The codes are as follows:
P0622 - GENERATOR FIELD NOT SWITCHING PROPERLY
P1682 - CHARGING SYSTEM VOLTAGE TOO LOW
So obviously something is not reading correctly in the charging system.
Where did you test the output of the alternator? Was it directly at the alternator or at the battery?
Great, can you check at the battery also?
Also measure the voltage between the battery + and the generator output terminal.
Slow and steady wins the race here :) Lets just step through the diagnosis to see where we get.
Disconnect the PCM and the generator to measure resistance on the two wires shown below. Measure from end to end and then from one wire to the other. Finally measure from each wire to ground. Let me know the results. You must test when the vehicle is experiencing the problem.
Neither wire should have continuity to the other one and neither wire should have continuity to ground.
From end to end should measure close to 0 ohms.
Yes they plug into the alternator/generator.
Connector 2 pin 10 is a dark green wire (DG)
Connector 3 pin 25 is white with a dark blue stripe (WT/DB)
Ok Ed, I took the vehicle out for a hard drive and could not make it do the exact same thing but I did notice that the voltage was low, 12.04. So I did your checks as requested and found that the continuity was fine and the line to grounds were at infinity Ω's I thought I would check the battery sensor as well and found it to be 220k to 240k Ω, seems a little high to me but I do not know the normal values. In addition I noticed that the battery voltage never changed while the sensor was disconnected and the charge rate remained at 12.04VDC. The engine off voltage of the battery is 12.48 After doing the checks I reconnected the PCM and the batter sensor and restarted the vehicle and the system came back to normal, check engine light cleared (from disconnecting the sensor) and the error codes cleared as well. If as I stated in my original post, the output voltage at the Alternator was 13.00 +/- when the dash gauge indicated "0" wouldn't this indicate that the PCM control for the alternator is functioning correctly? Your thoughts?
Yes, I was thinking the alternator is being commanded correctly, but the signal is not getting back to the PCM.
If the voltage is 14 volts at the alternator but 12 at the battery, that has me concerned. Did you remeasure the voltage at the alternator when the battery was only reading 12V?
I made it home. The battery voltage is decreasing, the alternator is not charging, it was 11.8 vdc when I got home. So, I re-did the checks you sent and all was fine as before. I decided to hook up my volt meter to the battery and start wiggling wire harnesses and BINGO the C2 connector on the PCM apparently has a bad connection, (probably on pin 10). The alternator started charging. I took it out again for a test ride and AGAIN the voltage dropped to "0", I turned around and went back home and with the engine still running and the volts at zero I tested the battery with my DVOM, 11.7 volts. Then I moved the C2 connector and I could hear the alternator started working, the volts went to 13.7. Shut everything off and removed the connector and the wire cover to the back of the connector and closely inspected all wires and pins, no apparent loose or broken wires. Sprayed some contact cleaner on the connector and reassembled. Fired it up and went for another ride, 10 minutes into it the voltage dropped again, this time I shut the engine off and restarted and it came back to 14 volts and stayed there for the remainder of the trip home again. I will see how it goes tomorrow, but I am suspecting a pin problem on the PCM...
Glad you made it home!
Before you blame the PCM as the culprit, make sure the pins in the connector didn't get spread open when you were checking the resistance. I use special adapters to check the terminal tension. Without these, you will have to fabricate something that looks about the size of the PCM pin. Then use this tester to see how much drag is on a couple of the good pins. After that compare the drag to the suspect bad pin.
If everything checks out ok, you may be able to open up the PCM and resolder the connections. I have fixed a few PCM/ECMs this way. Yours might be screwed and glued which will make it harder to open.
If you do decide to get a used PCM, let me know your zipcode and I will see what is available near you.
To make sure I locate the right PCM, this is a 5.9L right? Also, is it federal or calif emissions? It would say on the label under the hood.
Just so you know, even after you accept and leave feedback you can return to this question.
Ok, here is the list of what I could find. I have dealt with Don's in Binghamton NY on several occasions and they always treat me right. Only ever had one problem when they shipped a headlight for a different vehicle.
Ok ,off to bed.. keep me in the loop until this is 100% solved!