C2103 CODE

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philiproots

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2006 KJ, V6, auto, 2WD: Changed the fuel pump when i purchased the vehicle about 6 months ago with a cheapie from Amazon...everything fine until a couple of months ago. Have since been experiencing stalling while driving that got more and more frequent until one day I was left stranded. Managed to get the vehicle home while the engine was running in 10-20 second intervals. Checked the codes with my BlueDriver OBDII and it read C2103 - System High Voltage which can be caused by battery, voltage regulator, alternator, speed sensors or brake light switch. Changed both rear wheel ABS speed sensors (because I knew those were bad) and now i am getting a C2102 code = System Voltage Low (battery, alternator, voltage regulator, ignition switch, grounding issue). I can hear the fuel pump when i first turn on the ignition and the engine will run for about 10 seconds then shut off - sounds like fuel starvation. It won't start again (no fuel pump sound) for at least another 10 minutes.
Any clues? Shall I try changing the brake switch or should I be looking for a good refurbished PCM/ECU? i did install an aftermarket 3-pin trailer connector - can that cause electrical issues?
 

philiproots

New Member
Joined
Nov 26, 2025
Messages
2
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2006 KJ, V6, auto, 2WD: Changed the fuel pump when i purchased the vehicle about 6 months ago with a cheapie from Amazon...everything fine until a couple of months ago. Have since been experiencing stalling while driving that got more and more frequent until one day I was left stranded. Managed to get the vehicle home while the engine was running in 10-20 second intervals. Checked the codes with my BlueDriver OBDII and it read C2103 - System High Voltage which can be caused by battery, voltage regulator, alternator, speed sensors or brake light switch. Changed both rear wheel ABS speed sensors (because I knew those were bad) and now i am getting a C2102 code = System Voltage Low (battery, alternator, voltage regulator, ignition switch, grounding issue). I can hear the fuel pump when i first turn on the ignition and the engine will run for about 10 seconds then shut off - sounds like fuel starvation. It won't start again (no fuel pump sound) for at least another 10 minutes.
Any clues? Shall I try changing the brake switch or should I be looking for a good refurbished PCM/ECU? i did install an aftermarket 3-pin trailer connector - can that cause electrical issues?
Forgot to mention battery was almost new when I got the vehicle and i have changed out the battery post cable clamps.
 

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