Voltage Meter Dropping
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New User
Joined: Jul 2010
Posts: 13
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From: Sharpsville, Pa
Voltage Meter Dropping
When I press on my brake petal, my voltage meter drops to 0. When I let off, it rises back where it should be. I know I have a short in wire #5 on the brake light switch. Does anyone know where that wire goes to so I can replace it?
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
Pin 1 is voltage for the brake light switch.
Pin 2 is goes to the brake light circuit.
Pin 3 is voltage for the PCM signal.
Pin 4 goes to the PCM. It signals the PCM to disengage the cruise control and unlock the torque converter.
Pin 5 is ground for the PCM signal.
Pins 1 and 2 make up a normally open single pole switch. When the brake pedal is pressed, the contacts close and power is sent to the brake lights.
Pin 3, 4 and 5 make a double pole switch. Normally, pin 4 is grounded via pin 5. When the brake is pressed, pin 4 gets voltage from pin 3.
Pin 2 is goes to the brake light circuit.
Pin 3 is voltage for the PCM signal.
Pin 4 goes to the PCM. It signals the PCM to disengage the cruise control and unlock the torque converter.
Pin 5 is ground for the PCM signal.
Pins 1 and 2 make up a normally open single pole switch. When the brake pedal is pressed, the contacts close and power is sent to the brake lights.
Pin 3, 4 and 5 make a double pole switch. Normally, pin 4 is grounded via pin 5. When the brake is pressed, pin 4 gets voltage from pin 3.
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
I don't see how. If you were dead shorting anything in the brake switch to ground, it would blow a fuse. In the few cases I've experienced where there has been a short to ground without blowing a fuse, it at least kills the engine.
My best guess would be a wire chafing against the brake pedal or something connected to it. Probably a power wire going to the console. I would look for a wire that is coming in contact with the brake pedal that has insulation worn off.
My best guess would be a wire chafing against the brake pedal or something connected to it. Probably a power wire going to the console. I would look for a wire that is coming in contact with the brake pedal that has insulation worn off.
Cross-Country
Joined: Jan 2022
Posts: 66
Likes: 6
From: Ranger
Pin 1 is voltage for the brake light switch.
Pin 2 is goes to the brake light circuit.
Pin 3 is voltage for the PCM signal.
Pin 4 goes to the PCM. It signals the PCM to disengage the cruise control and unlock the torque converter.
Pin 5 is ground for the PCM signal.
Pins 1 and 2 make up a normally open single pole switch. When the brake pedal is pressed, the contacts close and power is sent to the brake lights.
Pin 3, 4 and 5 make a double pole switch. Normally, pin 4 is grounded via pin 5. When the brake is pressed, pin 4 gets voltage from pin 3.
Pin 2 is goes to the brake light circuit.
Pin 3 is voltage for the PCM signal.
Pin 4 goes to the PCM. It signals the PCM to disengage the cruise control and unlock the torque converter.
Pin 5 is ground for the PCM signal.
Pins 1 and 2 make up a normally open single pole switch. When the brake pedal is pressed, the contacts close and power is sent to the brake lights.
Pin 3, 4 and 5 make a double pole switch. Normally, pin 4 is grounded via pin 5. When the brake is pressed, pin 4 gets voltage from pin 3.
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