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Have a 2006 Subaru Tribeca with 168K miles and just last week a "er bb" has shown up everytime we start the car and drive it. It is displayed just underneath the MPH gauge and above the actual mileage of the vehicle. No other lights come on like a check engine light etc... Tribeca has been running great no problems, brakes are acting just fine etc.... I have used google and other forums with this code and it seems as if you can get 5 different answers to this so called problem that apparently Subaru doesn't have an exact pin point gauge on what the actual problem is to this code. I have heard brake booster, IBU, vacuum line etc... I have not taken into Subaru yet just for fear of cost and them not actually fixing and or finding out what the actual problem is. I am a mechanic on the side and can do just about anything yet like I've said before nothing else has been a problem with the vehicle so not too worried yet. Any info would be great!
Thanks,
Brian
 

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This code is listed as "Vacuum pump system malfunction" in the table found in the FSM (Combination Meter section) for my '06 model.
 

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avk said:
This code is listed as "Vacuum pump system malfunction" in the table found in the FSM (Combination Meter section) for my '06 model.
I guess my alternative question is what is necessarily wrong then? What if there are no other problems, no other lights that come on (like a check engine), and the vehicle is functioning perfectly except that code coming up. My vehicle has 168K miles on it and I really don't want to sink any money into it. I feel as if the vehicle is running fine why bother cause its more then likely a sensor malfunctioning. If it truly is a vacuum pump malfunction I would think something major would be going on. Peoples thoughts if any please.......or if anyone else has experienced this exact issue.
 

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About a week prior I did a sea foam treatment though the brake booster vacuum line (used 1/3 of the can). Sea foam says that's how you do it as to go through your BB vacuum line. I mean car is acting and driving just as it always has, it just throws this one code, but not a check engine light. Could the sea foam thrown this code or possibly damaged a sensor dealing with the vacuum line? I'm just debating to ride it out as it has been 2 months and feel this will cost in the neighborhood of $500 - $1000 if I go to the Subaru dealer to have this problem (although more of just a pain in the a$$) fixed - all for a sensor problem/malfunction.
 

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There's a used unit on eBay for $100 right now. Seems to be a common UP28 pump made by Hella, p/n 009428081, and there should be many ways to get it. Brand new from Subaru can be had for an online price of about $200.
 

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Howdy,

Wife has a 2010 Tribeca, has about 69,000 miles on it now, but the er bb has been showing for probably 30K or more. Since everything seemed to be OK, i didn't bother with it until my wife told me that sometimes when it is cold, the pedal is hard as a rock and she "had no brakes". Clearly no power assist. I bought the Hella UP-28 from Amazon ( http://www.amazon.com/HELLA-009428081-Performance-Electric-Vacuum/dp/B0030Z666E/ref=sr_1_1?ie=UTF8&qid=1375446436&sr=8-1&keywords=up28+hella ) and installed it this afternoon. Er bb is gone, and all seems well. I thought I might document how I did it most easily for people here, as I made a mistake or two and I would do it much more easily the next time:

The pump is on the right side of the car (passenger side) attached to a bracket that is bolted to what seems to be the transmission / transaxle, just above and an inch or two forward of the right wheel axle. It is below and slightly to the rear of the power steering pump reservoir. It is reachable without removing the engine cover or anything else. There are two 10 mm bolts holding it on, top and bottom, a vacuum hose, and an electrical pigtail w/connector.

I recommend removing the vacuum hose from the unit first. I simply squeezed the metal clamp by hand and pulled it off the pump.

Then remove the BOTTOM 10 mm bolt using just a ratchet and socket (extensions will just make it more difficult). It is impossible to see it from above, so I jacked up the car and saw it from below.

While below the car, there is also a white wire clip holding the old wire. This circular clip holds with a ratcheting action, so you have to pull it back and slide it apart to open it.

The rest is done from above.

Don't remove the top bolt first, as it will make the bottom one harder to get to and to loosen. So remove the BOTTOM 10 mm bolt first.

Then remove the top 10 mm bolt and extract the pump a few inches to expose the wire and connector at the back. The connector has a clip on it to attach it to another connector back there. I found it difficult to remove the clip, so I ended up just pulling it off. Look at the new unit's connector and see how you must press the lever to release it. Press the connector and remove it, and remove the pump from the car.

From above, put the new pump in place on the bracket. The hardest part is lining up the bolt through the pump and the bracket mostly blindly. I found that holding the bolt in place on the pump allowed me to wiggle it around until it found the hole, then tighten it a few threads by hand to make sure it was threaded and not cross-threaded. Then I tightened it up almost the whole way by hand to support the pump's weight. The lower bolt can then be inserted, while rotating the pump in an arc around the upper bolt, until the lower bolt finds its hole and can be hand-threaded and then tightened appropriately.

Then I tightened the upper bolt properly.

Then I replaced the vacuum hose on the pump nipple by squeezing the metal clamp by hand and pushing the hose onto the nipple.

Then I reconnected the electrical connector. First make sure the connector pins and slot/groove line up. Slip them together until it "clicks".

Since I pulled the old connector off of its clip, I used a zip tie to attach the new wire to the harness in that area near where it was. The new pump comes with a new clip, so if you can see / find the old one, then you could remove it and just insert the new one, but be careful, as the new wire may not be as long as the old one (mine wasn't).

Notes:
Old pump also said UP28, but it said Subaru on it, and it had some different part numbers (see pictures).

New pump had slightly shorter wire than old, but the same connector. This won't matter because the old white ratcheting circular clip is impossible to reach anyway. As I said above, I used a zip tie to keep the wire away from hot stuff and connected to another wire harness, similar to how it was originally.

Start up the car and carefully check the brake operation.

- Anti-lawyer disclaimer -
Please remember that this post is not Subaru's shop manual, and if you choose to do this job, don't view these as directions, but rather a short narrative of what I did, so don't come crying to me if something is not right. I am happy to help, but I'm not responsible for your actions, or your skills as a mechanic!
 

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Yes, 600 hours sounds like a short time when you think about actual driving time, but the pump is only supposed to kick in when the vacuum is low from the engine, so a much smaller percentage of time, I'd imagine.

With this pump failing at low mileage (maybe 30K miles on my wife's Tribeca), I am suspicious that perhaps there is another problem, such as a vacuum leak in the brake booster, or a bad check valve or something else that would cause the pump to run all the time and burn out prematurely.

We know that vacuum is highest at idle, so I checked, and I don't think the pump is running when it is idling. I pulled off the vacuum line and I don't feel any suction coming from the pump. I also didn't feel any vacuum coming from the line, so I guess the check valve is OK.

I decided to go the extra mile and dissect the pump. One of the brushes was fused in place against the commutator in it's plastic housing. I could only turn the commutator back and forth a little less than one full circle either way before it stopped. Also, the brush didn't seem to be worn out, and there was not an excessive amount of dust in the motor from the brush. The plastic housing that guides the brushes was melted a bit, and the brush itself seemed burnt, too. The only other thing I thought I could see that may be wrong was that some of the copper windings seemed to be a little darker than I'd expect, so maybe overheated?

I'm no electric motor expert, but it seems like the motor was not running excessively over those 30K miles before this brush seized up, because the brushes were not worn excessively. Perhaps some sort of debris got in there and caused the brush to seize up and short out? I noticed that there is some part of the seal that was not fully circular, and thus might not have been sealing the housing properly. I did not want to tear apart my new pump to compare, so I'll just have to live with it. I think I'll be only slightly annoyed if the new one burns out in 30,000 miles. Hopefully I'll be able to replace it as easily as I did this one.

I sure would like to know if there's any other troubleshooting method to ensure it is done right.
 

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Coulld have been a short circuit between windings in the rotor, with the resulting high current causing the brush holder to melt. Although both of them should have melted in that case, so who knows.
 

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Yes, much of the plastic looks melted indicating high temperature, likely from the conformal coat on the motor winding wearing through due to improper application at the factory and this creating high current leading to high heat.
 

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Yes, 600 hours sounds like a short time when you think about actual driving time, but the pump is only supposed to kick in when the vacuum is low from the engine, so a much smaller percentage of time, I'd imagine.
This is correct... it's an auxiliary pump that kicks on only when the intake isn't providing enough vacuum to the brake system. There are two situations where the pump is turned on:

1) At low vehicle speeds where the brake is applied/released several times in a short time frame causing the difference between booster pressure and atmospheric pressure to be less than 280-290 mmHG.

2) When the difference between booster and atmospheric pressure is less than 355-365 mmHG at speeds above 49 mph.

Depending on your driving habits (and condition of your vacuum hoses), you could - theoretically - drive a very long time without the vacuum pump ever turning on.
 

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Sounds like you know electric motors! Factory defect at Hella, then.

Thank you!

Yes, much of the plastic looks melted indicating high temperature, likely from the conformal coat on the motor winding wearing through due to improper application at the factory and this creating high current leading to high heat.
 

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Yes, we've done lots of driving in crowded city traffic with this Tribeca, so this makes sense.

I've done some more research on how I can recreate the low vacuum condition and cause the pump to kick on, but Subaru wants me to go to the dealer so they can use "Subaru Select Monitor" on it.

Is there any DIY way to give a false low-vacuum signal to the sensor so I can hear/feel the pump operate, and feel confident that the system is working? Hmmmm... I guess I could disconnect the vacuum line to the sensor, but I don't want to throw a low vacuum code to ECU. Or is that just the "er bb" in the first place?

Thanks

This is correct... it's an auxiliary pump that kicks on only when the intake isn't providing enough vacuum to the brake system. There are two situations where the pump is turned on:

1) At low vehicle speeds where the brake is applied/released several times in a short time frame causing the difference between booster pressure and atmospheric pressure to be less than 280-290 mmHG.

2) When the difference between booster and atmospheric pressure is less than 355-365 mmHG at speeds above 49 mph.

Depending on your driving habits (and condition of your vacuum hoses), you could - theoretically - drive a very long time without the vacuum pump ever turning on.
 

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It's extremely difficult to discern when the pump is operating simply by ear inside the vehicle unless you know exactly what you're listening for. If you have a test lamp or similar, you could try wiring it from +12V at the pump to ground to see when the power is being supplied (though this won't necessarily indicate proper function).

You could also wire it directly to the battery to test operation, though you'll have to be careful as it won't cut out on its own when it's at max vacuum (you don't want to blow a seal in the booster or overload the motor), but again, this doesn't necessarily indicate proper function.

The easiest way to get it to kick on through normal operation would be to replicate #1 above... repeatedly apply/release the brake a few times in succession with your foot off the accelerator. When the brake starts to get "hard," you know it is losing vacuum (which should kick the pump on). If you continue to apply/release the brake at the same frequency and notice it getting slightly softer again (or less hard), that's a good indication that your pump has kicked on and is doing its job.

That said, you can monitor both the on/off switch to the pump and the vacuum levels of the booster with logging software (and without having to go to the dealer). Search the forum (or OB forum) for "Romraider" or similar to learn how to do this.
 

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Thanks!

I looked up ROMRaider, and it seems very interesting and useful.

I am, however, about 90% sure that the burnt out motor (factory defect) was the root cause of the problem, so I may just put it to bed unless/until my wife experiences some problem.

Thank you,

Edward

It's extremely difficult to discern when the pump is operating simply by ear inside the vehicle unless you know exactly what you're listening for. If you have a test lamp or similar, you could try wiring it from +12V at the pump to ground to see when the power is being supplied (though this won't necessarily indicate proper function).

You could also wire it directly to the battery to test operation, though you'll have to be careful as it won't cut out on its own when it's at max vacuum (you don't want to blow a seal in the booster or overload the motor), but again, this doesn't necessarily indicate proper function.

The easiest way to get it to kick on through normal operation would be to replicate #1 above... repeatedly apply/release the brake a few times in succession with your foot off the accelerator. When the brake starts to get "hard," you know it is losing vacuum (which should kick the pump on). If you continue to apply/release the brake at the same frequency and notice it getting slightly softer again (or less hard), that's a good indication that your pump has kicked on and is doing its job.

That said, you can monitor both the on/off switch to the pump and the vacuum levels of the booster with logging software (and without having to go to the dealer). Search the forum (or OB forum) for "Romraider" or similar to learn how to do this.
 

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This thread is gold. Now I know what to look for if we ever have that issue. Thanks for the documentation edbikerii!
 

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Good to know! By the way, in the US and likely Canada, this pump is also available as GM/ACDelco part number 20804130. As of right now, that one is $111.44 on Amazon and $116.79+shipping on RockAuto.
 
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