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Kevin, Auto Mechanic
Category: Mercury
Satisfied Customers: 2029
Experience:  Diagnostic technician
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2004 Ford Focus - Experiencing increased voltage (spike) at

Customer Question

2004 Ford Focus - Experiencing increased voltage (spike) at or above 5000 rpm.
Submitted: 12 months ago.
Category: Mercury
Expert:  Kevin replied 12 months ago.

Hi im kevin how high is voltage and where are you testing this ?

Customer: replied 12 months ago.
Hi Kevin. I am testing voltage right at the battery with my digital multimeter. It spikes upwards of 18 volts. That is followed by some erratic instrument cluster activity. Resting voltage is approx 12.7 and idle voltage is 14.5-14.8. Idle voltage is steady up to 5000 rpm.
Expert:  Kevin replied 12 months ago.

Ok this is the regulator failing on your car this is part of the alternator .the alternator will need to be replaced to cure

Customer: replied 12 months ago.
Alternator recently replaced month or so ago because of the same issue. Prior alternator only 8 months old. It actually failed and went high on voltage even at low idle. when it happened I diagnosed this as the issue. I didn't perform the work until the following day and it killed the battery as well. It wouldn't even boost and I had to replace. So both new. the erratic instrument cluster activity was evident even after I replaced the alternator most recently. I only found today that this corresponds exactly with the voltage spike.
Customer: replied 12 months ago.
Could something else be influencing the regulators behavior?
Expert:  Kevin replied 12 months ago.

Not that im aware of il opt out see if another tech has any ideas

Customer: replied 12 months ago.
Thx Kevin