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Alternator kills radio, antenna

1992 Saab 900S non-turbo.

So, the first mechanic starts welding the oxygen sensor into the newly cut six inch metal pipe from another muffler. He takes a break and a second, younger mechanic gets on top of the engine and does something to the engine. The first mechanic then continues to weld.

Well, according to mechanics 3 thru 6, the first mechanic failed to disconnect the battery prior to welding and killed the alternator and battery. The lead mechanic at this garage said it was a coincidence that the alternator died.

The seventh mechanic installs a rebuilt alternator, battery and four belts.

Now, the problem: The radio can change channels, but no sound comes out of the speakers and the antenna will not automatically go up and down.

Mechanics 8 thru 11 plus a car audio “expert” have absolutely no idea why the radio and antenna do not work. ALL fuses check out fine: inside the engine, under the back seat and two behind the radio. The antenna is basically new and the radio is original equipment.

Can anyone please HELP!!!

They made the mistake of welding on a vehicle that has modules/computers without disconnecting the battery. If there’s not a good ground when the arc is struck with the welder, the arc will look for the next best electrical ground. This could be in a computer/module or I’ve even seen fuel pumps damaged from welding on modern vehicles when there’s poor ground at the welder.

Because some modern vehicles have problems with computers/modules when the battery is disconnected, those who weld on modern vehicles will install this on the still connected battery

I won’t weld on a modern vehicle unless the ANTIZAP is connected to the battery.


Thanks Tester! You’re correct in that that’s how the welding killed the alternator, but my problem is how did replacing the alternator kill the radio and antenna?

There’s a week in between replacing the old alternator and the new in which the radio worked with no problems.

To be fair, this radio is 20 years old. That is extreme old age in terms of electronics, especially mobile electronics. It could be that it’s time is just up. BTW, the radio sends signals to the power antenna when to go up and down. Chances are the radio just gave up and is no longer sending that signal. If the radio worked fine for a week just after this welding incident, I don’t think you can really blame the welding. If the welding damaged the radio, it would have been apparent immediately.

May I suggest Crutchfield for expert advise on your next radio?

I’m a disabled vet on a very fixed income. This fiasco has almost bankrupted me. If I replace the radio and that’s not the problem… Is it possible to criminally prosecute mechanics? If not, why not?

One more… beware of Valero garages!!!

Criminally prosecute? I don’t think that is appropriate at all. Why not? Incompetence is not necessarily a crime. Plus, you’d need a District Attorney or State Prosecutor to sue criminally. Only the government can try a criminal case. If this needs to go to court, it belongs in civil court and simply sue for damages. Anybody can sue anybody in civil court for damages and loss. If you want to go this way, small claims court is probably your best bet. The filing fees are small and most cases don’t require an attorney.

As far as the radio, I’d do a simple test by testing the speaker outputs and power antenna output on the back of the radio with a multimeter before condemning it all together, just to be sure. But, I’m sure this 20 yo radio has probably kicked the bucket and simply needs to be replaced.

“beware of Valero garages!”

I am very sorry for your unfortunate experience with a mechanic who did not know enough to disconnect the battery, prior to arc welding, but I don’t see the validity of warning people to “beware of Valero garages”.
Valero stations are independently owned, and the only thing that they have in common is the brand of the gas that they sell.

I do warn people to avoid chain operations (J-Lube, AAMCO, Lee Myles, Cottman, Pep Boys, Sears, Midas, Monro, Meineke) for maintenance and repairs, but the maintenance and repair facilties at Valero gas stations do not constitute a chain operation in the true sense.

Prosecuting the mechanic was said somewhat in jest since the Valero lead mechanic said they replace alternators “all the time” and “at least three a day.” For a VERY small garage this begs the question, “Is there an alternator epidemic that the CDC and/or AAA hasn’t been informed of?”

Just the same that the five (and counting) mechanics I’ve consulted with agree that it’s not a coincidence that the alternator died after the welding, replacing the alternator and having the radio/antenna die immediately seems far fetched.

If Valero desires to make amends (their garage still has not contacted me like they said they would), they should offer arbitration or a settlement. Instead, I’m going to have to file a civil action where I’ll have to pay a mechanic to testify. This could take months to settle and, meanwhile, I’m out almost $600 and now have no radio.

Is it possible that replacing the alternator and battery shorted out the radio (but still be able to change the channels with no audio and the antenna not going up/down) without shorting out any of the fuses?

I think that you’re assuming way too much here that the shop actually caused these problems. A 21 year old SAAB that still had the original radio working until recently was doing very well.
Radios and alternators go belly-up all of the time and you said the radio worked fine for a week in between the alternator replacement and the radio dying.

Don’t read much into comments from a shop stating they replace 3 alternators a day. That sounds like one of those comments made for dramatic effect; much like the one recently where someone who lost a 2.3 in their Ford was told by their one-horse mechanic shop that they had replaced 6 of those engines in the last 2 weeks.

I hope by welding the oxygen sensor in you do not mean that literally and are referring to an O2 bung instead.
At 11 mechanics, one audio expert, and counting, you really need to settle the car down with one facility. Too many people with their hands in the stew will just foul things up even worse.

ok4450, thanks the thoughts! The radio worked perfect after the oxygen sensor and pipe were welded into place. What failed: the alternator and battery because of the welding by virtue of not disconnecting the battery.

The radio failed IMMEDIATELY after the second mechanic replaced the alternator and battery.

The dramatic effect that the lead Valero mechanic had, in effect, “We commit fraud all the time so don’t worry, relax and enjoy getting it up the…” Unless he was in some warped sense only attempting to lessen his garage’s negligence?

Only two mechanics have touched the car. At this point, I literally can’t afford a third. I’ve only asked around for thoughts on how I got into this economic fiasco and how to get out.

So far, I’m coming up empty and in financial ruins. I’m now out $750: $600 to replace the alternator/battery/4 belts/labor plus $150 the welding job. The car only has 150K miles on it.

The lowest estimate to replace the radio: $250 - - if that’s the problem?

End result out-of-pocket: $1,000 I don’t have because a mechanic forgot to disconnect a battery.

The radio switches 12 volt power to raise or lower the antenna. By disconnecting the connection to the radio you should be able to apply 12 volts to the connection and see if the antenna works ok. Reverse the polarity to change the direction.

There may be a seperate amplifier for the speakers and it isn’t getting power to it for some reason. See if there is any AC voltage going to the radio speaker leads using a meter. If there is a remote power turn on control from the radio that would be another indicator that something is going on with the radio. Make sure power is getting to all the radio connections that require it.

Thanks for the suggestions Cougar!!! It will take some time to check it out. I’ll get back to you!

Courgar (or anyone) could installing a rebuilt alternator have caused any of the various things you’ve pointed out?

Cougar, Thank you again for your response!

However, since you (anyone) haven’t responded and since the mechanic didn’t touch any of the wires you recommended to be checked while he was installing the alternator, the wires are probably not the problem.

I’ve called several car audio shops and all say that they are unable to test the radio/wiring since the car is too old. Some said only a Saab dealership is capable of this. I do not have money for a fishing expedition at dealership prices. One mechanic, though, did state that it was possible to short out the radio without the fuses properly catching an electric surge from the new alternator/battery. So, there’s that.

In the end, I’m going to try to find a used radio at a salvage yard. This, as I’ve learned from the past, ain’t easy for this type/year of car. And again, the radio may not be the problem, but no one has offered a plausible explanation.

Thank you again everyone for your responses.

(If I don’t buy some of the recommended products that some of you have recommended it’s because I’m beyond broke.)