P0621 Code
05-01-2016, 04:41 PM
#1
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Join Date: 12-20-2009
Location: Redlands, CA
Posts: 49
P0621 Code
My wife started up the car to go shopping and the car started singing and gave her the battery light on the dash. I hooked up my scanner and pulled a P0621 code. This seems like a " it could be anything code" related to the ECM. I recently changed the battery ( about a month ago) the original battery finally started to die. Other than that no work on the electrical system.
I will start checking battery voltage, the connections at the alternator and connections at the ECM modules.
Anyone have any other suggestions?
I will start checking battery voltage, the connections at the alternator and connections at the ECM modules.
Anyone have any other suggestions?
05-01-2016, 05:07 PM
#2
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Join Date: 05-01-2014
Location: California
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Looks like battery or alternator.
But as reported here: EFI Live autocal versus the code reader. P0621 P0128 - Chevy and GMC Duramax Diesel Forum some readers incorrectly report P0621 when the code is actually P0128, which points to the thermostat.
But as reported here: EFI Live autocal versus the code reader. P0621 P0128 - Chevy and GMC Duramax Diesel Forum some readers incorrectly report P0621 when the code is actually P0128, which points to the thermostat.
05-01-2016, 05:16 PM
#3
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Sounds more like the ECM reading the alternator demands, per this link
P0621 Chevrolet Generator Lamp L Control Circuit Malfunction OBDII Engine Light Trouble Code | Engine-Codes.com
P0621 Chevrolet Generator Lamp L Control Circuit Malfunction OBDII Engine Light Trouble Code | Engine-Codes.com
05-01-2016, 05:32 PM
#5
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Join Date: 12-20-2009
Location: Redlands, CA
Posts: 49
I did change the thermostat, coolant and hoses about 6 months ago after getting a code regarding temp.
oldblue Alternator is on the list and is the first thing I thought it could be before hooking up the scanner. I'm checking that. It's just such a vague code that I can end up on a wild goose chase.
Wanted to check in to see if anyone has run in to it before.
05-01-2016, 05:35 PM
#7
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Sorry, damn auto correct... I meant "Dinging" as in the the warning chime / bell went off in the car.
I did change the thermostat, coolant and hoses about 6 months ago after getting a code regarding temp.
Alternator is on the list. I'm checking that. It's just a vague code. Wanted to check in to see if anyone has run in to it before.
I did change the thermostat, coolant and hoses about 6 months ago after getting a code regarding temp.
Alternator is on the list. I'm checking that. It's just a vague code. Wanted to check in to see if anyone has run in to it before.
05-01-2016, 05:40 PM
#8
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Location: Fredericksburg,VA
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What is vague about it?
P0621 Chevrolet Generator Lamp L Control Circuit Malfunction OBDII Engine Light Trouble Code | Engine-Codes.com
Seems darn clear to me. The circuit inside the alternator that sends an receives the "turn on" signal is broken.
I guess it could be the control wire or contacts are bad, or the ECU is bad (remote possibility).
P0621 Chevrolet Generator Lamp L Control Circuit Malfunction OBDII Engine Light Trouble Code | Engine-Codes.com
Seems darn clear to me. The circuit inside the alternator that sends an receives the "turn on" signal is broken.
I guess it could be the control wire or contacts are bad, or the ECU is bad (remote possibility).