92 mci 102c high beams trip breaker

gene burge · August 31, 2014, 02:46:03 AM

Gotta check out my headlights today , low beams seem to be fine but when i turn on my hi beams the breaker trips & no headlights till it resets itself , low beams will stay on indefinetly but if i want the high beams it will trip out after about 3 min , any thoughts , Thanks

gumpy · August 31, 2014, 04:57:28 AM

My MC9 did that. They had been "re-engineered" by a PO who thought they knew better how to run them on 12 volts. I rewired them back to original schematic and no more problems.

Could be a short in your dimmer switch.

Lin · August 31, 2014, 10:36:57 AM

Agreed-- Go for the simplest things first. Check the switch first. If that isn't it, look for a short in the wiring.

robertglines1 · August 31, 2014, 05:54:05 PM

or a bad breaker overheating and tripping early--been there. bob

gene burge · September 02, 2014, 02:51:02 AM

removed all headlights today to check wiring for issues behind bulbs , all looks ok but i replaced all 4 bulbs because 1 had moisture inside it & reflective surface inside another had started to flake off , still had same problem with breaker tripping out with high beams on after a few minutes so i removed breaker to swap it out with one from an unused circuit- isle lights - while tightening last screw i broke terminal off breaker , should i order 1 from mci or would a auto reset breaker from a rv brake circuit be ok , thanks for ur replies, Gene

gumpy · September 02, 2014, 05:59:57 AM

There's nothing really special about the MCI breakers, other than the shape. Any standard auto-reset breaker of appropriate size would suffice. You may have
to reroute or extend some wiring as it may not fit in the original location.

gene burge · September 17, 2014, 02:30:26 AM

ordered breaker from mci & replaced , same problem , so back to checking wiring issues . after a few days off & on reading scematic's i found a wire in battery compartment mci calls a balance wire grounded under a screw to body that should go to battery , rewired it according to scematic & bingo all is well , po must not have had high beams for years

gumpy · September 17, 2014, 04:03:25 AM

Wow! That doesn't make sense at all. That sounds like the wire that provides 12 volts to the center of the light circuit, which are wired in series on 24 volts.
When a bulb burns out, this wire comes into play to keep the remaining bulb lit. It should go to the 12v center tap on the battery. There's a relay in the circuit, also.

I'm not even sure how the low beams would work with that mod.

It sounds to me like maybe the PO may have changed your headlight wiring to run straight 12 volts. Have you changed anything else prior to this?
Are your headlights very dim now?

I think I'd be doing a bit more investigation of the wiring according to schematic because that just doesn't make any sense unless other things were modified.

gene burge · September 17, 2014, 03:25:04 PM

there are 4 circuits fed off the center battery tap , a heavy gauge wire feeds a terminal strip mounted to the side of the battery compartment with 4 studs , one was rotted / corroded so po must have thought it was a ground strip & put it under a nearby screw in chassis , i was curious about the 2 diodes that feed that circuit breaker , makes sense to me now why it showed 24 volts