Welcome to the Cadillac XLR Forums!

Help! Voltage fluctuation 2004 XLR

CW928

Member
Joined
Mar 16, 2020
Messages
21
Location
Maryland
My XLR/V(s)
2004 XLR
Good afternoon. Starting about 3 months ago, on occasion, the voltage dial would go way down and back up as the car picks up speed and other times it works perfectly and on some occasions the faulty voltage indicator would show up and the battery gets drained, the battery is new. If I turn the car off and restart it, it is usually okay for that trip and may or may not happen for a time or two, any ideas, alternator malfunctioning or some other electrical part? My number is 443-223-6840 if you would prefer to call or text. Any advice is very much appreciated, thanks!
 

richardyoo

Seasoned Member
Joined
Jan 1, 2009
Messages
340
Location
Houston, TX
My XLR/V(s)
2006 Silver XLR-V
in the XLR its actually a generator, not an alternator... I don't quite understand the difference myself, but two things worth noting in the XLR Generator is that 1) its water cooled... and 2) its variable output and its controlled by the engine computer... from those two things we can presume that its expensive to replace - both in terms of cost of the part, and the labor to replace it.... so I hope you don't have to go through that hassle.

I think the first step is to hook up a Tech2 scan tool and watch the generator status and see what the engine computer is commanding and what is resulting from that both in terms of voltage output and error codes. Then you can make an educated guess to determine what the next step is.
 

mickeytee

Seasoned Member
Joined
Apr 5, 2017
Messages
773
Location
North Atlanta
well you can get a lot of arguments out of the generator/alternator name. The alternator contains a generator inside of it on most new cars. old generators made enough voltage to run a car with no battery. In the old days we could take one good battery and start 4 or 5 off road trucks and drive them all day with no battery if we did not shut them off. You cannot do that today. 1/2 the sites call the xlr an alternator 1/2 say generator. Its basically both as a computer uses the voltage it makes all the time to recharge the battery and run all the accessories. and adjusts output as needed.. Just call it an alternator and you wont get funny looks at the service center. . Take a voltage meter and check your battery with the car off .12.9-13 volts and check it running. it should be 13.5 to 14 . check all the connections to the battery and the engine ground wires. To change on out is a lot of work. requires holding the engine up with a hoist and dropping the front crossmember . I have done it without but its easier and faster to jack up the car .block the engine , and frame drop the crossmember a little. then lower the frame a little dealers going to charge 6-8 hours I would think plus the alternator is fairly expensive at 3-500 depending on the source.
 

richardyoo

Seasoned Member
Joined
Jan 1, 2009
Messages
340
Location
Houston, TX
My XLR/V(s)
2006 Silver XLR-V
Ya... what mickeytee said.. lol 😂

 

CW928

Member
Joined
Mar 16, 2020
Messages
21
Location
Maryland
My XLR/V(s)
2004 XLR
in the XLR its actually a generator, not an alternator... I don't quite understand the difference myself, but two things worth noting in the XLR Generator is that 1) its water cooled... and 2) its variable output and its controlled by the engine computer... from those two things we can presume that its expensive to replace - both in terms of cost of the part, and the labor to replace it.... so I hope you don't have to go through that hassle.

I think the first step is to hook up a Tech2 scan tool and watch the generator status and see what the engine computer is commanding and what is resulting from that both in terms of voltage output and error codes. Then you can make an educated guess to determine what the next step is.
Hi Ricardo, this is great info, thank you very much, I will track down a Tech 2 scanner. Have a great Friday and weekend.
 

Cadillac XLR Forums

Not a member?  Join now!  It's Free!

Learn more about Supporting Membership

Supporting Vendors

Taput Tunning LLC

Top Hydraulics

Cadillac XLR Registry

Click here to enter the official Cadillac XLR and XLR-V Registry
Top Bottom