hey all new to the forum, fellow sparkie from Ontario Canada having an electrical issue on my 2019 GMC canyon V6, wondering if anyone else has had this issue before or can give me some assistance on diagnosing the issue. when it comes to diagnosing normal electrical problems i understand it but when it comes to these computer controlled Smart charging systems, this isn't my forte
the issue originally started as a single LED headlamp on my driver side being dim and flickering whenever i would hit the brakes battery and charge voltage all seemed fine 12.2volts from the battery and 13.9volts running 14.5at start up for a minute or so before dropping to 13.9 once the battery was charged up. thinking it was just a failed bulb Morimoto sent me two new bulbs under warranty.
While waiting for the new lamps to show up, my alternator failed. charged it up a few times thinking the battery just died because it was -30C and its 6 years old. it stalled out a few times before i talked to my mechanic and we figured it was the alternator.
new alternator, and the new lamps showed up. replaced them and noticed the new lamps were both dimming and flickering randomly on start up for about 5 minutes, then it would settle down and do the same thing.
after further monitoring of the voltage i found that at start up the alternator was putting out 15 volts at start up and settle to 14.5volts, the lamps would flicker and dim randomly over 14.3 volts. replaced the battery with a new AGM battery, and still had the same issue
brought it back to my mechanic and we replaced the alternator again thinking it was faulty, and had the same issue. thinking it was a bad ground, we ran a new #4 ground from the alternator to the negative on the battery. same issue, a week or so after i noticed the battery saver warning would come on. thinking it was the current sensor we replaced the whole negative cable harness since the Current sensor only comes on the negative cable harness. same issue.
when Battery Saver comes on the charge voltage is still normal. eventually with more observation i noticed all the lighting, tail lights and interior dome lights dimming when hitting the brakes.
more testing shows an output from the alternator of 58 amps with a DC current clamp meter, but on the negative where the current sensor is, i'm only reading 7-9 depending on if my heated seats and steering wheel heater is on, disconnecting the new ground that was run the other day, i started getting fluctuations in the voltage depending on engine RPM, at idle is was getting 13.6 on the low end and would spike to 15.3 volts, this morning driving to work, a steady 15.1 volts the whole half hour drive.
according to the 2019 Canyon Body Builder manual, the voltage output from the alternator during regular operation and headlight mode should be between 13.9 and 14.5volts depending on battery state of charge. and be at 14.5 at start up for 30 second before switching mode.
has anyone seen this happening, any troubleshooting tips. i'm thinking its a potential failed BCM but i'm unsure how to go about trouble shooting or noticing symptoms of a failed BCM. something has to be triggering the BCM to tell the ECM to increase the alternator voltage. it cant be the signal wiring to the voltage regulator, when the signal connector is disconnected, the alternator drops to 13.6-13.9 volts output. so the assumption is something is telling the ECM to run the alternator at this voltage
i will randomly for my whole drive get voltages of 15.5 volts which worries me that it'll kill my alternator and or battery.
the issue originally started as a single LED headlamp on my driver side being dim and flickering whenever i would hit the brakes battery and charge voltage all seemed fine 12.2volts from the battery and 13.9volts running 14.5at start up for a minute or so before dropping to 13.9 once the battery was charged up. thinking it was just a failed bulb Morimoto sent me two new bulbs under warranty.
While waiting for the new lamps to show up, my alternator failed. charged it up a few times thinking the battery just died because it was -30C and its 6 years old. it stalled out a few times before i talked to my mechanic and we figured it was the alternator.
new alternator, and the new lamps showed up. replaced them and noticed the new lamps were both dimming and flickering randomly on start up for about 5 minutes, then it would settle down and do the same thing.
after further monitoring of the voltage i found that at start up the alternator was putting out 15 volts at start up and settle to 14.5volts, the lamps would flicker and dim randomly over 14.3 volts. replaced the battery with a new AGM battery, and still had the same issue
brought it back to my mechanic and we replaced the alternator again thinking it was faulty, and had the same issue. thinking it was a bad ground, we ran a new #4 ground from the alternator to the negative on the battery. same issue, a week or so after i noticed the battery saver warning would come on. thinking it was the current sensor we replaced the whole negative cable harness since the Current sensor only comes on the negative cable harness. same issue.
when Battery Saver comes on the charge voltage is still normal. eventually with more observation i noticed all the lighting, tail lights and interior dome lights dimming when hitting the brakes.
more testing shows an output from the alternator of 58 amps with a DC current clamp meter, but on the negative where the current sensor is, i'm only reading 7-9 depending on if my heated seats and steering wheel heater is on, disconnecting the new ground that was run the other day, i started getting fluctuations in the voltage depending on engine RPM, at idle is was getting 13.6 on the low end and would spike to 15.3 volts, this morning driving to work, a steady 15.1 volts the whole half hour drive.
according to the 2019 Canyon Body Builder manual, the voltage output from the alternator during regular operation and headlight mode should be between 13.9 and 14.5volts depending on battery state of charge. and be at 14.5 at start up for 30 second before switching mode.
has anyone seen this happening, any troubleshooting tips. i'm thinking its a potential failed BCM but i'm unsure how to go about trouble shooting or noticing symptoms of a failed BCM. something has to be triggering the BCM to tell the ECM to increase the alternator voltage. it cant be the signal wiring to the voltage regulator, when the signal connector is disconnected, the alternator drops to 13.6-13.9 volts output. so the assumption is something is telling the ECM to run the alternator at this voltage
i will randomly for my whole drive get voltages of 15.5 volts which worries me that it'll kill my alternator and or battery.
