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Old 11-30-2009, 03:59 PM
Junior Member
Join Date: Nov 2009
Posts: 1
Question '98 MPV Alternator Woes

Please bear with me as I describe my '98 MPV electrical woes.

The AutoZone guys ran their diagnostics on my electrically weak MPV and determined the battery was good, but alternator had gone bad. $150 and several skinned knuckles later (I won't even detail the poor Mazda engineering that requires approximately 2/3 of the vehicle to be disassembled to reach a commonly replaced part), I have a brand spanking new (reman) alternator installed and running. Woohooo!

I take it for an extended test drive and find the battery light coming on (and oil/at light) after about 10 minutes. Ugggh. I take it back to AutoZone, where they diagnose that the Alternator is not generating any electricity. I understand the alternator must receive a 'signal' to kick on to start generating, so I pull out the multi-meter and start troubleshooting.

Testing with vehicle not running:
- Voltage at the battery is 12.1.
- Voltage at the big wire on the alternator is 11.98
- Voltage at lead 1 on alternator: 11.97
- Voltage at lead 2 on alternator: 0

Testing with key turned on, but vehicle not running:
- All measurements were similar except for:
- Voltage at lead 2 on alternator: 10.99

Testing with vehicle running:

- Voltage at the battery is 12.0.
- Voltage at the big wire on the alternator is 11.94
- Voltage at lead 1 on alternator: 11.91
- Voltage at lead 2 on alternator: 10.92

So, back to AutoZone I go. Their alternator tester is bad, they agree that my measurements show a faulty alternator, so I swap the new/bad alternator for a new/good alternator. Back under the hood I go, although this time the process was quicker, yet still unpleasant. I start 'er up after tightening the last bolt, do some quick measurements, and find the same problem exists. Double uggggh!

I am totally lost... and frustrated (especially thinking that the original alternator was not bad, but has already been shipped back to AutoZone reman world). My mediocre knowledge of Automobile electronics tells me that everything should be working fine, yet it isn't. I tend to think it has something to do with Mazda electronics at this point, but don't know enough to continue troubleshooting. Please, please, please... can anyone help me understand what I am missing here? Any suggestions as to the possible problem, or things to try next will be appreciated. Greatly appreciated!

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Old 11-30-2009, 03:59 PM

98, alternator, bad, battery, checking, del, install, mazda, mpv, remove, signs, test, testing, voltage, walkthrough

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