the real project.  I did a quick check to ensure the battery is connected to PWB and nothing.  Interestingly, the buttons don’t pass a connectivity check when I put the probes directly on it.  So I then placed the PWB into the good remote to make sure that it wasn’t the little buttons.  nothing.  (not really sure how the little buttons work at this point, but I’ll try to stay focused).  Now that the first couple of easy ideas have failed I think I’m onto more work.  I’m going to take a picture of the PWB and mark all the connections and then check to see if it matches the good remote.   I’ll report back with an update after that is done.

Final Update:

Well I went through probing the PWB and drawing out all the connection points. Which actually didn’t take too long.

After going through it I realized that the Vcc (power) didn’t connect to the switches any longer.  The two red circles should be connected, but they weren’t.  The little holes are there to connect the traces on this side of the PWB to the other side.    For some reason the connection from one side to the other wasn’t working.  So that is an easy fix.  I turned on my soldering iron and place two wires through the holes then soldered each side to the PWB.  My soldering job is actually a pretty horrible job and think the tip on my soldering iron may need to be replaced.  I think I’ll save that project for another time.

After I soldered in each wire I checked the connectivity again and it all seemed to check out.  I then went out to my car and reprogrammed the car following these directions (found on this forum):

1. Close and lock all doors with the driver’s side power lock/unlock switch.

2. Insert key into ignition and remove it from the ignition key cylinder at least six times (or more) within 10 seconds. Your Hazard Lamps will flash if you have performed this step successfully.

NOTE: Withdraw the key completely from ignition cylinder each time. If this procedure is performed too fast, system will not enter programming mode.

3. Insert key into the ignition cylinder and turn to the ACC position.

4. Within 5 seconds, push ANY button on the remote transmitter. Your Hazard Lamps should flash.

NOTE: Do not press the button more than one time in this step. If the button is pressed more than one time, the programming procedure will not be successful.

5. If there are any remaining transmitters (including existing ones), unlock then lock all doors using the driver’s side power lock/unlock switch and within 5 seconds, push ANY button on the next remote.

Your Hazard Lamps should flash.

Repeat this step for each transmitter (including all existing transmitters).

6. Turn the key to the OFF position, remove keys from the ignition, unlock doors using the driver’s side power lock/unlock switch and open the driver side door.

At Step #4, the lights flashed and right away I knew I had fixed my remote!  I didn’t have my new remote with me so I went and got that one, followed the programming instructions again, and then confirmed both are working.  I think I’ll use the new car remote for now and keep the one I fixed as a back up since I don’t feel too confident about my soldering job.

Project Complete!