S70 Power Door Lock Problems

[KeenanMD]

Hey everybody!

I am having a long-standing problem with the power door locks on my 1999 S70 GLT for the past 3 years, both with use of the door switch and the keyfob.

ONLY IN WARM/HOT WEATHER the power door locks, especially the driver's, incompletely lock or unlock. The locking mechanism motor can be heard but they seem "weak" and usually don't fully lock or unlock the door.

I've checked the terminal connections on the locks; the car's battery is new and strong without any other electrical problems in the car. I've lubricated the lock mechanism without any change in performance.

POWER DOOR LOCKS WORK NORMALLY IN COOLER WEATHER including wintertime; I've never had a problem with manually locking/unlocking the doors.

Any ideas? Thanks in advance-

KeenanMD

[VolvoTurbo850]

Move to a place where there is only cold weather ? Sorry had to say it, forgive me!

Is this only when you use the keyfob? Manually with key? Or both?

[BEJinFbk]

Sounds like you need a couple of new latch mecahnisms.

[JRL]

You need a new lock/actuator assy (as many that are bad)
Common failure
You can also buy used assys.

[KeenanMD]

Thanks for the replies-

Doors always lock/unlock manually; during warm/hot weather the power mechanisms don't work with either the keyfob or the armrest lock switch.

The power windows always work fine suggesting it is not a grounding problem.

I understand the actuator assembly is a common failure but why would it be variable with change in temperature?

Thanks for any other ideas!

KeenanMD

[BEJinFbk]

Physics 101 - Expansion and contraction.

[turbozutek]

If the locks don't look likely (or even do this before checking the locks as it's the work of just a few minutes):

Wait till it's hot and problem is apparent. Remove central locking controller module from CEM; throw it in fridge.

20 mins later, sling it back into the car and try locking it. It if helps, suspect dry joints on the unit PCB or burnt contacts on the relay. One of the failure modes of a dry joint is current limitation - which sounds like your 'low power' door locks.

I had a similar problem on a Volvo 480 Turbo a few years ago (of course it only showed up after I'd installed a remote alarm, causing me to spend hours double checking work!).

[homerh]

If the locks don't look likely (or even do this before checking the locks as it's the work of just a few minutes):

Wait till it's hot and problem is apparent. Remove central locking controller module from CEM; throw it in fridge.

20 mins later, sling it back into the car and try locking it. It if helps, suspect dry joints on the unit PCB or burnt contacts on the relay. One of the failure modes of a dry joint is current limitation - which sounds like your 'low power' door locks.

I had a similar problem on a Volvo 480 Turbo a few years ago (of course it only showed up after I'd installed a remote alarm, causing me to spend hours double checking work!).

What do you mean by a "dry joint"? Is there a way to fix this or does the module need to be replaced if it's bad?

[Ozark Lee]

The term "dry joint" is common parlance for a broken or faulty solder joint. They typically get intermittent or temperature sensitive as they fail.

...Lee

[homerh]

Can anybody recommend a source for a refurbished Central Locking Control Module?

[jblackburn]

Give Erie Vo-vo a call.

[homerh]

I looked under the driver side dash, but can't seem to locate the Central Locking Contol Module. Could describe the exact location and perhaps include a photo so I know exactly what it looks like?

[BEJinFbk]

I looked under the driver side dash, but can't seem to locate the Central Locking Contol Module. Could describe the exact location and perhaps include a photo so I know exactly what it looks like?

I still think you're in for new latch mechanisms, but
here are a few pages that may help you get this fixed.
I had to split it into 2 PDF's, but it's all here.

99 S70 Power Locks - diagram A.pdf

(158.71 KiB) Downloaded 506 times

99 S70 Power Locks - diagram B and Component Locations.pdf

(492.94 KiB) Downloaded 445 times

You're looking for module 2/76.

Good Luck!

[homerh]

I looked under the driver side dash, but can't seem to locate the Central Locking Contol Module. Could describe the exact location and perhaps include a photo so I know exactly what it looks like?

I still think you're in for new latch mechanisms, but
here are a few pages that may help you get this fixed.
I had to split it into 2 PDF's, but it's all here.

99 S70 Power Locks - diagram A.pdf

99 S70 Power Locks - diagram B and Component Locations.pdf

You're looking for module 2/76.

Good Luck!

Thanks for your reply. I have a 98 GLT, but the schematics are for a 99. Are they the same? Can you point out which component on both diagrams is the Central Locking Control Module? Also, is there a separate relay in the system?