Failing Alternator, Failing Pulley, Shredding Poly V Belt - Automatic Pro OBD II Never Detected These Things

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I have two Automatic Pros, one in each of two vehicles.

One vehicle had a failing alternator. The red battery dashboard light illuminated but the OBD II device never registered a problem. The check engine light did not illuminate.

The other vehicle had a failing pulley that was shredding the poly V belt. As the belt failed, the battery light illuminated, then the power steering failed and the dashboard light told me there was a problem, and finally the engine overheating idiot lights illuminated on the dashboard. But the OBD II device never registered a problem. The check engine light did not illuminate.

Are these occurrences normal? Is the Automatic Pro not designed to diagnose these kinds of things? Does it only deal with "check engine light" situations?

Thanks.
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Posted 2 weeks ago

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Haleigh Knowlton

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> The check engine light did not illuminate.

>  The check engine light did not illuminate.

That is the key bit here. The problem detection on the AUtomatic is an OBD code reader. If there is an OBD code the check engine light illuminates. If it isn't illuminated then the car isn't providing any codes to the OBD port, this the Automatic adapter has no way of knowing.

And yeah, battery and alternator issues don't generate codes on most cars. For most manufacturer's the CEL is for engine (as in the combustion system), transmission, or fuel delivery issues. Whereas stuff like brakes, coolant system, tires, and electrical system will have their own lights. Technically it is possible for manufacturers to have a car make CEL codes for whatever they want, but most just stick to that standard.
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Thanks for the quick reply.  So just to clarify, am I correct in understanding that the Automatic Pro is designed to detect and interpret CEL issues only?  That it's a "check engine light" troubleshooter, and anything else that might be happening under the hood won't be detected or interpreted by the Automatic Pro?  Not that anything's wrong with that, I just want to make sure I understand what it will and what it won't do.  I had assumed that everything that happens under the hood gets transmitted through the port that the OBD gets plugged into!  Thanks again.
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Haleigh Knowlton

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Yeah, it's an inherent limitation of the Automatic utilizing the OBD port. There are the standard legally required stuff that is transmitted, but often other signals on the OBD if they are even there about other parts of the car are non-standardized and proprietary such that the Automatic can't read them.