In another thread I ask a similar question, only different.
This time I'm asking what possibly can make the motor run 180 degrees out of phase?
Everything works perfectly on the bench...used a DVM to confirm the limit switch operation. Never got an answer on the function of the glass bulb inside the motor....
Relays checked out, even swapped. Same result. Pull the lites on switch and my left closes and the right opens as it should. Turn the lites off and the left tries to open. WTF?

Its a test of will at this point... Buying a new one would be the easy way out.

Is there something else that can make the motor be 180 out? anything mechanical in the gear drives? it works and runs both directions when the headlamp is NOT secured in its frame with nothing to stop it, but it does reverse direction with the headlight switch.

 

have you tried opening the hood, turning the lights on, and manually adjusting the closed one to full open? and then shut the switch off and see if they're back in synch. the glass bulb is called a mercury switch by some, if you've disturbed it your lights will act erratically. had the same issues on my 87 , upgraded to later year lights, no more problems

 

yep...I did all the gyrations with power off/on, lites up then plug it in etc...I might get the system in "time" with the possesed headlite, then the next cycle it'll go 180 out again.

I wondered if that was a mercury switch, and it did indeed pop off the glue spot that held it, but its intact and in the same spot. I've even bent it to other angles/positions in the hope that it made a difference...nothing. I do not see any mercury inside, but I can see the contacts that appear together and it does complete the circuit...so I dunno. Why would there be a mercury switch when there are mechanical limit switches? Somehow I feel that thing is the key to this goat-rope.

 

some times you can do all the tricks and they still wont work right, thats why I replaced mine, have you done a search on here? theres some good info.

 

yessir, I have, read most all of it too.
At this point its more a matter of pride than anything else...
I went thru this mess many years ago with an early c4 and have done many c4 headlites without incident. This one is just making me nutty...I think they call it "obsessed" or is it "possesed"?

I found a good article on fiero headlite motors that describe these better than ANY corvette manuals or other tech write up. Pontiac Fieros use the same motors and relays.
The limit switches are called HTS..."high-torque-switch". The possible problems are endless, the most obvious being insufficient torque to trip the switch..

 

i read that also , then I converted to later lights, its really the best thing you could do for the problem. there's a thread on here about manually opening it, then taking it apart and pulling the black gear, rotating it 180, and reassembling it. It didnt make any sense to me and still doesnt. Another member posted in a thread who actually knew how they worked and how to make them work right. try this http://www.corvettemagazine.com/2001...asp.......this is going to sound simple, and I apoligize, but have you tried the isolation relay?

 

Yep...all the relays function fine.

Turning a gear 180......

ya know, I sat here last nite wondering IF there could be something in the mechanics of the gear drive that could cause this and I did think about the position of the metal gear mate...I;ll have to get some more coffee in me, but there is a possibility that if installed wrong the small gears lever on the rubber blocks COULD keep the armature pulling in the wrong direction when it bottoms out...If thats possible, then the HTS is being tripped on the wrong side, hence being out of phase.
Its worth trying ONE MORE TIME!

Thats about all the sanity I have left before buying later model motors and mating them to my U-frame bracket and wire harness.

Damn headlite motor is my first wife reincarnated....won't cooperate, does the opposite of what I want or need, and consumes all of my time and money....yeah, thats her.

I'll try that gear change and let you know later...I might get lucky for once.

 

the bad part about the upgrade is that you need to change the u-frame also, they are a completely different animal, the good part is that you will no longer have to wonder if the lights will work , they just work.

 

well, I tried the rotating the small gear 180 with its metal clasp that buffers the stops against the rubber blocks...did nothing.
My conclusion is that the armature is just worn out and although it is the smoothest that I have even seen with all this attention, its just too gutless to operate the HTS properly.

That or there is something going on just this side of witchcraft...
All of the parts that can be seen and inspected are ok mechanically. That leaves the windings that might be burnt or damaged somehow.

 

been looking at the FSM'electrical for my 87, have you tried swapping the relays, right for left and see what that does? other than that, call one of the venders tech line(midamerica, ecklers) theyre pretty good bout helping . the only other thing is replacement, and I'm not sure that would fix it. are the magnets still glued tight and in place, and when you reassemble the motor do you rotate it manually to make sure it moves easily?

 

Yes,
to all those things and then some...at least 7 times.

This armature is so well centered in the magnets (that are perfectly set in the housing) that the only resistance to turning comes from the contact of the brushes. You can feel the N/S pole shift with rotation. The magnets are strong and the field is also strong. Very strong as matter of fact...its nearly impossible to slide the magnet off or on the armature without it jumping to its natural position,. very difficult to hold steady where the field opposes itself.

This armature has better balance then my crankshaft. The gears were all cleaned, any nicks filed, bushings cleaned and lubed, case clean, washed and blown out with air and operated on the bench both mechanically anjd electrically with a DVM attached to prove conduction and breaker operation.
Although it generates quite a surge in ohms when the armature is spun,both pos & neg it must be too weak to pull the HTS and reset the polarity. It spins much easier than the other motor that works perfectly. The glass bulb is a breaker tripped by a build-up of resistance. It's id'd on the drawing as a breaker by its symbol.

I'm going to see if I can find another armature in a box of misc parts tomorrow and see what happens. I can;t do the upgrade right now due to a dozen other unexpected expenses (besides Corvette stuff) so I'll try to repair this POS for the time being. Its difficult for me to even comprehend the motor failure because I drive at night so rarely the last yr or two that the headlights go for weeks without being raised.. Perhaps the spray elect cleaner damaged the windings or a wire broke...I dunno.
One way or another it'll get fixed, its just darn annoying when I've done everything right and thats not good enough. and I've rebuilt these 3 wire motors a doz times in the past.

 

what wound up being my deciding factor was that these are 20 plus years old and sooner or later, they just cant be fixed nomo, wishing you luck

 

AGREED.
Thanks for your assistance.

 

the HTS does not 'change polarity', it's just an 'end switch' combo that opens the motor power circuit at 'full travel'...there are two switches in each headlite, one for 'open' and another for 'closed'...the contacts in the switches sometimes fail by 'welding' themselves together, sometimes fail by corroding (no contact/no run)...the contacts can, in some failures, be reworked with an 'ignition point file'

running the motor, when not in the lite frame, may never actuate the 'end' switches.

check if the prob is mechanical (gears) or electrical (relays/etc)...install headlite assy in vehicle...unhook battery ground cable or unplug headlite motor connector...turn the 'emergency op' **** on the motor by hand to determine 'normal' rotation for up/down...recon battery, have helper actuate headlight switch while holding your finger on the emrgency **** to check for proper op.

'best resort' is to mod the 'three wires' into 'two wire' op (check the schematic in the SM, but IIRC the mod is to bug the 'gray' and 'blue' wires together)and use a 'DPDT momentary switch/pair of breakers' to manually open/close the headlites...dump all the relays ... the end switches are no longer needed for limit service but must be continuous 'electrically' (if failed, 'jumper' the end switch wires inside the motor)...with manual control the headlites can be turned off but left 'up' at the gas pumps/convenience store/etc., reducing motor/gear wear substantially, or 'up' for wash/etc.

 

Yes, I understand the HTS function and that it is the stop switch. Polarity changes thru the relays originating in the headlight on/off switch in the cabin. My motor runs fine just plugged in, not in the horse shoe, both directions. But once installed in the frame and pushing the weight, it seems to be too weak to throw or bump the HTS and trigger shut off. It will bind up the shaft pretty tight, but for some reason the HTS will not shut it off and I DID file and clean those,,both. I also tested the HTS with a DVM and worked each with a pick..pretty easy to open the points. Oh yes, the spring is free to travel and both the compression and expansion spring (inner/out) are seated in the correct groove in the housing. The shaft moves back/forth pressing it or pulling it.

My conclusion is the armature is weak and just not capable of generating the necessary torque. It'll move the headlite but it struggles with the weight. The ONLY other thing might be the HTS contacts being too soft, and opening the wrong side prematurely...I am still baffled with the thing continuing to run 180 out of phase no matter what. Polarity is screwed up BIG time somewhere..but nothing was changed. Magnets are great, I have turned the coil every possible way to try to effect a change....nada.
ALL I did to the darn thing was wipe away excess dirty grease, spray out the armature with elect motor spray cleaner,then blow-dry, lightly lube the bearings, some white lithium on the gears and reassemble...and it hates me for that !
Its possesed. I'm convinced of that.

 

the motor can be opened (sounds as if that was already done) and the 'mica' cut down between the segments on the commutator (armature contact ring)...'cutting the mica' is an 'ol time' trick used to improve motor op, can be done with a small pointed 'weapon' such as a small screwdriver/scissors point/scratch-awl/etc...'polish' the commutator with #400 sandpaper after mica cut to remove 'goofs'

see page 404 of ''****'s automobile and gasoline engine encyclopedia'', published 1920, for instructions/illustrations on mica cutting.

 

I might try that this weekend, although the commutator was already polished to reveal new copper. I also soldered in new brushes to try to get better contact and better spring tension on the commutator since the old brushes were pretty much..gone. I even shaped the brush surface with the dremmel so it got maximum 'face' on the copper segments.

Still, doing all that does not solve the biggest problem...how the polarity is reversed and no matter what I do to it, relays, breaker switch, limit switch (HTS) or anything else it STILL remains 180 degrees out of phase. The motors will run either way with the lite on/off switch.
I'll try filing the mica down this weekend but I am not very hopeful at this point.

 

I had forgotten that i did this on my OEM 87's , its the one thing that actually made them work 'right' for a time.

 

I was able to fix mine but I did find new ones on ebay pretty reasonable. May be worth a look.

 

me, neither.

'cutting the mica' was in response to your 'weak motor' complaint, and should work for motor speed/power...but my best guess for 180* motor op is still 'a gremblim' in the elec scene...'brush' wiring inside motor worries me, sadly was last century when that game was most recently played here and C.R.S has taken control.