Bronco Forum - Full Size Ford Bronco Forum banner

Ground/battery/alternator Problem?

463 Views 4 Replies 2 Participants Last post by  broncofox
Hey guys! im still abit new on finding the small tips and tricks for the bronco, but i need some help, i noticed that the lights in the cab/main and all around when the truck is on they pulsate on a high rate, i got my friends dad to check and he said its a ground.
Well maybe its the alternator ? cause i turned on the truck and unpluged the battery and it dipped abit but ran fine, but as soon as i put the high beams on it struggled at first until it idled back up.
Battery could be too since they put a cheapo battery on it so i wouldnt be surprised if that was it.

But let me know what could be the most probable cause?

also what would be the main ground pieces i should look,to make sure its working? thanks :)
1 - 3 of 5 Posts
Yo broncofox,
I assume dome, instrument panel etc lightingus the issue
Voltage is applied at all times through Fuse 8 to the Main Light Switch, Door Jamb Switches, Glove Compartment Lamp, Map Lamps, and the Cargo Lamp.

When the Main Light Switch is turned fully counterclockwise, or if the left or right doors are opened, the Dome Lamp is energized and lights up.

The Map Lamps are energized independently of the Dome Lamp by two switches one located at each Map Lamp housing.

Headlight Switch Switch Fires, Part Number SW-2103: "...Over the past two years, this office has experienced fires caused by another potential problem in Ford vehicles. The problem exists within the dimmer portion of the headlight switch in Ford vehicles. The light switch involved is a Model SW-2103. These are the pull out type headlight switches usually located in the lower left corner of the front dash of Ford vehicles. The headlight portion of the switch has two pullout positions, the first for parking lights only, and fully out for headlights and parking lights. The shaft of this pull-out light switch can be turned clockwise and counterclockwise which activates a dimmer switch, lowering and raising the intensity of the lighting in the instrument panels respectively. Fully rotating the shaft counterclockwise past a notch activates the interior lights within the vehicles. The potential problem exists within the dimmer portion of this switch. The dimmer mechanism consists of a metallic resistive coil set inside a ceramic disc positioned over the shaft of the switch. The coil is exposed on its front side away from the passenger compartment. The front side of the coil passes across a contact permitting a current to flow through a certain portion of the coil when the switch is pulled our in its first or second positions. The greater amount of coil through which the current is permitted to pass (clockwise most position) creates the greatest resistance and therefore dims the dash lighting to its lowest intensity. The opposite position provides greatest intensity. Through our investigations, we have found that the coil can fail owing to wear and/or possible material defects or damage. A fractured coil can maneuver itself free of the ceramic disc permitting it to come in contact with the metal bracket which mounts and grounds the switch to the vehicle. When this occurs, a current can flow through a portion of the coil creating high temperatures melting the metal material of the coil and possibly igniting surrounding combustibles. This mechanism has been observed in three separate incidents by this office. Two of these resulted in a fire. The mechanism is precipitated by wear and/or defect in the coil mechanism. If the former is true, we expect there will be an increase in fires caused through this mechanism given an increase in service time. To this date the problem appears to be somewhat limited. However, this particular light switch has been utilized in numerous Ford vehicles. Therefore, a small increase in failure rate owing to age and wear could result in a significant increase in fire losses. The SW-2103 Light Switch Assembly discussed above is reportedly installed in the following Ford vehicles: 1986 -1997 F100, F150, F300; 1990-1994 Explorer; 1987-1994 Ranger; 1987-1990 Bronco II; 1992-1997 Aerostar..." Miesk5 NOTE: No Bronco Listed, but this may be the result of typos or incomplete research by the company.
View attachment 170346 View attachment 170347

G201 Location pic in a 92 driver kick panel); is for all the windows, courtesy lights, instrument cluster, lighter sockets, blower, & horn switch. Instead of many wires at the ring like I was remembering, they spliced them together in the harness that year..."
View attachment 170348
Source: by BeastBronk at FSB
So i should switch it to relay and/or buy a new headlight switch? since it says the main cause of fires and damage are from the switches them selfs

i didnt even know there was a ground there!!! ill check that out
Inspect the switch, it may have even replaced by a previous owner, shop or Ford dealership.

Switch Knob Removal; Insert hooked tool into knob slot to depress spring, then pull off shaft.
ok ill check it out
1 - 3 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.