Mechanics

WILL AN AFTERMARKET STEREO BE TOO HARD ON A WITH STOCK BATTERY AND ALTERNATOR?

2005 Pontiac Sunfire • 120,000 miles

Will an aftermarket stereo be too hard on a 2005 Pontiac Sunfire with stock battery and alternator?
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Krstnlndsy
September 18, 2012.



First unplug the original radio and see if everything else works. GM has found a number of ways to bleed money from you after the sale when it comes to radios. First they stopped allowing us to buy radio service manuals and parts because they wanted to lock up all the repairs for their two grossly over-priced repair centers. Next, to prevent people from replacing them with aftermarket radios, they started in 2002 on some models building the Body Computer into the radio so you have to leave that radio in the vehicle. There are "relocation kits" that let you snip the speaker wires for your new radio, then mount the original radio in the trunk. Without that original radio you may not have chimes, cruise control, power windows, etc. On newer vehicles that Body Computer is the master computer that tells all of the other ones when to turn on. Without it the engine won't run, transmission won't shift, and everything will be dead. Got'cha!

As for the charging system, there are all kinds of design defects on GM vehicles already since the '87 model year and they have no intention on fixing them. Four to six replacement generators in the life of the car is not uncommon. The biggest thing you can do when one fails, to prevent repeat failures, is to replace the perfectly good battery at the same time unless it is less than about two years old. These generators, due to the design of the internal voltage regulator, develops huge voltage spikes. As the battery ages it will still start the engine just fine but it loses its ability to dampen and absorb those spikes.

If you're planning on installing a rude and obnoxious stereo to play noise for everyone around you, they do draw a lot of current but not at a steady pace. AC generators by their very nature self-regulate current output and simply will not try to deliver more than they're designed for so you won't damage it in that respect, however the internal diodes, which are already wimpy at best, were never really intended to pass full maximum current all the time. They can handle that for a five-second load test or the occasional high demand from the car's optional equipment but it won't take long to overheat them and have one short. That will reduce the maximum output to exactly one third of its design rating and make the voltage spike problem even worse.

Installing a generator with a higher output current rating might help but then you have to consider the wiring on the car that may not be able to handle that. The wire from the generator's output terminal to the battery, (and the fuse), become the "weak link in the chain".

Unless you're already hard-of-hearing, my suggestion is to leave the original radio in the car until it develops a problem, which it will. Then consider the relocation kit if it's needed, and a nice normal aftermarket stereo.

Caradiodoc
Sep 18, 2012.
Thank you for the detailed reply! I really appreciate you taking the time to answer.
You're right - my cars stock radio has been failing in many ways. It's terribly, to put it lightly. I have an after market system from my last car ('92 cadillac) that I was going to install simply because I have it, but after reading what you wrote I clearly have some decisions I need to make now.
Thank you again.

Tiny
Krstnlndsy
Sep 19, 2012.