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Crazy 12v motor issue......

cheveslakr

cheveslakr

Veteran Member
Senior Member
Only put a few miles on this vette before I tore into it, headlight motors weren't working for whatever reason. Fast forward several years to 6 months ago and I had them on the bench and th.ey worked both directions, both motors. I still tore the gear drives apart, cleaned, lubed, and reassembled. Bench tested them again, no issues. After reassembling the buckets, setting stops, and setting the stop switches, I tested the motors in the car.....all worked. This was with a remote battery and jumper wire. Installed the wiring a few days back, hooked up power, no worky. Headlights come on, rollover switch, with opporates the headlight bucket only, does nothing. Headlights don't need to be on to activate the motors. Okay, trace the power, switch has power. Unplugged the terminals to motors, they both have power on each leg up and down per switch mode. All's good. Check continuity for grounds, all good. Take the motors out, bench test again, all good. Both motors work in each direction. WTH! Now, I switched over to continuity, and for whatever reason, I checked between the ground and each lead....I have continuity between each spade to the housing and continuity blade to blade on both motors. I'm no electrician, but that shouldn't be ... correct? I'm lost here.
 
Sounds like they’re getting enough power if there’s no binding, if for some reason they’re in a bind they won’t open/close?
 
Anyway you can check power when they’re trying to open? Might take a 2nd person to help
 
Yes, they open freely, the little transmission I cleaned, lubed and reassembled, all's free in that. It's got a little thumbwheel that's geared way down and it spins freely. I bypass the car's wiring and go straight to a battery and everything works, but the alligator clip gets warm......that's telling me there's a load, the motor's may have to come apart. There is a spec on current load and it's right about 7-8 amps, but I don't have a multimeter that reads that, so I have to go borrow one. There's a 30a breaker inline under the dash, I'm assuming that's tripping.
 
For a motor using an alligator clip (which are almost always too light for any motors of heavy draw) may not be an indication, but I'd get a DC amp clamp and see the draw on the system.

You should continuity between the blades of the motor, but check for resistance. That could yield something.

The only thing that comes to mind is the grounding. I've seen weird stuff before. Trying putting in a ground directly to the buckets and see what happens.
 
Did that with the ground. Someone suggested the fuseblock terminals, which I do have a bit of an issue with. Have some insulation or fatmat under the fuseblock and the bulkhead tabs on the engine side of the firewall wouldn't both clip, only one will. It's been suggested that the connection may be a little iffy. I know plenty of hit/miss gremlins happen with DC when a connection isn't the best. I do get full voltage to the terminals, but maybe when I put it under load the connection drops???
 
cheveslakr said:
Did that with the ground. Someone suggested the fuseblock terminals, which I do have a bit of an issue with. Have some insulation or fatmat under the fuseblock and the bulkhead tabs on the engine side of the firewall wouldn't both clip, only one will. It's been suggested that the connection may be a little iffy. I know plenty of hit/miss gremlins happen with DC when a connection isn't the best. I do get full voltage to the terminals, but maybe when I put it under load the connection drops???
Click to expand...

If the wire size has been compromised (wire not full size like it's been frayed or nicked), you will definitely have an issue.
 
Finally nailed it down, temped my old wiring harness in to see if it was a firewall bulkhead issue.....nope. Ran a dedicated ground to the battery...nope. Hotwired the switch.....yep. Even though the switch tested out, it wouldn't hold current, so dissected it, filed the points, some dialectic grease and all's good. The repop switch is $140, and I don't trust repop electrics so had to give this one another life.
 

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No, original switch. I only tested continuity, and it tested okay. It just couldn't carry the amps.
 
CRC makes a good spray electrical contact cleaner, maybe try that on your orig switches and install those instead of the repops? It also lubes the switch
 
I never bought the repop switch, since I hate repop electronics. I only priced it out after cleaning this one topically, and I almost gave up on it. The original switch, which tested okay on continuity, was the one I'm using. I never gave up on it, since I've taken apart virtually every switch on this car, cleaned, lubed, and reused. l;
 
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