2000 v70 central locking system inconsistantly function

[fireman51]

My 2000 V70 wagon has an inconsistent functioning central locking system. I have replaced the master control panel, at the driver's door, on three occasions and all seem to function for a while, then go haywire. Tried purchasing modules from Switch Doctor and most recently from Volvo. System works sometimes then some doors lock, some do not. Usually, the driver's door key works the best. Wife says, fob hasn't worked in quite a while, possibly a battery issue. Only the driver's door has a key port. Assistance please!

[Sommerfeldt]

Change your key fob batteries first of all. Also check that all buttons on them are functioning. On my old S70, central locking went mental when one of the fobs had a bad battery and a button that was half stuck.

Then, check that your receiver isn't bad - I'm guessing it behind the glove compartment. Check electricals and the antenna.

Start with the basics.

- S

[Ozark Lee]

The remote receiver on the 70 series is a box on top of the instrument cluster but there isn't much that you can check on it besides making sure it is plugged in without VIDA/DICE.

...Lee

[BEJinFbk]

Let's isolate the problem - Forget the fob and/or receiver for a minute.
Concentrate on the locking systems behavior just using the switches in the doors.
From your description, it sounds like not all of the doors are responding together
as they should. More than likely, it's the individual motors in the latching mechanisms.

Is this problem temperature related? Are the locks failing when it's hot?
If so, you probably have trouble related to the protective device in each
of the lock motors. They can be either repaired or replaced.

[rspi]

[Sommerfeldt]

If the locks are responding better to the key than the remote, then I'd say it's most likely better to NOT get bogged down in individual motors and whatnot.
Start with the basics - change batteries and check connections.

- S

[BEJinFbk]

If the locks are responding better to the key than the remote, then I'd say it's most likely better to NOT get bogged down in individual motors and whatnot.
Start with the basics - change batteries and check connections.

- S

You're missing my point of isolating the primary functions of the
base central locking system before moving on to the external input
from the keyless RF system. The remote is a whole extra layer of stuff
to diagnose that depends on the correct operation of the basic central
locking system. The key to avoiding chasing your tail is to be sure that
the basic hard wired foundation of the system is functional first.

There are three outputs from the central lock control module:
Drivers, tailgate and the other three door lock motors.
The input from doors switches tells the module to energize the
outputs of all three of those segments at once.

If there are locks that are failing to operate fully and simultaneously
when you use the door switches, it's very likely that there's an issue
with those particular motors.

[Sommerfeldt]

And you, BEJinFbk, are missing most of OP's post, where he states that he's already thrown parts at it ("I have replaced the master control panel, at the driver's door, on three occasions") - some of which relates to what you're saying he should check.

Why in all holy's name would you try "isolating the primary functions of the base central locking system before moving on to the external input from the keyless RF system", when this could be exactly the same issue I had on my S70? The main rule in everything with these cars should be starting with the basics, and as far as I can see, the preliminary diagnosis when key works better than the "external input from the keyless RF system", aka the fob, is the same issue I had.

I'm also aware that he says some doors lock, some do not, but replacing batteries and checking connections is a far less invasive measure than ripping out trim and checking individual switches, microswitches, motors, temperature change variables and so on. My tip here is not the be-all, end-all, and the next step should definitely be your suggestion, but I think mine's a far better starting point.

- S

[BEJinFbk]

First of all, I'm not suggesting ripping anything apart...
This is simple diagnosis. Leaving the remote out of the
process reduces variables and simplifies things.

And yes, I read that he's been swapping master switch
panels in the driver's door, but the only thing in that
panel that's part of the CLS is the lock/unlock switch.

The key cylinder switch is also a lock/unlock input, but
it's a two stage Input that unlocks the driver's door on the
first turn and the other two outputs ( tailgate and the other
three door) with the second. I suggested using the door switches
because you're checking all of the outputs and lock motors at
the same time and it's just a little easier. It also rules out any
flakey mechanical linkages between the lock cylinder and the
switch in the door latch mechanism.

Hot temperatures are often a factor in marginal door lock motors
and would easily fit this scenario. Some people aren't aware of it.
Just another piece of the puzzle that requires observation only.

[Sommerfeldt]

Read the OP.
He says the remotes have a battery issue anyway. That means the batteries in those will have to be replaced regardless of what happens.

Why, again, would you rather he "forget" about the remotes and start removing door trims and switches and motors and whatnot, instead of doing one simple thing (possibly two, if checking that the receiver connections are OK) first that will have to be done no matter what happens?

- S