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BRD

1990 Buick Reatta “Cycling” Parasitic Draw Challenge

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Posted (edited)

Have a good battery and alternator on my 1990 Buick Reatta coupe that I have now owned for 30 years.  But recently discovered a draw on my car battery that has it fully discharging overnight.  Unable to figure out what might be causing this and greatly appreciate any insight you can provide.

 

Testing conditions:  1.) Car engine off, doors shut, key removed from ignition exactly in “off position,”  2.)  Battery fully charged (12.6v) but not yet fully completed circuit to car for power (i.e. negative terminal removed and battery/power has not been restored to car since battery fully died),  3.)  All connections appear to be solid “i.e. no loose wires,”  4.) Positive battery terminal connected to positive car battery cable,  5.) Negative battery terminal running through multimeter (negative battery post > multimeter > car negative battery connecting cable), 6.)  Multimeter set to 10A reading amperage. 

 

Then connect circuit (via multimeter) and get approximately:

 

6.96 amps for 67 seconds

3.44 amps for 43 seconds

0.06 amps for 10 seconds

3.44 amps for 34 seconds

0.06 amps for 10 seconds

3.36 amps for 35 seconds

0.06 amps for 10 seconds...

 

Amperage then cycles like this for at least seven minutes (and presumably longer) until the battery dies.  Pulled each known fuse and relay during subsequent tests and nothing changes (i.e. no dramatic drop back down to 0.06 when pulling the "shorted fuse"/circuit).  On another of the three tests the draw basically cycled from ~3.6 amps to 0.06 amps every 60 or 30 seconds. 

 

Have a five minute video of multimeter amperage reading to see this battery draw in real-time, if viewing would help.  Cropped to just multimeter display - as in png file below - to make a very small file size.  [But I'm not aware how to attach mp4 video files in this forum, or if possible). 

 

Any idea as to what might be causing this draw that now drains my battery overnight?

 

Thanks!

 

BRD

 

1990 Buick Reatta Coupe

 

Reatta Battery Draw.png

Edited by BRD

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The blower motor control modules have been known to cause some weird problems when they fail including killing the battery even when the key is off. I think it would be a good idea to unplug the electrical connectors to the module and run your tests again to see if that might be your problem. Do you hear any clicking when the cycling is going on?

 

blower control module.png

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Tis indeed strange. Trying to imagine what has a 3+ amp draw and the cycling is baffling. Not enough draw to be tripping a breaker so looking at items that are hot without ignition under normal conditions. Trunk and courtesy lights of course, lighter socket, head and tailights and the power antenna possibly. The blower module as mentioned has caused many dead batteries but both blower module and antenna usually are audibly running? Pass key system tripping and recycling? Sorta spitballing here.

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Ronnie, Thanks for taking the time to look at this and posting the blower control module photo.  The car is completely silent when running these tests – so no clicking noise.  I will unplug the electrical connectors, as you suggested, and let you know if I can provide any additional details.  Best regards, BRD

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2Seater, Thanks for taking the time to look at this and giving some ideas.  I will recheck the items you mentioned to see if I can notice anything out of the ordinary.  The car is completely silent while it is drawing these ~3.5 amps.  Will let you know if I find out more. Best regards, BRD

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I disconnected the electrical connectors to the blower module and re-ran the tests with connectors attached and unattached.  Unfortunately, still got the exact same result:

 

0.06 amps for 29 seconds

3.44 amps for 23 seconds

0.06 amps for 29 seconds

3.44 amps for 23 seconds

0.06 amps for 29 seconds

3.44 amps for 23 seconds…

 

Given that this amperage draw is so precise and happening on an exact interval, would that lend itself to something being commanded by a computerized component?  (I.e. a “regular” shorted wire would not go “off” and “on” every 29 seconds and then stay “shorted” for 23 seconds before repeating indefinitely until the battery runs dead).

 

I re-pulled common fuses for radio, body, lighter, AC, HVAC, etc. but got same cycling amperage.

 

Some additional background:  This problem seemed to appear after my ac hose assembly was replaced and freon recharged by a radiator specialist.  I had not used my car (much) or air conditioning (at all) since it was replaced.  Found out today when driving the car that the mid-level fans are not blowing any air.  But cold air is coming from dash vents.  I did not, however find any blown fuses for ac components – unless they are located somewhere I did not inspect.  Could this be related?  Also had my oil pan replaced by another garage with the oil level sensor reattached.

 

Some other items that could have an electrical system impact:

 

1.  The actuators for the door locks stick.  I have to manually slide the locks up and down to fully seat in the proper position (“up” and “down”).  I ran the amperage test with doors fully locked and with original remote key locking the doors properly.  Also ran the test with doors unlocked.  Same results.

2.  My display always indicates “Lights On” even when lights are not on.  Day and night.  Has done this for at least last 10 years.  But never seemed to have any impact on battery.  I replaced dash display a while back and pulled headlight switch to check pins.  One receptacle appears to be burned but it might have always looked that way (photo attached).  Not sure if this is related to “Lights On” always on. 

3.  The small orange square light on the upper left corner of the headlight switch is always on day and night, even when car is locked, engine off.  For last 30 years.  (Is this normal?)  Photo attached.

4.  Car alarm system hasn’t worked for at least the last 15 years.

5.  Cruise control works off and on for last 20 years.

6.  The “Break” and “ABS” lights are on (I personally replaced Teves accumulator ball 10 years ago and probably have to replace it again.  Was something like $90 on Amazon but probably costs a small fortune today).

 

But again, these things have happened for years with no noticeable impact on my battery, as is the case today, (draining from full charge to dead overnight).  I do not think they have anything to do with this “current” situation (pun intended) but wanted to put these out there, in case there is some connection.

 

Finally, while inspecting my battery and the nearby connections, I noticed a small metal box between the battery tray and the coolant overflow tank.  I cleaned it up a bit and put back.  Doesn’t seem to connect to anything.  What is this for?

 

Greatly appreciate your thoughts and insight!

 

BRD

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All that is a lot to digest all at once. Sorry I can't answer a lot of your questions about your '90 because there are lots of differences between it and my '88. 

 

I think I would try to isolate the circuit that is causing the cycling by disconnecting all the fusible links from the terminal block (shown in the photo below) and see if the cycling goes away. If it does start attaching each fusible link one at at time until you see the cycling start. Then you can trace that circuit to see what is powered by it that might cause the cycling.

 

This is just a shot in the dark... The only thing I can think of that goes through a cycle and cuts off when the ignition is turned off is the headlight door control module. When the module tries to operate the door motors, the motors are powered on and run until the module senses a high current indicating the doors are closed and it turns the motors off. If the high current isn't sensed by the module in a certain period of time, as in the case of a defective headlight motor gearbox,  it will timeout and turn the motors off. Since you say you are getting a continuous light indicating the lights are on it might be possible that your module is repeatedly going through a cycle where it is either trying to open or close the headlight doors. All this is just speculation but it might be worth investigating if you can't find any other cause for the cycling.

 

Other than the unusual light indicating the light are on, are you having any problems with the headlights or headlight doors? I see a burned terminal on the green connector indicating something is wrong. I think that connector needs to be replaced even if it's not causing your current problem.

 

ground_junction_block-1.jpg

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I agree with Ronnie that the plug needs to be replaced. That could be the source of your problem. Something is triggering the "lights on" in your dash and the little light being "on" in the switch tells us that is what is happening. 

 That bad spot on your connector could one day short the rest of the way and cause the switch to get burned up [1990 switches are one year only Reatta only and are expensive to replace] or the wiring behind the switch [not as likely].

 I would start there.

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I think Dave is on the money. My car has a replacement headlight switch courtesy of him, but the initial cause in my case was higher wattage headlight bulbs. The behavior of the lights was very unpredictable when damaged. I believe the headlight door module has a time out feature as well as the normal load sensing so possibly there is some form of connection to the indicator light at the switch? Your car may benefit from the headlight relay harness to take the switch load. You mentioned the a/c components. Is it possible the compressor is trying to cycle the clutch due to a pinched or damaged connector?

 

That little box does not belong to any component I know of on a '90 and doesn't exist on mine. It looks like the outer case for a circuit breaker, which would make me wonder what it was for originally? 

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Posted (edited)

Gentlemen,  Thanks for the time and recommendations.  Will try disconnecting all the fusible links, as Ronnie suggests.  However, before I do that, I think you might also be on to something about the headlight doors.

 

As I imagine with almost all Reatta owners, I have had multiple challenges with the headlights not working properly.  Have replaced headlight motors and gears at least three times over past 30 years.  Interior headlights switch replaced at least twice.  Along with digital instrument cluster at least three times.

 

Current headlight drama is that the right headlight will not go up when I push the headlight switch, every 15-30 cycles.  (I.e. it works perfectly for 15-30 on/offs but then it will not go up).  To fix the problem, I have to get out of car and turn the right headlight manual knob exactly six turns counter clock-wise, then press the interior lights switch/button and it works every time.  Will then last for 15-30 more cycles before having to manually rotate the headlight motor knob.  Has been doing this for the past three years.

 

Two weeks ago, I was driving the vehicle during the day and pressed the headlight switch and neither of the lights came up.  Tried a few more times and nothing happened.  When I arrived home 10 minutes later, I tried the lights again, when the car was parked, with the engine running, and lights came right up with no problem.  Tried three more times and they worked perfectly.  Took the car out last night and lights/headlight doors worked perfectly.

 

I have been using Sylvania SilverStar  H6054ST headlights for past 10 years.  As you know, they work much better than stock.  But mine also seem to burn out every 4-6 months.  Along with one of my 14 taillights failing every 2-3 months.  I am open to HID or LED lights at some point but still not a fan of the cooler tones.

 

Appreciate your advice on these questions:

 

1.  How do I access/troubleshoot/replace the “headlight door module”?  Is this the same as the headlight control module?

 

2.  Is it also possible that a faulty headlight relay is causing this amperage draw?

 

3.  Where can I find or how can I replace/repair the green headlight switch connector with the single burned terminal?

 

4.  How can I install a headlight relay harness?  This is my only vehicle and I frequently drive it long distances and coast-to-coast.  Could use the extra power going to my headlamps.  I saw multiple posts about this in the forums but could not locate a “recommended” consensus on relay method/kit for a 1990 Reatta.         

 

Thanks and best regards,

 

BRD

Edited by BRD

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1 hour ago, BRD said:

1.  How do I access/troubleshoot/replace the “headlight door module”?  Is this the same as the headlight control module?

I think we are talking about the same module. Maybe my terminology isn't correct. I'm talking about the module that controls the headlight door motors. I don't know how to troubleshoot the module but in your case unplugging it will tell you if it's causing the cycling problem. I believe the module is located under the hood on the drivers side under the fuse box.

 

2.  Is it also possible that a faulty headlight relay is causing this amperage draw?

Maybe but I doubt it's causing the cycling.

 

3.  Where can I find or how can I replace/repair the green headlight switch connector with the single burned terminal?

I think you will have to cut off the connector and splice in a good used one. Jim Finn will probably have one and he might be able to tell you the best way to install it.

 

4.  How can I install a headlight relay harness?  This is my only vehicle and I frequently drive it long distances and coast-to-coast.  Could use the extra power going to my headlamps.  I saw multiple posts about this in the forums but could not locate a “recommended” consensus on relay method/kit for a 1990 Reatta.

I wouldn't change any of that until you've fixed the current problem you are having. No need to further complicate things.       

 

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I have not tried removing a terminal from a connector like the headlight switch, but it should be possible with a thin probe designed to access the release pin, maybe an eyeglass screwdriver? From the relationship of the plug and switch, there may be a spare terminal to relocate as a replacement. Failing that, splicing in a new harness end is the best choice. 

The headlight door module is indeed under the relay box and window wash tank at the drivers front of the engine compartment. Might be able to access the plug pulling the washer fluid tank but I don't remember the exact way it is oriented.
Perhaps I should have suggested the headlight harness as a future upgrade after this problem is solved. No need to introduce another variable for sure. 

 

I would believe anything similar to a relay or other actually moving part or contact would make a sound. That said, when I acquired hearing aids almost two years ago, I found sounds I didn't know existed. I think even a free decibel meter app for your phone may hear things below the audible. 

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Thanks Ronnie and 2seater.  I will look into removing the headlight control module for the amperage testing and let you know if I have any progress.  If that's not the problem, will investigate the fusible links as recommended earlier.  Best regards, BRD

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I have both an extra headlight module and headlight connectors available. I just use solderless connectors which I think are fine as the headlight lead is in a protected area where moisture is not an issue.

 While it may seem like a good idea to cut all the wires at once, don't. Do them one at a time. It makes matching wires up easier and you won't blow any fuses and complicate things any more. [Yes I have experience at cutting all the wires at once].

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Thanks Dave – will keep that in mind as I continue to troubleshoot the issue.  Will be in touch regarding the parts as I assess the situation.  Best regards, BRD 

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Update: I think I’ve isolated the parasitic draw as coming from the headlight door module, as per your recommendations. [Thank you!]  Was not easy getting to the module, as I don’t have proper tools and basically just started taking everything apart.  But once there I disconnected the two sets of wires plugged into the “box.” One with orange/yellow wires and the other with green/white wires. [Photo attached]

 

Then ran tests with fully charged battery, engine off, keys not in ignition, etc. and here’s what happened:

 

1.  With orange and green sets of wires disconnected:  Multimeter consistently displayed 0.06 amps for at least five minutes.

2.  Connected the green set of wires:  Multimeter initially displayed 3.44 amps for a few seconds but then dropped to 0.06 amps and consistently remained there for at least 10 minutes.

3.  Connected the green and orange set of wires:  Multimeter remained steady at 0.06 amps and remained there for at least 15 minutes.

 

Put everything back together and ran car last night to cycle lights/headlight doors. Checked battery this morning.  Holding at 12.2 volts.  Recently, it would have dropped down to around 1.4 volts overnight.  I will continue to monitor battery without running engine or connecting trickle-charger and see if it continues to hold at/around 12+ volts.  This “reset” did not stop the constant “Lights On” indicator lights from remaining on.  Again, these indicators have been on for at least 10 years so I am not sure they are related. 

 

Appreciate your thoughts on following questions:

 

1.  Do you think the “computer” associated with the headlight door module simply reset when I disconnected these wires (with power to the module) and the problem is possibly “permanently” fixed?

 

2.  I can visually trace the green wires as assigned to the lights/headlight doors.  What do the orange/yellow wires connect to?  (When these are connected, I hear a temporary clicking noise in engine compartment when connecting my car battery)

 

3.  Do you think that my right headlight door remaining shut every 15-30 cycles has/had anything to do with this headlight door module issue?

 

4.  What is the appropriate continuous amperage draw for a 1990 Reatta coupe when engine/accessories not running?

 

Thanks and best regards,

 

BRD

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I'm glad to hear that you are making progress but I'm afraid you aren't out of the woods yet. 

 

Now, here is more speculation on my part because I don't know for sure how the module is programmed to operate. 
It is my gut feeling that you reset the headlight module when you unplugged the headlight switch or when the battery was disconnected if you did that. There is an input [yellow wire] on the module that gets a signal from the headlight switch telling it the headlights are on.  Since the light on your headlight switch that indicates the lights are on is continuously burning, I'll bet the module is getting a signal that the headlights are on as well.  Each time the input gets a signal from the headlight switch activates the module to operate the headlight door motors to open the doors.  I think the module getting an indication that the lights are on my be triggering the module to go through a cycle that checks to see if the headlight doors are in the proper position or something. I really don't know. I do believe it's possible the wire going from the headlight switch to the module being hot all the time might have caused the terminal in the headlight switch connector to overheat. Did you notice what color the wire was that goes to the overheated terminal?

 

If it were me I wouldn't trust the car until you have changed the bad connector and resolved the problem with the "lights on" indicator being on all the time. Even if the battery drain goes away and everything continues to work fine there is always the chance the overheated terminal will get worse and possibly cause a fire.

 

2 hours ago, BRD said:

1.  Do you think the “computer” associated with the headlight door module simply reset when I disconnected these wires (with power to the module) and the problem is possibly “permanently” fixed?

See above.

 

2.  I can visually trace the green wires as assigned to the lights/headlight doors.  What do the orange/yellow wires connect to?  (When these are connected, I hear a temporary clicking noise in engine compartment when connecting my car battery)

Orange and orange/black wires go to headlight door fuses to supply power to the headlight module and door motors on my '88. Not sure but I would expect them to be the same on you '90. The click occurs on my car too. I had always wondered what caused it an now I know.

 

3.  Do you think that my right headlight door remaining shut every 15-30 cycles has/had anything to do with this headlight door module issue?

Don't know but I doubt it. I would check that out after you resolve the battery drain issue.

 

4.  What is the appropriate continuous amperage draw for a 1990 Reatta coupe when engine/accessories not running?

This pretty much covers everything I know about battery drain. I think it should apply to your '90 but I don't know for sure.  How To Measure Battery Drain

 

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Yes, mine makes a click in that same area when connecting the battery. I wonder of the cyclic nature of the one headlight motor is caused by a bad spot in the motor armature? Maybe the up down cycle stops in a slightly different place and eventually hits the dead zone?

 

Did that indicator light go out when the module was disconnected? Just speculating maybe the reverse is true, the module is backfeeding somehow and indicating lights on? I honestly don't know, but I do know that it is very sensitive to the grounding through the lights and I have had the headlight door try to bite me when I had a bulb connection issue at the plug after changing a bulb.

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Posted (edited)

I just tried to get a baseline amperage draw on my 90 and the results are sort of inconclusive, or I have a meter issue? I connected my multimeter through the disconnected negative battery terminal and I one heard the click but the meter registers nothing. Subsequent tries elicited no click, but the display does show movement of the decimal point so something happens?? Maybe I blew the internal fuse?? In any case, I grabbed a small analog 3amp gauge and tried it inline with the ground and it does make the click, registering on the high side of 3A for less than a minute when it dropped back to barely registering on the meter. This is not a precision instrument but it does move the needle a bit when connecting after the timeout so there is a tiny bit of current flowing. No cyclic draw was noted for five minutes.

 

EDIT: I did indeed have a blown fuse and the meter worked as designed on a second test. I get an initial current of 3.32A which drops shortly and holds at 3.19A for the allotted time, at which point I get .019-.020A right on that balance point. One caveat that may cause the exact draw to be different is my radio is non functional at this time. The fuses are good so it may be a connection at the aftermarket Pioneer radio that I disturbed when I had the HVAC control panel out for cleaning?

Edited by 2seater

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Posted (edited)

Thanks for information Ronnie and 2seater.  Thanks for taking the time to check the constant amperage on your 1990, 2seater. 

 

Ronnie,  I agree with you that the burned out terminal is very likely a problem/hot connection and needs fixed.  Probably one of – if not the – root of the problem.  Maybe another is my (3rd!) faulty headlight motor.  I’m also curious if either of you have the small orange square light always on?  Is it supposed to do that?  Seems like a minimal power draw and maybe a feature so you can find the light switch in the dark?

 

2seater, I did not check (but should have) to see if the “Lights On” indicator goes out when I disconnect the yellow/orange wires.  Will do this on my next test.

 

2seater, I had a very similar multimeter reading on mine yesterday with the initial 3.4 amp that then went down to 0.06 amps (and stayed there unlike before when it would enter the “problem” cycle).

I checked the battery voltage again just now.  Is at 11.01 volts.  Down from 12.2 volts this morning.  I did not use my car today and will check again in the morning to see if it drops much further.   I know its basically a math equation to calculate how long/much a 0.06 amp draw will take to drain the battery.

 

I used to have a really good DieHard Platinum battery and never had (or was not aware of) these electrical problems.  Maybe the power/quality of that battery masked these electrical problems for several years?  Will address the battery in another post (pun intended).  Once all these electrical issues are resolved (there are many more), I will also likely invest in another high quality/power battery.  Current battery in car is a Champion 30 month with 800+ cranking amps (700 CCA), exactly one year old.

 

Ronnie, I was not able to find any photos of the wires going into the connector.  Should have taken those as well.  Next time I open dash panel I will check.

 

When troubleshooting the headlight door module, I discovered another problem.  The “fuel tank vapor” hose (1) going to my Fuel Vapor Canister Solenoid (2) was not connected.  I have no idea how long this has been disconnected.  I connected it again (see photos).  But reminded me of a number of problems I have had for last 5+ years smelling fuel and rough idle.  Maybe this was the/a cause?

When I take everything apart again, I am interested in getting a new Fuel Vapor Canister assembly.  Read that not having this work properly can saturate the filter and render it useless.  I will start a new post about this.

 

Also, when troubleshooting headlight door module, I found the wiper fluid pump, which has not worked for 5+ years.  I would like to replace this too when taking everything apart again.  With air filter assembly and hose removed (to access headlight door module), will also take out and clean IAC, as I understand this can cause a rough idle and other issues, as I currently experience. 

 

It’s probably becoming obvious that my only car and daily driver of 30 years has a lot of problems.  There are many other issues that I have not addressed in this “amperage” post but will in others for easier subject reference by members with similar problems.  So I am trying to fix as many as possible while I have access to basic tools and a place to keep my car inside when performing work [this is not normally the case].  This is why I asked about the headlight relay harness earlier.    

 

Is it possible to know exactly what function that burned-out forth pin on the green-plastic light switch connector does?  I.e. some schematic somewhere that says “the fourth pin provides indication to module that lights are on”?  Would be nice to figure this out first and make sure, before I cut and splice in a new set of wires/ports to the connector.  Or is it possible to surgically repair the single faulty pin/receptacle without removing everything else?  Also, is it possible that a fault in the headlight door module or a short somewhere else is causing the burned out connector?  In other words, if I "fix/replace" the burned out green connector, will it just burn out again because of a fault elsewhere?  I.e. is the burned out pin a symptom and not the cause of the problem?

 

Greatly appreciate your thoughts and advice!

 

BRD

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Edited by BRD

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