It’s difficult to name a system on a newer vehicle that isn’t electronically regulated or controlled and that means, more than ever, that a malfunctioning charging system can affect the entire vehicle and not just affect the initial start-up. So when they do go wrong, customers tend to notice and bring the vehicles in right away for repairs – great, but diagnosing and repairing those newer charging systems can be quite a challenge.
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In fact, on newer vehicles, a faulty charging system can cause problems ranging from no-start conditions to MIL lights coming on intermittently and even cause accessories to occasionally stop working.
Additionally, charging systems on newer vehicles are much less tolerant of any problems than they ever used to be, and diagnosing them successfully means being aware of how seemingly small variations between measurements and specifications can actually mean the difference between normal vehicle operation and a drivability nightmare – even on vehicles designed for severe-duty conditions and very rough service. The basics are still there – battery, generator, connections and control – but how each system is diagnosed has definitely changed. And it’s important to know how to figure out what’s wrong.
No worries. Here are a few examples and solutions to common and uncommon problems to make diagnosis as straightforward as problem-free as possible.
As ever, successfully diagnosing charging system problems begins by inspecting the battery – because if the battery isn’t within manufacturer specifications the rest of the charging system cannot be reliably tested (which can be a challenge when a vehicle is towed to the shop with a dead or drained battery).
If there’s ever a question, inspect and charge the battery according to service information – including reviewing tech tips and service bulletins – and then when the battery is known to be good and within specifications, proceed to test the rest of the charging system. This is so important that even if the battery looks new or has been recently replaced, it’s still critical to ensure that the battery is OK before proceeding further with any diagnosis – charge it according to specifications if needed, check quickly for things that would likely drain the battery like the block heater or cord not working, a missing serpentine belt, or even that something was left on and only then continue with charging system diagnosis.
This step is important and not to be skipped for two reasons.
The first reason is that battery problems can easily be mistaken for drivability concerns – and often are – and there’s just no point wasting time chasing something that can easily be repaired.
For example, one of our clients recently texted us because their Chevrolet 4x4 truck needed to be boosted after the door was left ajar and the MIL light then came on while driving. Replacing the battery fixed both the no-crank concern and the MIL problems, which took him completely by surprise because he couldn’t make the connection between the truck’s older, weak battery finally failing and the MIL coming on while driving. (I told him he was free to replace more parts if he wanted to.)