Voltage drop on engine rev

flyboy210

New member
2014 Sprinter Diesel 3.0L with LTV camper on the back and 13K miles. Dealing with some low voltage error codes popping up and subsequent ABS/EPS/Traction control systems being flagged and disabled. Took a look at overall system voltage, so I put a multimeter on the system and noted 14.1v on idle, which is fine. But when I revved the engine a bit, noted voltage dropping to mid 12v range on my FLUKE. This consistently happened repeatedly when making small revs on the engine. I don't find this normal and wondering if the alternator or regulator are going bad or if some load is kicking in when engine rpm increases above idle. Curious for any thoughts on the matter. Thanks.
 

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4wheeldog

2018 144" Tall Revel
My first thought is that the alternator is failing. You might check the voltage to see if the drop is at the source (The alternator). If you are showing full voltage at the alternator with the engine running 2000 rpm, then it may be a ground or resistance somewhere. Regardless, the alternator should have enough oomph not to drop voltage, no matter what load the vehicle puts on it.
 

Rob S

2008 Navion J on 2007 V6
Hmm, could be bad wiring connection or bad ground as well, increased vibration at higher rpm causes it to fail.

Might be able to confirm by testing right at the alternator, compared to further down the system
 

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