coolnesss Posted July 25, 2009 Report Share Posted July 25, 2009 Last night my 2002 ETC started running badly, and I got all sorts of idiot lights on the dash lighting up. I found that the negative battery cable was loose. After a jumpstart, it turned out that the alternator was fried. Two months ago, a dealer replaced the oxygen sensor - and I'd like to know if removing the negative cable is part of that procedure, so I can talk with them about it. Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 25, 2009 Report Share Posted July 25, 2009 Last night my 2002 ETC started running badly, and I got all sorts of idiot lights on the dash lighting up. I found that the negative battery cable was loose. After a jumpstart, it turned out that the alternator was fried. Two months ago, a dealer replaced the oxygen sensor - and I'd like to know if removing the negative cable is part of that procedure, so I can talk with them about it. Well maybe and maybe not. I would say however no, there is no need to disconnect the battery to change an O2 sensor with the key off. For the record however, its possible that the jumpstart fried your alternator and its also possible that the alternator just died from the heat, heat is very hard on an alternator, that is why they water cooled it at one point. Its also possible that the loose negative cable increased the resistance, but I think you would have starting problems long before you would damage the alternator. Its probably just coincidental that you found the loose battery connection, your alternator probably just crapped out.. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
coolnesss Posted July 25, 2009 Author Report Share Posted July 25, 2009 Well, I know they did disconnect at least the positive cable because the clock was off-time when I got it back. The car has 32k miles, so I think that it's unlikely the alternator just fried itself at that mileage. Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 25, 2009 Report Share Posted July 25, 2009 Well, I know they did disconnect at least the positive cable because the clock was off-time when I got it back. The car has 32k miles, so I think that it's unlikely the alternator just fried itself at that mileage. Well if that is the case, you NEVER disconnect the positive cable to do maintenance, if you need to disconnect the battery, you always disconnect the negative cable, its safer to you personally, you can get hurt (burned from rings, etc) badly disconnecting the positive cable grounding out to the frame... So you are correct, THEY probably disconnected the negative cable and did not tighten it, to spec Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
KHE Posted July 26, 2009 Report Share Posted July 26, 2009 Disconnecting the negative battery cable is not part of the procedure for removing the oxygen sensor but it sounds like the dealer removed the cable for some reason. The voltage regulator and/or diode trio in the alternator were damaged due to the loose connection. A very easy repair for an alternator rebuilder. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 26, 2009 Report Share Posted July 26, 2009 Disconnecting the negative battery cable is not part of the procedure for removing the oxygen sensor but it sounds like the dealer removed the cable for some reason. The voltage regulator and/or diode trio in the alternator were damaged due to the loose connection. A very easy repair for an alternator rebuilder. Kevin, do you think they disconnected the battery to delete the code (the lazy method of getting rid of the code). Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
KHE Posted July 26, 2009 Report Share Posted July 26, 2009 Disconnecting the negative battery cable is not part of the procedure for removing the oxygen sensor but it sounds like the dealer removed the cable for some reason. The voltage regulator and/or diode trio in the alternator were damaged due to the loose connection. A very easy repair for an alternator rebuilder. Kevin, do you think they disconnected the battery to delete the code (the lazy method of getting rid of the code). No idea. But I do know that a loose battery connection will fry the voltage regulator and/or diode trio every time. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
coolnesss Posted July 26, 2009 Author Report Share Posted July 26, 2009 They had to replace the oxygen sensor to smog it - and I had to leave it there overnight so they could drive it enough miles after the check engine light was out to be able to smog it. Thanks guys, I appreciate the consult! Link to comment Share on other sites More sharing options...
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