door lock issue - 86 burb

[lucastos]

I have a door lock question.. the front 2 door lock switches when pressed down lock all 4 door correctly, but neither of them unlock any of the switches when presses up. This makes me think all 4 actuators can't all be broken, since they work on the lock but not unlock direction. Also both switches work on the lock side but not unlock side.

What other causes might allow both switches to function only on the down lock, and all actuators function only on the lock but not unlock?

Clear as mud, appreciate any advice in advance.

Luke.

 

[chengny]

Door lock relay may not be moving to the unlock position. GM part no. 14056552. Shown as item 15 below:

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Looks like this:

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These are $99 at the dealer. But here's an NOS GM part - pictured above - for $48 on ebay (buy now):

http://www.ebay.com/itm/NOS-77-78-7...rue&rt=nc&_trksid=p2047675.l2557#ht_90wt_1138


Don't get me wrong - I don't know if that's the problem, just a possibility. It just seems unlikely that all 4 lock motors would go at the same time. Are the connections at the relay clean and tight? Do the locks move freely to unlock position when operated manually - i.e. by oulling up on the lock buttons?

 

[VAL]

When I first got my truck, it did the same thing. I cleaned the terminals, replaced the switches and everything was fine after that.

 

[lucastos]

All switches manually move well , they just dont respond on unlock, just lock. I will try the relay... thanks for the tip.

 

[lucastos]

All switches manually move well , they just dont respond on unlock, just lock. I will try the relay... thanks for the tip.

How would I access the relay?

 

[chengny]

It's underneath the dash - on a bracket above and to the left of the driveshaft hump.

Use the images I posted above to help locate it. They are accurate representations of the location and physical appearance.

To positively identify it, have someone operate the locks while you listen/feel for a relay that is responding to the switch.

 

[lucastos]

I think I found it, looks like I will have to remove some lower dash pieces just to be able to remove the relay.