P0622 charging system fault 03 Grand Marquis

[Witsend]

Customer brings car into shop with a red battery light on and P0622 code is pulled ( with no check engine light illuminated. The car is hooked up to a good battery and charging system analyzer and no problem is found with the charging system test results. Customer claims to have bought the car cheap for $600 needing the battery charged and and a new alternator and went to salvage yard and got a $10 used alternator off a 2001 Crown Vic because there were no 2003 s available at the time. The alternator had the same connector and fit exactly.
Mechanic A checks the wiring diagram of a 2001 crown Vic and a 2003 Grand Marquis and advises customer that despite having the same style connector the 2003 has more advanced charging system externally control by PCM , and the 2001 Crown Vic has the charging system built into the alternator's regulator rectifier assembly. He tells the customer he needs to start with installing a correct new or re manufactured $175 alternator to see if it will fix the concern and if not, verify integrity of the wire from the alternator plug to the PCM and possibly need an expensive new PCM and be reflashed with a J box and a paid Ford Subscription, because the incorrect alternator might have already damaged the pcm
Mechanic B says that as long as the car runs fine charge indicator needle don't drop down below the middle and the check engine light doesn't come on (or make you fail the emission test), who the F@ck cares if the pcm doesn't have external control over the alternator any more , and what if the PCM is bad and needs to be replaced for want of charging system control that went kaput? Put a piece of electrical tape over the glowing red battery indicator and don't worry about it, if it's charging ok.
Who is right ? Mechanic A or Mechanic B?

[greasybob]

Is this your daughter driving the car ? Or any else's son or daughter or wife ? Do you drive on the same roads as this car does ? In any event fix it right and make the world a safer place. If you share the road with others ...... it's not all about you.

[GypsyR]

Well there's a bit more than a simple choice going there but basically mechanic A wants to repair the car correctly. Mechanic B isn't doing quality work that can be warranteed.

And just an FYI, the "computer controlled" Ford "4G" alternator works fine as a retrofit and does not need a PCM to function correctly. I personally put one in a '67 Mustang for example. I believe the next newer version does require the PCM's input though.

[Witsend]

Well there's a bit more than a simple choice going there but basically mechanic A wants to repair the car correctly. Mechanic B isn't doing quality work that can be warranteed.

And just an FYI, the "computer controlled" Ford "4G" alternator works fine as a retrofit and does not need a PCM to function correctly. I personally put one in a '67 Mustang for example. I believe the next newer version does require the PCM's input though.

Obviously a used salvage yard alternator installed by the DIY customer is not going to be warranted by either technician A or mechanic -hack B whether it came from the correct model year car or not.
Tech A wants to ensure the wrong part gets changed out and the job is done right no matter if the pcm needs to be changed for the new alternator to work or not and what final cost ultimately will be, the job is done right so there will be no red battery idiot light on dash.
Mechanic- Hack B However after the battery and charging checked ok , figures if indeed the wrong alternator is working just fine albiet a red battery light but a good chance it took out the internal control circuitry of the PCM , he figures if the PCM control capability is gone, the new replacement alternator that relies on the PCM control to work and may need to reinstall the incorrect junkyard unit back on it because the customer needs the use of their car over the Holiday weekend trip. Tech A , Mechanic-hack B, and the customer get into the driver seat of their $600 beater with electric tape over the light and say F@ck it till Tuesday.It's the Holiday weekend If it works, don't fix it Have a good Memorial Day Weekend Everyone , I'll fix this one right, I'm my very own worst customer.

Is this your daughter driving the car ? Or any else's son or daughter or wife ? Do you drive on the same roads as this car does ? In any event fix it right and make the world a safer place. If you share the road with others ...... it's not all about you.
Reply With Quote

BTW Yes it was all about me , Tech side of me versus the hack side of me with a cheap used car I bought for myself.

[greasybob]

The problem with driving around with idiot lights on is that now you don't know when things have gotten worse. What you thought was a small evap leak is now a lean condition with a fuel pump about to **** out. The battery light is on because of the wrong alternator but how do you know it's still charging ? Unless it also has a volt meter. It leaves you stranded, no problem. it konks out merging onto the freeway or the middle of a busy intersection ?

[Witsend]

The problem with driving around with idiot lights on is that now you don't know when things have gotten worse. What you thought was a small evap leak is now a lean condition with a fuel pump about to **** out. The battery light is on because of the wrong alternator but how do you know it's still charging ? Unless it also has a volt meter. It leaves you stranded, no problem. it konks out merging onto the freeway or the middle of a busy intersection ?

I hear you .It does have an analog cluster with a charge indicator so I'm ok there. With the original alternator though It drove fine for a day with no red battery warning showing and the next day in the morning I had to jump it with the jumper pack to move it and the car was running for a few minutes with the jumper box attached and the charge indicator was well below the middle and volt meter confirmed battery voltage and that there was no charging going on without the red battery warning light showing . I charged the battery up and it tested ok with my battery analyzer.I went to salvage yard and got an alternator off an 01 crown Vic that works and tests just fine,(black plastic D shaped regulator versus white regulator) but the PCM commands the red idiot lamp to come on after a bout a minute with a working charging system because it didn't confirm a snaggle tooth pattern it liked from the working alternator , but for some reason I didn't see any a red lamp as the battery was going down driving it around day before with the original correct alternator in it, so if Jane Doe or whoever would have been driving old Ford , light coming on just 5 minutes before engine stall probably would have caused a traffic snarl for miles any how like many manage to do just gawking

[GypsyR]

Well now, you also want to think about the difference between stuff you do on your own cars versus what you get on the wide open internet and advise others to do.

As for doing stuff that is basically a hack...I plead the fifth on all that.

[Crusty]

Since the original alternator is junk (maybe), and the donor alternator from the salvage yard puts the light on, there is a possibility that the regulator from the original alternator may have the circuitry the PCM/cluster wants to see.
You may find that you can swap out the regulators.
Not much to lose in trying.

[Witsend]

Since the original alternator is junk (maybe), and the donor alternator from the salvage yard puts the light on, there is a possibility that the regulator from the original alternator may have the circuitry the PCM/cluster wants to see.
You may find that you can swap out the regulators.
Not much to lose in trying.

Well I thought that idea was worth a try, but found out the brushes are integral with the regulator rectifier assembly and the worn out brushes of the correct white rectifier could not be swapped with the good ones from the other , so that shot down that idea, so I and was content to leave the working wrong assembly in car with the battery light taped over for time being until I was at the yard today and grabbed another alternator from a 2003 Town Car with the white regulator rectifier, and swapped out the alternator. After installation and start up,The charging voltage was very low around 12.8 to 13V and battery light did not come on I turned headlamps on , high speed blower with AC on , and rear defogger and voltage did not drop below 12.8volts but was keeping up with loads, but WTF?,but why pcm maintain so low of charging voltage?/

[Witsend]

You know what , Honda has some Goofy charging system strategy I don't quite get how it keeps up with battery loads and maintains a float charge trickle charger voltage that I don't quite get that reasoning as far as getting a battery in a low state of charge back up to a full state of charge as quickly as possible but if you are driving it for a long enough period of time it is better for the battery.
I say if the battery starts going down from my short trips , I say screw it and I*'ll put the wrong one back in and tape over the battery lamp. Yes I can and will out engineer them Ford engineers.

[Witsend]

Weird, a Correct 4G alternator installed on the 03 Grand Marquis, Low charging voltage at alternator stud, no missing humps in pattern, still maintains slightly over battery voltage at idle with high speed blower on, Hi beams, and rear defogger on.
PCM desires 13.9 volts yet sees there is low voltage but not setting a charging system fault , or turning on the battery warning light.For interim I think I'm better off with the alternator from the 01 Crown Vic and put tape over the battery lamp .I don't like the strange unicorn hump on this 4G one though, hmmmm? Guess it's time to actually pin test the rectifier connector back to the PCM connector , can't account for more than a half volt difference the PCM reads battery voltage as 12.06 V and I'm measuring 12.95V at the battery. Maybe this used 4G alternator's regulator is just Wrecktifried?