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Tim West
Tim West, ASE Certified Technician
Category: Ford
Satisfied Customers: 4638
Experience:  ASE Certified Service manager of Firestone
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If I have a dtc of P0622 does that mean that I have bad wiring

Customer Question

If I have a dtc of P0622 does that mean that I have bad wiring going to my alternator and need to switch out the wiring harness. I recently replaced my alternator with a PA performance alternator. Do I need to switch out the wiring harness and how do I switch it out?
Submitted: 7 years ago.
Category: Ford
Expert:  Tim West replied 7 years ago.
Access the alternator, test the Red voltage supply wire, this should have battery voltage at all times.
Unplug the 3 pin connector, check pin 3, Orange and Light Blue wire, this should have battery voltage at all times from fuse 43 in the under hood fuse box.
Ensure battery cables are secured on power and ground side and there is no corrosion.
Leave the alternator unplugged, access the PCM located in the right front of the engine compartment, unplug the PCM connector.
Voltage drop test the following circuits between the PCM and the alternator, ensure also the following circuits are not shorted to each other.
Yellow and Light Blue wire, pin 13 at PCM, pin 2 at the alternator.
Yellow wire, Pin 5 at PCM, pin 1 at the alternator.
If all the circuits to the alternator pass, and the circuits between the PCM and the alternator are good, suspect alternator. If the concern is still present, suspect failed PCM.

Hang on I will get pics

Edited by Tim West on 7/8/2010 at 9:43 PM EST
Expert:  Tim West replied 7 years ago.
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Customer: replied 7 years ago.
Would corrosion on the battery terminal make dtc P0622 appear?
Expert:  Tim West replied 7 years ago.
Yes, well kinda, Add an auxiliary ground from the alternator body to the battery and from the body to the battery to see if any change. Add auxiliary ground and leave it in place.
Customer: replied 7 years ago.

If you do a voltage test on the alternatpr what should the DCV voltage read?

Expert:  Tim West replied 7 years ago.
do you mean what should the output of the alternator?
Item Specification
Voltage 12 volts
Generator amps 80/135 amps (max) @ 1,800-6,000 generator rpm,approximately 500-2,000 engine rpm

Generator

Load at 2,000 rpm 80 amps
No Load at 2,000 rpm between 13.2 and 15.5 volt