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BRD

1990 Buick Reatta “Cycling” Parasitic Draw Challenge

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All good questions but I have few answers. You have such long term ownership likely have seen more than most. I have had mine 27 years but has been summer only and only 85k miles in that time, so many problems have never cropped up for me. Our own Daves89 has more miles under all conditions than I could imagine.

 

The vapor canister hose is a common problem. It seems it was a bit short from the factory. It purges itself through a port upstream of the throttle body so it does not draw actual manifold vacuum and probably doesn't do anything relative to the idle. As for the canister being ruined by not being regularly purged, I do not know. I do not have a canister on my car as it was removed for routing intercooler piping and has no affect on how my car operates.

 

I just have a two year old mid-grade battery from Advance Auto Parts and battery drain has never been an issue for me. I have let my car sit for more than two weeks without issue starting it after that time. Now this is summer only and my car is always garaged, so temperature swings are reduced. I don't do anything special and I have watched with interest the few people that report battery drain issues but I just haven't had the problem and have little to contribute. I do think that the .06A (60ma) draw is too high and something is still not right. 

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2seater answered most of your questions as well or better than I could have about the purge canister. 

 

11 hours ago, BRD said:

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?

The FSM does show a layout of the headlight connector and each pin in it, but it doesn't specify what each pin actually does as you describe. What is does show is the color of each wire going to each terminal in the connector so with a little bit of research in the FSM you could  trace down where a wire goes.  Keep in mind that a wire color may go to a lot of different places/devices. There are a lot of splices under the carpet beneath the seats where the wires branch out and run all over the car. The splices are notorious for giving problems due to corrosion if they are exposed to water. That might be the source of a lot of the electrical problem you are having, especially if your car sits outside. This will tell you about it: Wire Splice Repair

 

Those connector pinouts are shown at the end of section 8A of the '88 and '89 service manual. Probably in the same section of the FSM for a '90 but the connector and pins will be different from the early model cars because the headlight switches are completely different  If you have a '90 model FSM you could find the wire color of the burned terminal in you headlight connector and see if it goes to the headlight module. If you don't have a service manual for your car you should get one. It makes troubleshooting these cars a lot easier.

 

 

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I will look in my 90 manual and see if I can enlighten. I second Ronnie's conjecture about the splices under the seats. I will say this; just because the carpeting feels dry is not a reliable indicator of the condition under the carpet and padding. The water may actually be pooled underneath and you not know it. Seemingly unrelated items were cured on my car by repairing the splices under the seats, primarily the drivers seat in my case. Items include: the inner turn signal bulb on both rear lights, the power trunk release on the fob or rear key, the drivers door courtesy lights and the lock/unlock with the shifter. I think there were others but don't come to mind. 

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This may help a little. I don't know if this is early or late production (with the extra relay), but two quick snaps of the early wiring diagram. I have others I took but my phone decided they need to be sideways🙃 The indicator light in the switch is not for locating the switch, it is the actual lights on indicator.

 

 

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2seater, could you get a shot of the headlight switch and the headlight door module similar to the one below. It's on page 8A-102 in my FSM.

 

Your previous photos shows the yellow wire from the "headlight on" indicator lamp going to the BCM. I'm wondering if the yellow wire also goes to the headlight door module like it does on earlier models.

 

Screenshot_2020-06-26 89Reatta-42-8A-ElectricalDiagnosis pdf.png

 

 

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I will see what I can find. I am pretty certain you are correct about the yellow wire as I am almost sure that is the wire I cut and repurposed when I did my homemade headlight relay upgrade. 

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Ronnie and 2seater:  Thank you so much for the response and images.  I was able to locate a 1990 Buick Service Manual but not entirely sure how to find/interpret the information.  Here are some pages that I am looking over now.  Not sure if my 1990 coupe is considered "late" or "early" model, so I included both.  

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This what I found as well as instructions for disassembly of the wiring plug. The weatherpack picks are just flat, narrow probes, like an eyeglass screwdriver with the flat tip extended toward the handle about an inch🙄  I  may have miscounted but it looked like there was a spare unused terminal in one of the headlight sockets which might be relocated to repair the one terminal. The burned plastic should have nothing to do with the terminal contact as long as it will seat firmly.

 

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My 90 was early production and the only difference in the headlight wiring is a relay was added between the headlight switch and the headlights which effectively takes the headlight load off of the switch. The added relay didn't really have a home so it was taped or wire tied to the large wiring harness inside the console of the passengers side forward of the fuse panel. Last four digits of my vin is 0145

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Looks like the '88-'89 and '90-'91 cars are about the same in the way they are wired to activate the headlight doors but I can see there are some differences. I hope there isn't enough differences that some of the things I've said in this thread weren't correct. My comments were based on my assumption that all the Reattas are pretty much the same in that respect.

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17 minutes ago, Ronnie said:

Looks like the '88-'89 and '90-'91 cars are about the same in the way they are wired to activate the headlight doors but I can see there are some differences. I hope there isn't enough differences that some of the things I've said in this thread weren't wrong based on my assumption that all the Reattas are pretty much the same in that respect.

I think your advice has been sound and now that BRD has a manual, it should make life easier. Pretty hard to copy or follow the path from a bunch of small glimpses. I do think it is possible there are some differences in the headlight door module but I am not at all certain. I remember when I was going through my own headlight travails, pretty much a problem of my own creation, Dave gave me a couple of modules to test, but I don't remember what they were from, although I think it was from another GM with pop-up headlights and they did not work on mine, but dim memory that they did work on an 89. I shouldn't even bring it up, because it may be misleading.

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4 hours ago, BRD said:

Not sure if my 1990 coupe is considered "late" or "early" model, so I included both.  

Look for the lone relay tied up beside the fuse box shown in the photo below. If you have it then you have a late model '90 with the updated headlight wiring designed to take the load of the headlights off the headlight switch.

 

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2seater and Ronnie:  Thanks for the information.  I just took some pictures of the fuse box and what might be the "late model" relay (from behind the panel wall) you showed in your last photo.  I need to get in there and deep clean!  The fuse box is definitely upside down.  Based on this, it would seem that my car is a "late model" 1990?   

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Based on the wire colors going to the relay in the photo below it appears you do have the later model with the headlight relay. That is good because it should take a lot of the load of the headlight switch. As far as I know all the '90 models had the fuse box turned upside down. That is because the same box was used in '88-'89 models. It was just mounted on the passenger side of the console behind the carpeted side panel and it was mounted upright.  

 

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Thanks for the clarification.  Trying to take all of the recommendations and now figure out how to further troubleshoot/repair (i.e. a sequential plan of action).  Please feel free to correct or add to my understanding that the problem is likely in one of these components:

 

1.  Headlight Switch Assembly

2.  Headlight Switch Connector (with single burned terminal)

3.  Wiring (a short)

4.  Headlight Door Module

5.  Headlight Door Module connector

6.  Headlight Motor

 

Current anomalies to this specific issue are:

 

1.  Had a parasitic draw of ~3.44 amps that cycles on and off. (This seemed to go away when I disconnected the Headlight Door Module connectors but might return at any time if left unresolved)

 

2.  Have a 0.06 amp constant draw that might be higher than usual for a 1990 “late model” coupe.  Did not run my car for last 48 hours and battery has drained approximately 2.33v over that time (from 12.60 to 10.27v).  So ~0.05 volts battery charge lost per hour.  Maybe this is now normal?

 

3.  The small orange “Lights” indicator light is always on (at least last 20+ years)

 

4.  My “Lights On” is always lit on my digital display (at least last 20+ years)

 

5.  One of the terminals on the light switch connector is burned (maybe fully functional but just showing wear from being connected to a wire that has been on constantly for 20+ years?)

 

6.  Right headlight door “sticks” every 15-30 cycles until I manually rotate the headlight motor knob 6 times counter-clockwise and then cycle lights off/on from inside the cabin.

 

Greatly appreciate your thoughts on how to proceed!

 

BRD

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48 minutes ago, BRD said:

1.  Headlight Switch Assembly

2.  Headlight Switch Connector (with single burned terminal)

3.  Wiring (a short)

4.  Headlight Door Module

5.  Headlight Door Module connector

6.  Headlight Motor

I think my first step would be to unplug the headlight door module and see if the "lights on" indicator on the headlight switch and IPC goes out. That would tell you if an unusual feedback from the module is keeping the indicators on. I don't think that is happening but I would eliminate that possibility before moving on. While you have the module disconnected test again and see if the 0.60 battery drain goes down any. Next I would fix that overheated terminal in the connector or splice in a new connector...

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Thanks Ronnie!  Will try this tomorrow.  Will also take the dash panel off to inspect the wiring going into the burned light switch connector.  To clarify, do you mean unplug the two sets of wires going into the headlight door module (green and orange sets like I did last time)?  Or do you mean to actually unplug/remove the entire headlight door module itself?  

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Just unplug the connectors going to the module like you did before and see if that makes the indicator light on the headlight switch go out.

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Thanks!

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Posted (edited)

What is the last four digits of vin, or date listed in door?

 

For reference, I drove to my cottage yesterday afternoon, about 50 miles and parked. Approx. 18hrs later battery voltage with a meter is 12.29. I have no other reference, like where it started, but will check again this afternoon and see what’s what.


My experience has been that feedback or odd indicators are ground issues. That said, I believe you have been through multiple switches and instrument clusters and perhaps the fault lies in the cluster? Maybe that phantom light appeared after something was replaced?

I rechecked battery voltage again which is approximately 24hrs after parked and I find 12.36 which is sort of interesting if my earlier 12.29 was correct. It would make sense if originally was 12.39 and I mistyped🙈

Edited by 2seater

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