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Just bought a 2012 Cruze (automatic) two weeks ago. Last week, had a time when it seemed the brake booster would not work. Took to the dealer. Here is what they wrote up:
"test drove did not have the issue described happen to me, however the vacuum pump would not run when eliminating the vacuum from the booster, attempted to run the pump with the function test and pump would still not run. connected another power source and ground and pump ran fine, found an issue with the contacts within the micro switch on the brake booster, repaired contacts and retested with no problems."

What does "an issue with the contacts" mean? What does it mean to "repair contacts"?
 

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the terminal leads for the micro switch. Its metal that allows current to flow to the switch. Like the prongs on a plug that you put in your wall at your house from any electrical device.
 

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But the prongs I plug into the wall do not need "repaired". That's what I'm trying to figure out. How do you repair a contact?
 

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Depending on the design of the contact it can be anywhere from using a standard pencil eraser to clean off corrosion to physically bending them back into place. I've done this multiple times over the years on various computer equipment.
 

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Would anyone else be uncomfortable with that description for the repair of their brakes?
I wouldn't, knowing what I do about electronics.
 

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Would anyone else be uncomfortable with that description for the repair of their brakes?
I wouldn't be too concerned now that it operates as designed.

Speculation: Most of the Cruze build, 2011/2013 with the 1.4t were recalled for replacement of the switch you describe.
They were recalled for the situation you experienced.....minimal power assist.
The original switch design apparently allowed moisture to work its way into the contacts, insulating them.
The new switch has a more robust seal.

I speculate that when your recall was performed the tech. may not have gotten the wire harness securely seated on the new switch, allowing a bit of corrosion/resistance to occur over time.

The mechanic that looked at your car determined that the switch functioned correctly but the current wasn't being fed into the harness leading to the vacuum pump.

He corrected the problem, likely by cleaning the terminals and tightening the female side of the connector......or, as your repair order states, it was repaired.

In our business, repair is a general term that means a fault was corrected without need for part replacement.

Enjoy the car....and I think you have a good repair shop that does not indescriminatly replace parts.

Rob
 

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Vacuum brake boosters of course work on vacuum, normally supplied by the intake manifold. Vacuum increases drastically when you take your foot off the gas as the vane in the throttle body closes.

But in the case of a turbo engine, instead of getting say 20"/Hg of vacuum, will get up to a 15 psi of positive pressure, but only when you hit the gas. That vacuum switch monitors the intake vacuum, when negative pressure, inoperative, but with positive boost, cuts off the intake vacuum and switches to an electric vacuum pump. That switch also beside changing the source of the vacuum, energizes the vacuum pump.

In regards to contacts, actually dealing with two different sets. One set is inside of the switch and inaccessible, sealed in plastic. Can visualize these by holding your forefinger over your thumb and touching the tips of your finger and thumb together. This makes an electrical connection that should switch on the pump.

The other set is in a connector block that connects to the vacuum switch, apparently your mechanic is talking about these. Now its a good question why they became corroded in the first place, should have a rubber seal. Typically what happens is if someone pulls that connector out at an angle, the tabs in the female spread that will cause a poor contact. Connectors should only be pulled straight out and pushed in straight in.

Heck, with used vehicles always have to remove a bunch of connectors, use a very fine pair of needle nose pliers, and close that crimp in the females. Because guys that work on these things don't know what they are doing, like to rock them out, this is a no-no.

Besides all this, also have an all important check valve in the brake booster itself where air can only flow out. A real simple test to know if yours is good. Let the engine idle at night, then switch it off without touching the brake pedal. The next morning, without starting the engine, should be able to press your brake pedal three times with power assist. You can tell this, because the brake pedal will come up and be very firm and should only go down a fraction of an inch.

If its real hard and firm at the first pressing of the brake pedal, have a bad check valve, and with this, may not get any power assist at all while driving.
 
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