Headlamp wiring connector overheating

[ascdds]

The Deutsch diode receptacle for my headlamps (located in the electrical bay outside below the driver's window) is overheating. You can see by the photos how it melted. I replaced the diode receptacle and female but it is still overheating when both headlamps are plugged in and turned on. If only one headlamp is plugged in and turned on it will not overheat, only when both are plugged in. The 2 15A auto resetting fuses do not get hot, only the diode. Any help would be appreciated.

[MrMark52]

If fuses or breakers aren’t tripping it tells me that there is a high resistance in the connector. Bad crimps are typically the cause although it can also be the connections within what the connector is hooked to.

As an example - the plastic connector that holds the wires into the back of the dash air blower speed switch for our dash A/C and Heat is all melted. Looking at the plug and the switch it connects to - it’s obvious the switch was failing due to its poor design (the contact tabs are held to the back of the switch by rivets that loosen over time and use due to resistance in the connections).
The heat created across the joint was such that whatever 2 metallic connections in the assembly were in use would get hot enough to melt the plastic yet not blow the fuse.

[TB673]

Just a thought...
I know on SOME newer vehicles, as delivered from the manufacturer, the Low Beams and the High Beams will never be illuminated together (as was the practice years ago in the old Sealed Beam era).
I have seen modifications to have the Low Beams to stay on when the High Beams are on.
If this modification was made on to your rig, this could explain the high heat generated at the connector.


Or if the headlamp bulbs were upgraded to a higher wattage bulbs (if the lamps are halogen).



Tim

[bigb56]

Originally Posted by TB673

Just a thought...
I know on SOME newer vehicles, as delivered from the manufacturer, the Low Beams and the High Beams will never be illuminated together (as was the practice years ago in the old Sealed Beam era).
I have seen modifications to have the Low Beams to stay on when the High Beams are on.
If this modification was made on to your rig, this could explain the high heat generated at the connector.


Tim

This can also happen when people re-lamp with high wattage lamps without upgrading the wiring and socket (porcelain). In fact, I will say that this is the most common cause of melted connectors.

[MrMark52]

Originally Posted by ascdds

The Deutsch diode receptacle for my headlamps (located in the electrical bay outside below the driver's window) is overheating. You can see by the photos how it melted. I replaced the diode receptacle and female but it is still overheating when both headlamps are plugged in and turned on. If only one headlamp is plugged in and turned on it will not overheat, only when both are plugged in. The 2 15A auto resetting fuses do not get hot, only the diode. Any help would be appreciated.

Are the plug and receptacle shown in your first post for a single lamp? Or are both lamps wired together in a harness where all the current of both lamps go through that connector?

If all the current for both lamps go through that one connector - I would be suspect of either the headlamps have been upgraded without consideration of the wiring and associated connectors, or poor wiring terminations.
Bottom line, and the point of my previous post is - melted plastic, whether it’s the insulation or the terminal receptacle or plug is not always evidenced by a blown fuse or tripped relay (12 volts across 1 ohm of resistance is the same as a 12 watt light bulb of heat concentrated within the plug, aka 42 btu).

[ascdds]

Originally Posted by TB673

Just a thought...
I know on SOME newer vehicles, as delivered from the manufacturer, the Low Beams and the High Beams will never be illuminated together (as was the practice years ago in the old Sealed Beam era).
I have seen modifications to have the Low Beams to stay on when the High Beams are on.
If this modification was made on to your rig, this could explain the high heat generated at the connector.


Or if the headlamp bulbs were upgraded to a higher wattage bulbs (if the lamps are halogen).



Tim

There was a recall about 3 or 4 years ago and I do believe that they modified it so that the low beams would stay on when the high beams are on. However, the connector heats up even if the high beams are off and I can't understand why it would take 3 or 4 years for the modification to cause a problem. Also, the headlamp bulbs are original and have not been changed.

[ascdds]

Originally Posted by MrMark52

Are the plug and receptacle shown in your first post for a single lamp? Or are both lamps wired together in a harness where all the current of both lamps go through that connector?

If all the current for both lamps go through that one connector - I would be suspect of either the headlamps have been upgraded without consideration of the wiring and associated connectors, or poor wiring terminations.
Bottom line, and the point of my previous post is - melted plastic, whether it’s the insulation or the terminal receptacle or plug is not always evidenced by a blown fuse or tripped relay (12 volts across 1 ohm of resistance is the same as a 12 watt light bulb of heat concentrated within the plug, aka 42 btu).

Both lamps are wired together in a harness and all current of both lamps go through that connector. However, the headlamps and wiring have not been upgraded or changed in any way.

[MrMark52]

The last post in this thread may be of interest to you (in fact, all of the posts in the thread help in determining the final outcome) - https://www.irv2.com/forums/f103/hea...wn-494295.html

It sure sounds like the problem your having.