Door Lock Timer Diagnosis and Repair
By Robert Bowen, edited by Wes Stinson
you have a 1990 to 1994 or so Nissan product (Nissan or
Infiniti), and your power door locks are acting strangely, the
problem is most likely caused by the door lock timer. The most
common symptoms of a flaky door lock timer are one or more of
donít lock with the switch or driverís lock knob
locking and unlocking is intermittent
lock as soon as you unlock them
lock when you turn the ignition on, or at other weird times
door lock timer is NOT the problem if only one door doesnít
lock, or locks at the wrong time. The door lock timer only sends
out one unlock pulse to all the doors except for some later cars
that have driverís door priority, where the driverís door
the doors wonít lock with the key in the ignition, that
isnít a problem, itís a feature of 90s Nissan door locks.
Also, if the driverís door lock knob works, but the lock
switch doesnít, it might be the lock switch rather than the
timer (although the timer is more likely to fail than the
car has the door lock timer in a different place:
Q45 - under the center console
J30 - under the driverís side dash
Pathfinder Ė in left rear trunk area
Maxima Ė under driverís side dash
you have any others, let me know.
door lock timer is readily available from any Nissan or Infiniti
dealer for between $65 and $80. The easiest way to repair the
problem is to order a new timer and install it.
youíre handy with a soldering iron, or you want to learn,
there is a cheaper way. The electronics and relay contacts
inside the timers are good for many years. The problem is some
of the soldered contacts between the circuit board and relay.
This happens because when the timers were made, they were
soldered by machine. Some of the parts have terminals that are
larger, and donít heat up as well. This leads to poor solder
connections that should have been caught in quality control, but
were not. Ten or 15 years down the line, these poor solder
connections vibrate loose and corrode, which leads to
intermittently bad connections and all of the symptoms listed
repair the timer you need a soldering iron, some electronic
solder (rosin core), soldering flux and a ďsolder suckerĒ or
youíve never used solder braid to desolder before, practice on
a scrap circuit board until you understand how to use it to
remove solder. Hereís a link to desoldering technique:
youíre a little unclear of solder technique, it wouldnít
hurt to read the following:
tools and supplies to repair the timer will actually cost about
half of what it would cost to buy a new timer, and youíll both
keep the tools and learn a new skill.
the timer out of wherever it is hiding in your particular car.
In this picture you can see where it is in the early Q45.
Donít drop anything on the airbag control module. Unplug it
and remove it from its bracket.
the case off of the circuit board. There are small tabs on the
end with the female plug that are easy to bend out of the way.
you have it apart, you can see the components on the top of the
board. The black box is a relay, and it has the heavy terminals
that usually fail.
for bad solder connections.
the board over and check all of the solder connections,
especially those for the relay.
out this closeup of what a bad connection looks like.
the bad connections.
the solder from the bad solder connection. If youíre
ambitious, re-do all of the relay connections.
cleaned connection should look like this.
Resolder the connections
the flux to the terminal and PCB pad. Then resolder the part to
the board. Look carefully for signs of a cold solder joint,
since you donít want to do this again.
should look like this when youíre done. (or better- mine has
too much solder to be perfect).
Reinstall the PCB and timer module
the timer back where it came from and enjoy your newly working
This web site is the intellectual property of Jesda Gulati and Wes Stinson.