Chevrolet Cruze Forums banner
1 - 18 of 18 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter · #1 · (Edited)
Hello all!

I have a 2013 Cruze with about 67k miles, and I'm just about at my wits end trying to figure out what's going on with my electric vacuum pump.

The car will sometimes have weak brakes within the first minute or two of running, like, there is no or limited power assist available. After doing some research, I noticed that the vacuum pump would never run (pressing brake a few times while engine is off but ignition is in "ON" position). So, I began diagnosis.

I replaced the fuse for the vacuum pump and swapped the relay, no change. I replaced the pump, no change. I replaced the micro switch attached to the brake booster (three wire in 2013), no change. The pump just won't turn on.

I don't have any wiring diagrams available, so I'm not exactly sure where to go from here. Anyone have any ideas?

EDIT: It's a Cruze LT, with the 1.4L engine and Automatic transmission.
 

·
Administrator
Joined
·
25,596 Posts
I believe there was a recall on the vacuum pump switches. Put your VIN into https://recalls.gm.com and see if this is an open recall on your car.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #3 ·
The recall affected 2011-2012 Cruze models, as far as I know. I checked my VIN and there are no open recalls.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #5 ·
VP switch? Is that the switch that goes into the brake booster with the three wire connector? I just replaced that today with a dealer sourced part.
 

·
Premium Member
Joined
·
8,003 Posts
I replaced the fuse for the vacuum pump and swapped the relay, no change. I replaced the pump, no change. I replaced the micro switch attached to the brake booster (three wire in 2013), no change. The pump just won't turn on.
I think you've changed everything I would have suggested. Pumps and switches are known fail items, but you've changed that. I think you're going to have to go to someone for actual troubleshooting instead of throwing parts at it.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #7 ·
Yeah, that's the conclusion I'm coming to. I figured I'd pose the question to see if there's anything that I missed.

As a last ditch, I'm tracing wires to see if there are any broken wires or corroded connectors.

I'm aware of one relay and one fuse for the vacuum pump system. There are not any more fuses I'm missing, are there?
 

·
Premium Member
Joined
·
8,003 Posts
Might as well check all the fuses. But off the top of my head, I can't think of anything else. Nothing cheap, anyway.
 

·
Administrator, Resident Tater Salad
Joined
·
17,346 Posts
Hmm. The switch SHOULD command the vacuum pump to turn on when vacuum is low. I'm not even sure if that one goes back through the body control module.

My only other thought would be perhaps a check valve in the brake assist system is bad, but if that were the case, I'd think the pump would be running all the time.
 

·
Banned
Joined
·
10,296 Posts
Could be the vacuum booster itself, leaking. Simple test after you switch off the engine at night, before starting it in the morning, should be able to hit your brakes three times before that pedal get hard.

Vacuum is taken off the intake manifold, what about that hose that feeds the vacuum booster, a simple vacuum gauge will show these problems.

Turboless cars do not need that switch and vacuum pump, because the pressure is always negative, altitude can be the culprit, but even at this, minimum vacuum should be at least 6"/Hg.

In a certain sense with a turbo, that vacuum switch and pump is redundant, will only get positive pressure with that turbo when you are hitting the gas, on the Cruze, can be as high as a positive 35 psi! But if you take your foot off the gas, at sea level, that vacuum should increase to at least 20"/Hg, drops an inch for every 1,000 feet above sea level. I am at 1312 feet, so only get close to 19"/Hg.

Really the only time you need that vacuum switch and pump is if you are stepping on the gas and the brakes at the same time, really not good idea. But some people drive this way so the reason for that switch and pump.

Vacuum booster had a check valve in it, can also be tested with a hand operated vacuum pump, should be able to hit 20"/Hg and it should hold. These are the basics.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #11 · (Edited)
I will test that when I get home from work tonight. That will be a good 20 hours since I touched the pedal.

Since I'm like 300 ft ASL, I should get close to 20.

I also got a hold of a wiring diagram for the brake system last night. I'm getting 5v at the switch, and 12v at the pump, so that narrows it down to the signal wire, check valve, or brake control module. I'm not getting any idiot lights, so I don't think it would be a problem with the module.

Edit: The more I think about it, the more I am thinking that the new pump I got may be faulty. That will be added to the list to test.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #12 ·
I have had some success tonight! The pump will run under certain conditions.

I bench tested the old pump again and confirmed it is dead. I then tried pumping the brakes with the engine off but the key on, and I couldn't get voltage through the relay*.

I then thought about it, and remembered reading that if there's a vacuum leak, the pump should run constantly. So I unplugged a vacuum hose and started the car, and got voltage through the relay. Turned the car off and plugged the pump back in. Turned the engine on with the vacuum hose still unplugged and the motor turned on!

That being said, the pump won't run to restore power brakes when the engine is off. There are YouTube videos that show the pump running with the engine off. So that is where I am now.

Do I need to get the brake control module reprogrammed? Is this something that the car will learn, or does it require a trip to the dealer?

TL;DR: The pump now works with the engine running and the vacuum hose unplugged from the brake booster.

* According to the wiring diagram, the power for the pump is always hot, but ground is open when it doesn't get voltage from the VP sensor. When it detects voltage, the relay shorts the ground, completing the circuit. I wanted to put this here for future people searching.
 

·
Administrator, Resident Tater Salad
Joined
·
17,346 Posts
Really the only time you need that vacuum switch and pump is if you are stepping on the gas and the brakes at the same time, really not good idea. But some people drive this way so the reason for that switch and pump.
Cold idle. High valve overlap; no vacuum. Especially while in reverse (tall ratio; ECU compensates by opening throttle)

I then thought about it, and remembered reading that if there's a vacuum leak, the pump should run constantly. So I unplugged a vacuum hose and started the car, and got voltage through the relay. Turned the car off and plugged the pump back in. Turned the engine on with the vacuum hose still unplugged and the motor turned on!

That being said, the pump won't run to restore power brakes when the engine is off. There are YouTube videos that show the pump running with the engine off. So that is where I am now.

Do I need to get the brake control module reprogrammed? Is this something that the car will learn, or does it require a trip to the dealer?
Do you still have the switch you replaced? Wonder if THAT is defective and not detecting when vacuum is low.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #14 ·
Do you still have the switch you replaced? Wonder if THAT is defective and not detecting when vacuum is low.
The reason I replaced the switch was because the new pump wouldn't turn on. I will test the old switch as a sanity check, though.
 

·
Banned
Joined
·
10,296 Posts
That vacuum switch on switches on when the intake manifold drops below about 6"/Hg and only works when the engine is running. Not only switches on the vacuum pump, but switches the power brake booster vacuum from the intake manifold to the vacuum pump.

Vacuum switch can be bench tested with a 12V power supply and a hand operated vacuum pump. When deenergized the line to the intake manifold should be completely opened, and the line to the pump, completely blocked. Just the opposite when energized.

If half way, sticking valve, you have problems.

65 Buick use screws to hold the vacuum booster together, could replace the diaphragm for a couple of bucks, but because it was this way never had problems with it, even after 330K miles. But goodbye to screws, crimped now and throwaway, just one tiny crack in that diaphragm can be the problem, but still can be leak tested. Have to buy a new one if it is.
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #16 ·
That vacuum switch on switches on when the intake manifold drops below about 6"/Hg and only works when the engine is running. Not only switches on the vacuum pump, but switches the power brake booster vacuum from the intake manifold to the vacuum pump.

Vacuum switch can be bench tested with a 12V power supply and a hand operated vacuum pump. When deenergized the line to the intake manifold should be completely opened, and the line to the pump, completely blocked. Just the opposite when energized.

If half way, sticking valve, you have problems.

65 Buick use screws to hold the vacuum booster together, could replace the diaphragm for a couple of bucks, but because it was this way never had problems with it, even after 330K miles. But goodbye to screws, crimped now and throwaway, just one tiny crack in that diaphragm can be the problem, but still can be leak tested. Have to buy a new one if it is.
Interesting. I wonder if that changed from the 2012 to the 2013, when the switch went from 2 wire to 3. Because the 2012 Cruze will definitely turn the vacuum pump on with the engine off. At least, according to the YouTube videos I've seen about this. Don't have another Cruze to test my theory on.

Also, 65 Buick? Nice. We have a 62 Buick Invicta and 63 Buick Riviera.
 

·
Administrator, Resident Tater Salad
Joined
·
17,346 Posts
Interesting. I wonder if that changed from the 2012 to the 2013, when the switch went from 2 wire to 3. Because the 2012 Cruze will definitely turn the vacuum pump on with the engine off. At least, according to the YouTube videos I've seen about this. Don't have another Cruze to test my theory on.

Also, 65 Buick? Nice. We have a 62 Buick Invicta and 63 Buick Riviera.
Yeah, my 12 did. Hmm.
 

·
Banned
Joined
·
10,296 Posts
Way off topic, could toss in my 33 Buick, brakes were all mechanical, or my 41 Buick, was a dream car with Saginaw ball bearing steering, almost as good as power, hydraulic brakes, only one piston the the master cylinder. But the drum brakes used a mechanical forward action to help them grip so really not that much foot pressure was required. But you really had to hit that brake pedal hard when backing up.

Picked up that 33 for 50 bucks, steep for a ten buck car, but only had 16K miles on it. Didn't keep it very long, lacked two creature features like a radio and a heater.

41 was a dream car, easily would do 110 mph, don't ask me how I know this, forgot, with both a radio and a heater, was in the really high 100 buck class. Forgive me about thinking about the good old days. Repairs were also simple.

33buick car.jpg

1941 Buick Roadmaster.jpg
 
1 - 18 of 18 Posts
Top