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Headlight repair and electric diagnostic...

Schrade

Well-known member
Joined
May 2, 2009
Messages
1,315
Location
Not in CF; BANNED!!!
Corvette
'90 LT 5
The thread just went over 10,000 hits, the last 3,000 withOUT the pics (I managed to delete my pics off their servers after they banned me, and that was no easy task ;) ). Much obliged :thumb XSS is your friend!

Anyway, this is sort of what we had goin'... (sequence and text/pic syncin' might be off a little)

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Remove the entire assembly (motor separation next post, although pictured here):

Have ready a towel to put down the assembly!
Disconnect headlight power supply.
First remove the screws at the lower assembly - with yellow circle.
Then remove nuts numbered '1' - at both sides of headlight assembly.
Then loosen, BUT DO NOT COMPLETELY REMOVE, the '2' numbered nuts.
Get your free hand onto the headlight assembly, and apply pressure to keep the assembly in place. I had a boo-boo here (post 6)!!!
Then remove the two remaining nuts #2.
CAREFULLY, pull away the assembly.

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removal of motor from assembly:
loosen bolt 4, second pic
loosen bolt 2, first pic (ALSO GOOD PIC OF THIS BOLT ( in red circle) IN PIC 3)
you can then remove bolt 1 (it will not come out, until bolt '2' is loosened) and bolt 3, first pic, and the bolt shown in fourth pic, with a yellow circle, which is on the back side of the h/l motor.

then remove the roll pin in blue circle 3rd pic (and red circle first pic)
The roll pin (blue circle) was tough. I was afraid of manglin' it. I put the penetratin' lube on it, then put the vise grips on it gently and squeezed, so the pin would close a little, and allow the oil to get on the outside of the pin. Turn slowly, and work it - it is tight!!!

I didn't pull it all the way out either - above, first post, red circle.

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Motor breakdown...

Step '2' here - when you lift off the cover, watch for 2 wafer-thin brass washers post 4, 3rd pic. There's a gasket here, which I replaced with a thin film of RTV silicone.
Step '3' here - I didn't do that part...
Step '4' here - see side note; disregard reference to post 24 and 11. Use caution SLOW - the double click is the two brushes on the armature being pushed out by the TINY springs. post 4, 1st pic, shows a brush spring.
Also watch the nylon gear shaft rotate, as the worm drive/armature is removed, like your distributor from the cam drive. Remember this at re-assembly. I don't know how many teeth you can 'miss' by, with no problems.
(EDIT: watch for a lone ball bearing to drop out from the end of the worm drive, when you pull it from the armature housing - see post 5, 2nd pic, to see the ball bearing).

If you're really dedicated, and want to hear sweet music when the repaired h/l works again, do this: re-grease the washer-type ball bearing inside the armature housing. Carefully remove the manual rotation knob from the shaft, and slowly remove the armature winding/shaft from the housing. Buried in there is the washer-bearing, and a few washers. See post 6 pic and not 'reeding', which holds knob onto shaft.

Continue steps 5 -12; see additional posts and pics for reference/tips. Step 7 here - the shaft is a very tight fit into the nylon gear with the new delrins. I just used hand pressure, no carving.

You'll have to do the fishing line trick to hold the brushes back in - pic 3, and 4, here.

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More breakdown/re-assembly...
pic 3; a slight tap with the screwdriver handle will separate the nylon gear from the shaft.

C23FA840C2A549509F09D8A101BC8940.jpg
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At re-assembly, watch the lone ball bearing...

Put a dab of grease on the end of the drive, to hold the ball in place...

1CA1BF8AB3D548EB97C228D1AF495242.jpg


B701B401690B40ACB0CD05D2CB8564BC.jpg


and remember to turn back the nylon gear from its removed position - it got pulled back by the worm drive, like your distributor off the cam drive.

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What a pain re-editing. (I think I'd rather get a wrench-on ;LOL )
 
More pics...
 
...and a few more... The string-and-brush trick, and grease to hold the armature solo ball bearing into place ;) ...
 
AND, in case the headlights are reversed when you re-assemble: (READ CAREFULLY, AND NOTE!!!)

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No turn at all? Pics edited in to go with text... Don't connect stuff yet - just lay it out, so you can see what you're doin'.

Note - there is a mistake in the FSM wiring diagram: Headlight motor wires are green and grey for both left and right headlight motors.

2hlschem.jpg


1hlschem.jpg


Now again, note the wiring diagram labels of the wires that go to the 2 motors - A, B, C, and D. NOTE them for the procedure, and when a reference is made to them, change accordingly.

Disconnect lefthand (or righthand, if it is broken) headlamp door 2 way connector. Notice the gray and green wire on the end of the connector that are the headlight motor wires.

hpim0721.jpg


hpim0717.jpg


hpim0719.jpg


hpim0720.jpg


Connect the piece of wire on the 12V (+) FUSED (see what I wrote on the schematic about 'fused testing' above) jumper to the GREEN WIRE connector pin. Connect the wire on the (-) cable to the grey pin connector.

hpim0722.jpg
 
NO laughing at my Mickey Mouse multi-meter nuh uh!!! :mad

To test the module ground wire, you need a multimeter. Put the (+) mm probe on the battery (+). Unplug the headlight module connector that feeds the harness (both are circled; one of the connectors has a black wire which is the ground wire, and should be connected to the ground on the rail underneath the headlight). Put the mm (-) probe to the black pin in the connector, the same way you did with the other procedure. The mm should show 12V (about).

If it does not show 12V, you have a broken ground wire. If it DOES show 12V, the module is bad.

hpim0723.jpg




hpim0724.jpg


hpim0726.jpg
 
Could you please send me the wiring diagram for the headlight power? Section 8-A is missing from my manual. My headlights flip up but do not light up. I'm thinking its the headlight switch in the dash? Please send it to steve.lehigh@juno.com

Thanks!
 

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