Lighting question
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New User
Joined: Mar 2014
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From: Johnson City NY
Lighting question
1996 F-Superduty (F-450) w/ 7.3 Turbo - after driving at night time, turn off head lights, body lights stay on... Is that the headlight switch malfunction, or some thing else??? I can turn off the body lights by disconnecting the batteries... Weird... I have never seen this before....
Lead Driver
Joined: Oct 2003
Posts: 8,476
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From: Madison, WI
Disconnect the switch. If the parking lights go off, switch is faulty. If they still don't go off, there's a short/sneak circuit going on somewhere.
When you reconnect the batteries, do the parking lights stay off or do they come back on?
When you reconnect the batteries, do the parking lights stay off or do they come back on?
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
Hmm, that usually suggests a relay getting stuck closed, resetting when power is completely removed. But neither the parking lights nor the headlights have relays in the circuits, not in the pickups anyway. F-SD might be wired differently. Are there any aftermarket lights wired into the parking lights? Commercial bed with side/perimiter lights?
Fleet Mechanic
Joined: Oct 2006
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From: Spokane, WA
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New User
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From: Johnson City NY
Yes, the wrecker body has 3 "MARKER" lights on each side, and then on the lower tail board 4 brake / marker lights, 2 aft tail lights, and 2 more s/t/t in the light bar - best I can tell was wired correctly, not too long ago we rewired the truck body, and even then was having the same issue, but wasn't being problematic, like now killing the batteries if left unattended....
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Thread Starter
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New User
Joined: Mar 2014
Posts: 14
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From: Johnson City NY
K... Will try, need to get hands on some tools, and get to the switch, as far as relays - none installed, upgraded 6 of the lights to LED, rest are 1157 or 1156 bulbs
Postmaster
Joined: Sep 2007
Posts: 4,195
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From: Medford Oregon
No, it's not hijacked, we are asking each other questions to help resolve the issue.
Which 6 did you upgrade to LED style? Brakes you can't do LED's unless they have the associated load resistors due to a PCM pull up resistor. This would cause all kinds of lighting issues.
Which 6 did you upgrade to LED style? Brakes you can't do LED's unless they have the associated load resistors due to a PCM pull up resistor. This would cause all kinds of lighting issues.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
LEDs won't cause any lighting issues. The light switching is purely electromechanical; the PCM does NOT control the lighting. The only PCM-related effect of using LED brake lights is that the PCM can mis-interpret the load, and "think" that you're pressing the brake pedal when you're actually not (for example, when you hit one of the turn signals), and will interrupt the cruise control and will unlock the torque converter on automatic transmission trucks. Moreover, the PCM isn't tied to the parking light circuit at all; it can't magically turn on or keep on any exterior lights.
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New User
Joined: Mar 2014
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From: Johnson City NY
HAD 6 of these - 3 on each side 2 amber & 1 red
REPLACED THE BEE HIVE WITH THESE LED Lights
ON AFT ( OR UPPER SIDE REAR ) ARE OEM Jeep TAIL LIGHTS with 1157 - LEFT them alone, just made sure where hooked up right
AND then from the light bar - REPLACED the OLD BEAT UP DOT LIGHT STRIP CLUSTER TO LED, and installed new guts in the 1157 bulb sockets in the light bar...
HAVE NOT BEEN ABLE TO TEST LIGHT SWITCH, BEEN BUSY TODAY...
Postmaster
Joined: Sep 2007
Posts: 4,195
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From: Medford Oregon
LEDs won't cause any lighting issues. The light switching is purely electromechanical; the PCM does NOT control the lighting. The only PCM-related effect of using LED brake lights is that the PCM can mis-interpret the load, and "think" that you're pressing the brake pedal when you're actually not (for example, when you hit one of the turn signals), and will interrupt the cruise control and will unlock the torque converter on automatic transmission trucks. Moreover, the PCM isn't tied to the parking light circuit at all; it can't magically turn on or keep on any exterior lights.