Battery Light (P0620 Generator Conditions Circuit)

[2004XLT]

Battery light was on when I bought the exp. Since then I've replaced the battery, alternator harness, and cleaned all connections.

Light is off after starting and only comes on when I shift into gear or press the brake.

Today I tested with a multimeter and I have around 12.6v charge with the car off, 14.64v running with all accesories and sub/amp powered.

No voltage drop between posts/terminals/wiring/alt/bracket/body ground.

Never had any issues with the car not starting. Battery was replaced for extra CCA (old battery was a small Valucraft with only 405CCA).

Should I check anything else or just have the light shut off?

Thanks

*Forgot to say the alternator is a World Class remanufactured. I think the company is out of business or name changed but the best I could find is that it's a 135A made for the Crown Vic.

 

[stamp11127]

Read the Ford section in the following:

P0620 Ford Generator Control Circuit OBDII Engine Light Trouble Code | Engine-Codes.com

Do you have the wiring diagram for the charging system?

 

[2004XLT]

Thanks stamp, I don't have the wiring diagram for the charging system. Is there anything else I should look into?

I did a resistance test according to this: Part 1 -Ford P0620 Test -Alternator Diagnostic Test

Reading on the meter I'm getting is 1. So I would assume my voltage regulator is the problem.

 

[stamp11127]

I have reservations about that article, it may be accurate but vr's consist of multiple semiconductors. What components are being measured between pin 1 and ground? Where did the spec's of the amount of resistance come from?

If you look at the attached wiring diagram for the 2004 alternator, you will see that pin 1 connects to the collector of a transistor while the emitter is connected to ground. You normally test transistors as diodes, not using Ohms. The collector/emitter connection has very high resistance until current is applied to the base. In this case the base is connected to a microprocessor so we don't know what level of current is being applied, plus we aren't able to test the collector/base connection or the base/emitter connection.

Is that article a valid test of the regulator? I don't know with the information supplied by the author. Most alternators I have bought in the past have included the alternator's output results so the chances of a bad alt have been very low.

Darn pdf file is larger than the limit for a post. I'll send it to your email.

 

[2004XLT]

Much appreciated. I see what you mean about the test in that article, I just thought it might be a place to start.

Are there other ways to test the alt? Or another part of the charging system?

 

[stamp11127]

Check your email, pdf sent.

 

[2004XLT]

Thanks stamp will do Pinpoint Test B tomorrow.

 

[2004XLT]

Looks like I'm going to be buying a new alt to get the battery light off.
Also looking through some old paperwork I had the code read at a Firestone right after buying this car and there was also a code for generator overcharging. Recent testing didn't support this, and operation seems entirely normal. Should I really be concerned about this alternator all things considered?

 

[stamp11127]

The vr inside the alt may be on the way out. You can get by for a while as long as it is charging but not overcharging. I would plan on a replacement in the near future.
Does the paperwork give any additional information on the results of the test? Overcharging being it doesn't shut off or over voltage?

 

[2004XLT]

My mistake, code is P2197 - O2 High Voltage. This was for the oxygen sensor I replaced. The only code regarding the generator was the P0620.

Looking at alternators, are there any aftermarket brands that are better or worse? I would really like to go OEM but if there are other options that perform and last then I would look those. Recently I went with an Autozone fan clutch and it's about as bad as the old one, should have stuck with Ford.