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08-23-2010, 10:05 PM | #1 |
Drives: 2007 4dr Sedan Silver Streak Join Date: May 2010
Location: Montreal, Canada
Posts: 73
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Alternator "tridiode?"
My electric system dummy light came on the other day, so I figured it was the battery since I was told it is weak. So replaced the battery, and they tell me that the "tridiode" on the alternator which "sends the signal to the dash light" is faulty. The symptom it causes is that the electric light comes on when the car starts and goes off shortly afterward, but the system still charges fine. They say to fix it I'd need a new alternator, but since it's charging it's a waste of money to do that.
So my questions: 1 - Is this "tridiode" even a real thing? 2 - Can just the "tridiode" be replaced? 3 - Or is the real problem a corroded contact? Thanks. |
08-23-2010, 10:46 PM | #2 |
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08-24-2010, 10:45 AM | #3 |
Drives: 2007 4dr Sedan Silver Streak Join Date: May 2010
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Darn I missed that. Thanks!
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08-24-2010, 02:24 PM | #4 | |
Drives: '08 5-door Join Date: Apr 2009
Location: Surrey, BC Canada
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Quote:
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08-24-2010, 02:41 PM | #5 |
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On the Yaris, it's integrated into the voltage regulator assembly.
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08-24-2010, 03:45 PM | #6 |
Drives: 2007 4dr Sedan Silver Streak Join Date: May 2010
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He probably called it tridiode because he's French.
CT - Do you think cleaning the contacts as per your alternator break down post, or should I replace the voltage regulator assembly? Also, do you happen to remember what size fittings I would need to replace them with stainless steel the way you did? |
08-24-2010, 03:50 PM | #7 | |
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08-24-2010, 07:44 PM | #8 | |
Drives: '08 5-door Join Date: Apr 2009
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Quote:
On an alternator that does have this component, one end of each of a trio of diodes is connected to the phase windings of the stator, while the other ends are tied together and attached to the regulator. Compare, for example, the ubiquitous Delco 10si alternator, which has a diode trio as a separate component. |
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08-24-2010, 08:34 PM | #9 |
Drives: 2007 4dr Sedan Silver Streak Join Date: May 2010
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So there is no diode trio... so that can't be the problem?
I'm going to try cleaning the external contacts first. |
08-24-2010, 09:13 PM | #10 |
Drives: '08 5-door Join Date: Apr 2009
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Good plan. Make sure that there's plenty of travel left on the brushes. Have a good look at the stator windings and make sure there is no burnt or discolored appearance. If you can, check the diodes with an ohmmeter.
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08-24-2010, 09:41 PM | #11 |
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The drawing of the internals of the alternator does not actually show a diode trio, but an equivalent function circuit is implemented within the regulator assembly. The purpose of the diode trio is to stabilize the alternator output at low RPMs. Your mechanic is working from past experience of why the charge indicator light comes on to have stated that he believed that the diode trio is bad.
Based on the the TSB for the 07, the frequency that the issue has been experienced by people on here with 07s, and your Yaris's symptom which match said TSB, I would most suspect the voltage regulator assembly being the issue. But, if you are going to disassemble it to diagnose it, it makes sense to check everything as mentioned above while you are in there. |
10-01-2010, 10:29 PM | #13 |
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I would call that a bit corroded. Did you have a tough time getting some of the screws out?
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10-04-2010, 06:46 PM | #14 |
Drives: '08 5-door Join Date: Apr 2009
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So, is the original problem solved?
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10-05-2010, 08:52 AM | #15 |
Drives: 2007 4dr Sedan Silver Streak Join Date: May 2010
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The bolts came off with no trouble, I was surprised because of how much corrosion was everywhere.
Since I ended up swapping out the entire alternator I can't say whether cleaning the corrosion off would fix the problem or not. Maybe when I'm bored I'll try hooking it up to an electric motor and measure the voltage to see what happens. It may take a couple months though. |
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