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2006 Escalade AWD w/DiabloSport tuner,Jet Performance throttle body/MAF,Airaid MIT
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Discussion Starter · #1 · (Edited)
I have finally after many months of speculation and removing fuses and inspecting aftermarket equipment found the issue with my battery drain. A bad voltage rectifier in my alternator that allows the voltage from the battery to be siphoned off. For those who do not know, a rectifier uses diodes"one-way voltage valves" to turn AC voltage generated by the alternator to DC voltage. When a diode goes bad it allows AC voltage to enter the battery and affect the battery ability to charge. A bad diode also pulls voltage from the battery when the system is off.

My alternator have been having this issue for a while it seems, but I did not test the diodes until recently since my alternator is not even charging the battery at all now. The rectifier in our alternator has a total of six diodes, so the system can "limp" on the working ones until they all fail. I assume that I had a couple that was blown which allowed the battery to hold a slight charge and got worst over time as the working diodes failed. The diodes can be tested easily with a multi-meter with the diode test feature. Usually bad diodes do not allow voltage at all,allows too much voltage,and/ or allows voltage to flow in both directions. My rectifier allowed .5volts in the opposite direction, which should have been zero volts.

I ordered a new GM Bosch 160 Amp alternator, so hopefully my electrical battery drain issues will be solved for good.

So for anyone experiencing weird battery drains after the truck sits for a few days they should test the alternator for a bad rectifier.

Note: Other issues like stuck seat buttons can also cause a battery drain, but it seems that a bad alternator is one of the first things to check.

I hope this helps.

Picture of the alternator with the rear cover and voltage regulator removed. The rectifier is the black component on the lower section of the alternator housing. You can test it by placing a red meter lead on the bolt(B+) on the left side and a black lead on the metal body for ground. Reverse to test for voltage moving in the incorrect direction.
 
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Discussion Starter · #3 · (Edited)
Good place to start, that's for sure.
LOL. On any other car I would have fingered the alternator for the battery draining issue I had, but it seem that many GM threads point the finger at the BCM or other control units that cause the issue in our trucks for some reason so I just "assumed " that is was faulty interior electronics that was causing the issue.

Lesson learned.:)
 

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'05 ESV Platinum, 310,000 still looking fine, really fine!
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Congrats on finding the problem! As always, thank you for taking the time and pictures for another terrific DIY!

You should ad this to the sticky thread on the how to's above!
 

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Discussion Starter · #5 ·
Thank you.

I forgot to add that you can also check the rectifier with the alternator still on the engine block. Just removed the positive battery cable from the alternator post and the connector for the voltage regulator and use a volt meter to check the diodes by placing the leads as instructed before. The diode should allows about .5-.8 volts in the correct polarity with the positive lead on the positive post and the negative lead on the case for ground, and not allow any voltage when the leads are switched. However, some meters are very sensitive so you may get some very low voltage readings(.04-.05 etc) with the leads switched since the diodes do not prevent 100% of the voltage from becoming AC, but any reading over .4 volts is too much to be leaked.
 
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Discussion Starter · #6 ·
Alright! Installed my new alternator and the electrical system seems to be stable now. I will give an update later on to clarify if the battery draining in two days issue has been resolved.

Note: I may be incorrect about a rectifier not allowing .4 volts to pass in the opposite direction with our high-output 160 amp alternators since the diodes are wired together in the assembly which may add the voltages together when checking them together in the alternator. My new alternator reads .4 volts in the opposite direction with a diode test. My old alternator leaked a bit over .5volts, so I may only have a couple bad diodes in my old alternator that is leaking voltage. My old voltage regulator bushings looks very worn which could be an issue as well. Well anyway the new alternator is working like a charm so the charging problem is solved for sure.

Shining new alternator.
 

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Discussion Starter · #7 · (Edited)
Today my Caddy passed the battery drain test. I let it sit for 3 days without starting it or charging the battery and the engine fired right up with no issue. Therefore , the new alternator was what my truck needed.

Note: Our alternators have bridge rectifiers so my diode checking method posted earlier does not work to screen out a bad rectifier in our 160 amp alternators. One method that will work would be to check to see if any AC voltage is being fed to the battery from the alternator by using a voltage meter set to AC voltage. Place the voltmeter leads on the positive and negative battery terminals with the correct polarity, and then check the voltage reading with the engine running. There should no more than .5 AC volts passing to the battery. If so, then one of more diodes has failed in the rectifier and is allowing AC voltage into the electrical system. More than .5 volts AC can cause electric issues and prevent the battery from properly charging. AC voltage play havoc with DC electronics like control modules and batteries. Bad diodes also drain voltages from batteries while the truck sits.

Another method would be to check to see if the alternator is putting out enough DC voltage with a voltmeter. Same method as above, but set the meter to DC voltage and check to see if the voltage rises pass 13 volts with the engine running. If the battery voltage falls below 12.6 with the engine running then the alternator is bad. Usually a voltage regulator is the cause of this issue, but a failing rectifier could also prevent enough DC voltage to be generated by the alternator to charge the battery due to too much voltage AC voltage passing through if many diodes fail in the rectifier.

A new alternator usually solved both issues since our alternator includes both the rectifier and voltage regulator as part of the unit.
 

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Discussion Starter · #8 ·
Update!

It has been three months now and the battery drain is still corrected by the new alternator. I have not driven my Caddy in a week a few times and the battery voltage only drops to about 12.3 volts when I check it with my battery tester. This is inline with my other cars that sit for while, so all is good.
 
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Discussion Starter · #10 ·
Thank you. I LOVE it when people (rare) actually put what fixed a problem
No problem. I also like it when members provide feedback to threads so that I know the outcome is an long term fix or not.
 
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I'm having the the same issue. Mine ended up having the door latch and lock actuator and the passenger side seat switch replaced. I was hoping that was the problem but it's still doing the same thing. I'll have to replace the alternator and see if that fixes it. When going to drive it back to the shop I got a message saying reduced engine power and had no power. It was still driving but not going over like 10 mph.... I'm stumped. Also when I would turn the truck off and shut the door the battery light was on and the letters for the hears were on (even with the truck off)
 

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I'm having the the same issue. Mine ended up having the door latch and lock actuator and the passenger side seat switch replaced. I was hoping that was the problem but it's still doing the same thing. I'll have to replace the alternator and see if that fixes it. When going to drive it back to the shop I got a message saying reduced engine power and had no power. It was still driving but not going over like 10 mph.... I'm stumped. Also when I would turn the truck off and shut the door the battery light was on and the letters for the hears were on (even with the truck off)
I'm having the the same issue. Mine ended up having the door latch and lock actuator and the passenger side seat switch replaced. I was hoping that was the problem but it's still doing the same thing. I'll have to replace the alternator and see if that fixes it. When going to drive it back to the shop I got a message saying reduced engine power and had no power. It was still driving but not going over like 10 mph.... I'm stumped. Also when I would turn the truck off and shut the door the battery light was on and the letters for the hears were on (even with the truck off)
ECU BROTHER. ESCALADE ISSUE. ONLY OTHER TIME I'VE SEEN THAT WAS IN MY NEW IMPALA. IT SAID THAT WHEN IT WAS OVERHEATING. BUT DEFINITELY CHECK THE ECU. I may be mistaken
 

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Discussion Starter · #13 ·
Update.

3 years later and the replacement alternator is stilling working fine. I also still have the same battery as well.
 
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ECU BROTHER. ESCALADE ISSUE. ONLY OTHER TIME I'VE SEEN THAT WAS IN MY NEW IMPALA. IT SAID THAT WHEN IT WAS OVERHEATING. BUT DEFINITELY CHECK THE ECU. I may be mistaken
That was for Saul86. But God damn, thank you for still being in the thread😂 I'm actually having the problem your truck did. I seem to only find 160amp for 2007 and up. Where do you suggest. I've went from oriellys to car quest and all over. For the 03-06 I see a consistent 145amp selection. There's a 150amp, a 250amp and Napa has a self branded 220amp. Also ebay has an array of crazyness.
 

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That was for Saul86. But God damn, thank you for still being in the thread😂 I'm actually having the problem your truck did. I seem to only find 160amp for 2007 and up. Where do you suggest. I've went from oriellys to car quest and all over. For the 03-06 I see a consistent 145amp selection. There's a 150amp, a 250amp and Napa has a self branded 220amp. Also ebay has an array of crazyness.
Thank you for your time. It means a lot.
 

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Update.

3 years later and the replacement alternator is stilling working fine. I also still have the same battery as well.
That was for Saul86. But God damn, thank you for still being in the thread😂 I'm actually having the problem your truck did. I seem to only find 160amp for 2007 and up. Where do you suggest. I've went from oriellys to car quest and all over. For the 03-06 I see a consistent 145amp selection. There's a 150amp, a 250amp and Napa has a self branded 220amp. Also ebay has an array of crazyness.
 

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Discussion Starter · #17 ·
I bought mine off Ebay I think or Amazon; not sure. But it is a 160A AC Delco alternator. Do a search for a 2005-2006 Escalade since they only come with 160A alternators. A search that includes 2003-2004 models will give mixed results that include the 145A versions.

 

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I have finally after many months of speculation and removing fuses and inspecting aftermarket equipment found the issue with my battery drain. A bad voltage rectifier in my alternator that allows the voltage from the battery to be siphoned off. For those who do not know, a rectifier uses diodes"one-way voltage valves" to turn AC voltage generated by the alternator to DC voltage. When a diode goes bad it allows AC voltage to enter the battery and affect the battery ability to charge. A bad diode also pulls voltage from the battery when the system is off.

My alternator have been having this issue for a while it seems, but I did not test the diodes until recently since my alternator is not even charging the battery at all now. The rectifier in our alternator has a total of six diodes, so the system can "limp" on the working ones until they all fail. I assume that I had a couple that was blown which allowed the battery to hold a slight charge and got worst over time as the working diodes failed. The diodes can be tested easily with a multi-meter with the diode test feature. Usually bad diodes do not allow voltage at all,allows too much voltage,and/ or allows voltage to flow in both directions. My rectifier allowed .5volts in the opposite direction, which should have been zero volts.

I ordered a new GM Bosch 160 Amp alternator, so hopefully my electrical battery drain issues will be solved for good.

So for anyone experiencing weird battery drains after the truck sits for a few days they should test the alternator for a bad rectifier.

Note: Other issues like stuck seat buttons can also cause a battery drain, but it seems that a bad alternator is one of the first things to check.

I hope this helps.

Picture of the alternator with the rear cover and voltage regulator removed. The rectifier is the black component on the lower section of the alternator housing. You can test it by placing a red meter lead on the bolt(B+) on the left side and a black lead on the metal body for ground. Reverse to test for voltage moving in the incorrect direction.
well I'm selling my cadillac ext 2003. im tired of dealing with this battery issue. it's more than just alternator...smh. so anyone interested hit me up!
 
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