Power Train Malfunction/Reduced Power Warning Light on 2011 CX-9

[ricupg]

Hi guys, I found a similar post on this site regarding my issue, but it was back in 2011 and I was wondering if someone can give some input.

I recently got the brake power booster, pads and rotors replaced (Brakes weren't doing well). After I got my car and drove it for a bit, the little wrench light came on. I called my mechanic back and he thinks that because the he disconnected the battery and they work he did on the car, the computer may need to be re-synched. So I have to bring it in so he can do that.

Even though the light is on the car is running fine, no shakes or loss of power. I did notice that when I turn the car on the light is off. Then once I put it on drive and it goes past the 2000 RPM the light goes on and stays on.

Do you think the mechanic is correct in his diagnosis or should I tell him to look at something else while he's at it?

Thank you.

 

[voldsom]

Definitely sounds like some sort of electrical gremlin. I think bringing it back to the mechanic is the right thing. They should scan the error code and be able to look up/know what it's telling them.

 

[eskimo0101]

CELs (check engine lights) don't come on just because you disconnected the battery. In fact, it's the opposite. When you disconnect the battery it clears all the readiness monitors and any stored codes and the light can't come on until the system does the various tests that would trip the code. Some test are done immediately while other require what is called a "drive cycle". This is what OBDII considers a drive cycle:

http://www.obdii.com/drivecycle.html

If the light is coming on after work like that my guess is he either didn't hook up the vacuum line correctly when replacing the brake booster or there's a vacuum leak. First step is scanning the code and seeing what the ECU is upset about though. Either take it back to the mechanic or stop by Autozone for a free code read. IMO everyone should have a basic code scanner though since they're less than $20 on eBay. Toss it in your glovebox and then you can read codes any time they pop up.

 

[ricupg]

CELs (check engine lights) don't come on just because you disconnected the battery. In fact, it's the opposite. When you disconnect the battery it clears all the readiness monitors and any stored codes and the light can't come on until the system does the various tests that would trip the code. Some test are done immediately while other require what is called a "drive cycle". This is what OBDII considers a drive cycle:

http://www.obdii.com/drivecycle.html

If the light is coming on after work like that my guess is he either didn't hook up the vacuum line correctly when replacing the brake booster or there's a vacuum leak. First step is scanning the code and seeing what the ECU is upset about though. Either take it back to the mechanic or stop by Autozone for a free code read. IMO everyone should have a basic code scanner though since they're less than $20 on eBay. Toss it in your glovebox and then you can read codes any time they pop up.

Thank you for the replies. I will definitely bring it in to have looked at. As for the code scanner, I always say I need to get one then get distracted and never get one.

 

[eskimo0101]

I missed the part about the rpm surging. I'm almost certain now it's something on the vacuum side of the brake booster install.

 

[ricupg]

I missed the part about the rpm surging. I'm almost certain now it's something on the vacuum side of the brake booster install.

Thank you, I'll be sure to mention that to the mechanic. I just hope it's not something else. I've already spent enough this month on car repairs.

 

[syibrahim]

I have exactly the same scenario

Hi guys, I found a similar post on this site regarding my issue, but it was back in 2011 and I was wondering if someone can give some input.

I recently got the brake power booster, pads and rotors replaced (Brakes weren't doing well). After I got my car and drove it for a bit, the little wrench light came on. I called my mechanic back and he thinks that because the he disconnected the battery and they work he did on the car, the computer may need to be re-synched. So I have to bring it in so he can do that.

Even though the light is on the car is running fine, no shakes or loss of power. I did notice that when I turn the car on the light is off. Then once I put it on drive and it goes past the 2000 RPM the light goes on and stays on.

Do you think the mechanic is correct in his diagnosis or should I tell him to look at something else while he's at it?

Thank you.

Hello,

I have exactly the same scenario as I had the brake booster replaced yesterday and got this wrench light today while I was driving my car to work. I called the mechanic but he doesn't seem have a clear idea about the cause and don't want him to mess up with an already messy jungle of wires! I realized that the booster he installed was Motorcraft, I asked him if this is compatible with Mazda specs he said, it's exactly what Mazda uses! could that be what caused the wrech problem?

Have your mechanic figured out the problem? and should I be worried about it?

Thanks

 

[voldsom]

Hello,

I have exactly the same scenario as I had the brake booster replaced yesterday and got this wrench light today while I was driving my car to work. I called the mechanic but he doesn't seem have a clear idea about the cause and don't want him to mess up with an already messy jungle of wires! I realized that the booster he installed was Motorcraft, I asked him if this is compatible with Mazda specs he said, it's exactly what Mazda uses! could that be what caused the wrech problem?

Have your mechanic figured out the problem? and should I be worried about it?

Thanks

Motorcraft wouldn't be surprising, as a lot of the mechanical bits on the CX-9 are Ford parts (Motorcraft is their parts division). So the replacement part doesn't seem strange. You might suggest to your mechanic the vacuum issue mentioned above by eskimo... Maybe the breaks need a bleed again to get the air out, see what the mechanic says?