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OK Folks,

Time to bug you all with a very specific problem.  I searched the forum and could not find info on the vehicle/problem specific enough to give me a direction.

The car is a 1995 Fleetwood Brougham.

Ever since I have owned it (9 years) it has had a problem I just worked around, by driving it at least once a week.

The dreaded "Parasitic Power Drain".

Yeah, been dodging that one.  Best fix known to man - drive it.  But this week the battery went dead in 4 days.  I have seen signs of fluctuation in severity and have been generally observing it all this time and poking around here and there.  I didn't get lucky in those efforts.

So today I opted to actually do a voltage drop test at the fuse box before getting more involved with relays, actual amperage draw testing etc.  (Who wants to reset all the radio stations?)

So... As a reference I chose the CCM Bat feed as a baseline measurement (inferred acceptability).  At the fuse, it fluctuated between pulling .6 mA and 1 mA.  I went with 1 mA and after referencing this table: fuse-charts.pdf (powerprobetek.com I see this translates to a draw of 135 mA. (inferred acceptability)

With that in mind I went through all the fuses.  A few were pulling some current. All of the problem candidates are listed below. (read from right to left maybe)  I think you will agree one circuit stands out.  Power Locks.

mA Result    Circuit    Fuse Amperage    Milli Volt measured
1713           PWR Lock        20                              5.5
135            CCM bat           10                               1
127             RAP Bat            25                             0.3
93              Park lts             20                             0.3
11               HVAC Bat         10                              0.6
27              Tail lts               10                              0.2
212            Wiper                25                              0.5
            
2318    Total drain        

So, my question:

Have any of you folks, especially the long time Caddy techs, seen this and might you be able to tell me where to go, other than to h***.  LOL.

I know I have to get into the weeds on this.  I m just hoping for some direction to start with.  The locks all function as designed.  There is no obvious problem.  I am not in the mode to tear into all the doors but may do so eventually because I want to get inside the RR door anyway.  

Meanwhile, I am pulling the power lock fuse to see what that buys me.  I don't think I need to get into testing amperage draw while pulling fuses.  Unless one of you tells me different, I think I have my culprit.

Thanks in advance for any ideas and if you want to shoot me for asking this question, please do.  It will save me some work.

RC 

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I just went out to pull that fuse but decided to do a Bad Alternator Diode Test first.

I'm assuming you may know what that consists of.  Easy stuff.

My smallest AC scale on my DMM is 200V.

I should see no more than .5 AC voltage at the battery.  (black on black, red on red).

My meter displayed 31.2 volts!  I don't know if I can believe it.  I see none of the usual signs of this problem like fluctuation lights, etc.

Any thoughts on this would be appreciated.

I have not pulled the power lock fuse yet because now it's guilt is in doubt.

Thanks!

RC

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If the battery goes dead after 4 days of inactivity, the alternator, although it may not be performing to spec, is a separate issue.

The door locks may be an issue if one of the lock actuators is not completing its lock/unlock and is still trying?

I recall having a similar sticking seat issue where the power seat was basically stuck trying to move & soaking up power.

Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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Long shot here but can you confirm your meter has a good battery. When mine have a low battery it will read high voltage like that

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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@ Bruce - Yeah, I'm thinking 2 separate problems here.  I want to double down on the alternator test before going that route.  Those things are expensive!  (figures)

@ Rockfangd - Good thought.  It hadn't occurred to me.  I will put a new battery in it tomorrow and give it another shot.  Part of that double down thing I mentioned. 🙂

Does anyone know which particular service manual I want to track down for the power locks?  Looking for electrical specs so when I get into the doors I know what the solenoids should test at.  I think this is going to be a case of pulling it in the garage and opening up all four doors so I can isolate one at a time if necessary.  Have to see what is going on in the RR door with the window regulator anyway.  The window has lost it's ability to stay level.  lol.

I will report back on the alternator test tomorrow.

Thanks guys.

RC

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The Helm shop manual is the one to have for maintaining your Cadillac.  Watch ebay or other used sources that may offer at a discount, but also know what they are new for comparison.  I have seen used shop manuals offered for more than new prices.

Bruce

2016 Cadillac ATS-V gray/black; 2013 Cadillac ATS 2L Turbo Premium (Wife's)

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Got it.  Thanks Bruce.  I will look that up and shop around.

So, I put a new battery in the DMM as Rockfangd suggested and redid the diode test.  Good call Rockfangd!  It read 8.2 AC volts across the battery. 

Reading up on the ramifications of that and it seems clear to me the first step needs to be a new alternator.  Showing that AC voltage (more than .5V) indicates a blown diode in the alternator.  When the car is running it just results in dirty power.  But when it is shut off, the blown diode will allow current to backfeed throughout the car wherever it can go.  Last night a neighbor came over and we were hanging out in the garage.  The Caddy was outside with the hood up.  After about 10 minutes the under hood light turned off.  As it should.  But after 30 seconds or so, it came back on.  Rinse and repeat.  Totally made me more suspicious of the alternator theory and the retest today nailed it.  Obviously all kinds of circuits are getting wake up calls when the accessory power is supposed to be off.

So I can't trust the results of any of the circuits the voltage drop test pointed to.  If the problem persists after the alternator replacement I will revisit that and hopefully I will have landed that manual Bruce mentioned, by then.

I know some of you guys don't need all these details but I put them here for others that may be searching for the same problem one day.  Sorry.  🙂

And besides.  I have been driving and repairing cars for a long time now and this the first time I have seen a bad alternator function for at least 5 years.  It was about that time when I had another situation where I had to rely on that 10 minute accessory power cut off (a whole 'nother saga involving the security system and a body shop that was sloppy) so I know for a certainty it is supposed to go dark after 10 minutes with the key off.  Not go dark and then come back alive like I saw last night.

Thanks guys.  I will drop a note here when I have the alternator in place and report if it was the fix.  Again, for reference for the readers out there.  Hope so at 300 bucks! AC Delco.  It is on order and will be here on 5/4.  I'd rather drop 300 bucks than tear into the doors anyway!  Fingers crossed.

RC

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Sometimes the alternator will be slightly warm when that type of failure has occurred. Glad to hear you are on the right track

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Actually yes!  It was warm.  I noticed it the other day.  Man, if only all this knowledge could be put in one place...  Wait...  Can you say CaddyInfo.com?

Seriously, there is so much value to this site.  I try to respond to queries when I can but I only do so when I know it is correct and not some assumption that I dreamed up because I may have lucked my way through a problem.

Thanks,

RC

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Honestly. In todays day and age so many people are quick to judge based on what they read or hear, But suggestions and replies are a huge help to others. Even if it is not correct it can still help. Sometimes members can be 1000 miles away. Without seeing the car in person things can get difficult.

This forum is full of strong members. Any suggestions are highly appreciated

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Hi guys sorry for not noticing this post before tonight.

I have the unique privilege of having built a custom Art car from a retired police car.

The B -Body and G body are essentially the same chassis with and extra 10inches of length added behind the drivers seat.

I used a complete harness and all amenities from the Fleetwood in the Caprice.

So I have run through the entire harness and merged.

That power drain of 5mA is the delayed accessory buss controller pull the module and check again.

However it never caused a battery drop below 11 volts for me so I always started. I was using a Optima Red that is kind of like a battery backup battery in it's discharge curve.

If you had 8VAC on the battery during running there was probably a drain through the same bad diode module not measured.

The cop cars came with a larger 138A alternator and a different drivers side bracket to support the big alternator with the heated front windshield option for the L91 caprice this bracket and alternator can be had from dealer as recent as monday a week ago. It uses a longer belt as well I installed one on my suburban.

Also that noise in the AC is called slugging I worked for PRO at that time and we had hundreds of complaints but just replaced the compressors during the warranty rather than issue a bulletin. What the issue is , there are two versions of the R4/R11 compressor the R11 has about 50% more displacement but physically the same size. The larger evaporator on the Fleetwood and second Rear AC on  Escalade and Suburban causes liquid to be present on the suction side of the compressor when using a R4 in place of an R11. Hense slugging and compressor failure. 

If you have the noise then you have a couple of options On g-Body you can swap out the evaporator with a B-body on the GMT400 Escalade and Suburban they went to a Sankyo compressor in 1996 junk yarding can find the complete bracket set , hoses and pulleys for about $150 the Compressor for 60 on amazon

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You are correct about the compressors. Simple term is like hydro locking the compressor. Nearly every GM compressor I have seen fail was because of that. Either burns out  the clutch from over working it, or wrecks the the compressor internally and distributes through the system.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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OK.  Alternator is in the car.

.04 VAC shows at the battery when idling.  Within spec and far less than the 8.2VAC the old alternator showed.

I also checked for current on the power lock circuit doing the voltage drop test as before.  0 mV.

My fuzzy radio is also cured.  I had attributed that to the power antenna, possible a problem with the antenna lead(s).  Just never found a reasonably priced antenna or anything else wrong.  Been that way since 2015.  lol.

So.  Time will tell but I believe my problem is solved.  Still cannot believe it was the alternator all this time.  smh.  Now I have to let it sit for a week or so and see if it cranks.

Thanks All, for your input.

RC

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