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Discussion Starter · #1 ·
Hello, this is my first post. I did search the forum and didn't find anything relevant in the first few pages.

Vehicle: 2007 TSX, 103k mi. Recently purchased for my son to use for college. Car is in great shape. New battery and alternator in last 3 months.

Problem: When decelerating, between 30-20 mph, the "Check Charging System" error appears in the central information display, and the battery light illuminates. This lasts only a few seconds at most.

Details: charging voltage is normal at idle, 14.3 V. I have checked the alternator plug, both battery cables, and the negative battery ground connection. All are tight and clean. And here is the interesting thing: the error message will only appear if the car is decelerating and IN GEAR (this is the 5AT). If I drop into neutral during deceleration, the error will not appear. And if decelerating in neutral, I can reproducibly trigger the error by dropping the tranny in Drive.

Any suggestions for how to trouble shoot this? I'm thinking that the issue is mechanical, either a faulty harness or ground connection, and triggered by the engine/transaxle torquing on the engine mounts during a downshift.

Thanks in advance!
 

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I ran into a random charging/battery light issue with my '06 6MT this past November. I dealt with it pretty quickly, so never established exact behavior patterns.

It went (and stayed) away after I cleaned up/re-torqued all of the ground connections (couple were sketch after 140k miles) and dielectric re-greased connectors suggested by my mechanic (coastal rains during winters). I since also swapped over to an Optima Yellowtop, which made an unrelated noticeable difference. Been peachy since ever since.

Good luck!
 

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Discussion Starter · #3 ·
It went (and stayed) away after I cleaned up/re-torqued all of the ground connections (couple were sketch after 140k miles) and dielectric re-greased connectors suggested by my mechanic (coastal rains during winters).

Good luck!
Much thanks for the reply. I am only aware of two ground connections--from the battery to the body, and from the block to the body on the other side of the engine. Are there more I should check?

Thanks!
 

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Discussion Starter · #4 ·
An update on this:

1) I located, removed, cleaned, and reinstalled all three grounding straps. All three were in great shape, and had very good metal-to-metal surfaces with no obvious oxidation.

2) I disconnected, wire-brushed, and reconnected both battery post cables. No corrosion, very clean, tight.

These steps did nothing to address the problem.

3) I bought a cigarette-lighter mounted digital voltmeter, and I can confirm that when the "Check Charging System" light comes on, the voltage drops to around 12.5, for a few seconds only. Then it bounces back up to 13.8-14.2, depending on rpm.

At this point I think I have one of two problems: 1) an intermittently faulty alternator, or 2) an intermittent connection on the wiring harness that runs from the alternator to the battery. The alternator is 3 months old, so unless it was bad at install I doubt that is the case. Anyone have any experience with the wiring harness?

Thanks!
 

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A bad alternator right out the box is not that unusual these days, especially if it is a rebuilt unit. Is it a new aftermarket, rebuilt, new OEM Acura? You might want to have some diagnostics run on it, if possible.
 

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Much thanks for the reply. I am only aware of two ground connections--from the battery to the body, and from the block to the body on the other side of the engine. Are there more I should check?

Thanks!
Sorry did not notice earlier...IIRK might had a lot more 2 connections...which now makes me think whether a prior owner put on a (crappy) grounding kit? Which would also make my case completely different :/

Never had an alternator fail at 3 months, but I won't disagree with Ken's point either. Re-manufactured and/or 3rd party/off-brand parts can be a gamble. I had a cheaper 3rd party alternative of a suspension top hat fail 2 miles from time of installation (bushings pulled through/disintegrated and the whole thing started clunking like crazy).
 

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An update on this:

1) I located, removed, cleaned, and reinstalled all three grounding straps. All three were in great shape, and had very good metal-to-metal surfaces with no obvious oxidation.

2) I disconnected, wire-brushed, and reconnected both battery post cables. No corrosion, very clean, tight.

These steps did nothing to address the problem.

3) I bought a cigarette-lighter mounted digital voltmeter, and I can confirm that when the "Check Charging System" light comes on, the voltage drops to around 12.5, for a few seconds only. Then it bounces back up to 13.8-14.2, depending on rpm.

At this point I think I have one of two problems: 1) an intermittently faulty alternator, or 2) an intermittent connection on the wiring harness that runs from the alternator to the battery. The alternator is 3 months old, so unless it was bad at install I doubt that is the case. Anyone have any experience with the wiring harness?

Thanks!
Hello,

I have the exact same issues. Did you ever solve this? I have changed my alternator once and battery for the third time.

Please let me know!

Many thanks,
 

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Hey, just fixed same issue. Unsure if you ever did. On my 'Starter Sub Wire Harness' that connects starter, alternator, fuse box and battery I found a loose connection. It is gray, 6 pins, and hidden under the manifold (near the starter). Shove your hands under there and try pressing the connectors fully in.

I also changed this wire for a brand new one. Unsure if I had to! Figured out issue once I made the same mistake putting the new one in and not connecting it back properly (semi common apparently).
 

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Hello, this is my first post. I did search the forum and didn't find anything relevant in the first few pages.

Vehicle: 2007 TSX, 103k mi. Recently purchased for my son to use for college. Car is in great shape. New battery and alternator in last 3 months.

Problem: When decelerating, between 30-20 mph, the "Check Charging System" error appears in the central information display, and the battery light illuminates. This lasts only a few seconds at most.

Details: charging voltage is normal at idle, 14.3 V. I have checked the alternator plug, both battery cables, and the negative battery ground connection. All are tight and clean. And here is the interesting thing: the error message will only appear if the car is decelerating and IN GEAR (this is the 5AT). If I drop into neutral during deceleration, the error will not appear. And if decelerating in neutral, I can reproducibly trigger the error by dropping the tranny in Drive.

Any suggestions for how to trouble shoot this? I'm thinking that the issue is mechanical, either a faulty harness or ground connection, and triggered by the engine/transaxle torquing on the engine mounts during a downshift.

Thanks in advance!
Did you ever find the issue ? I’m having exact same issue myself
 

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Did you ever find the issue ? I’m having exact same issue myself
I had this problem for about a year and it would kill my battery and alternator back and forth on and on. It ended up being the positive battery cable. This is a mildly common gremlin that I have seen pop up on this forum as these cars age. Pop a new one on there and see what happens. It fixed my intermittent charging light permanently.
 

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This one of those issues that can be common and have various causes. The fact that it happens when decelerating is telling but also why there are different causes because it gets closer to idle which is at low rpm. I've experienced this issue and my causes were a worn/stretched serpentine belt, a worn tensioner pulley assembly and a bad alternator. All separate issues.Best of luck.
 
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