Morimoto XB headlight/foglight problem

shannon · Sep 26, 2021

NueveTundra said: ↑

So I can't tell what the hell is going on from start of thread to here. Trying to fallow but its hard so sorry if any of these seem like a question that should of been answered by reading.

<QUESTION'S FOR YOU>
1.) are your Regular Head Lights "Standard Bulb" or "L.E.D"
1.5) if "L.E.D" are they just a socket replacement or does it have its own custom enclosure with its own PCV control board
2.) did your Tundra come with factory fog Lights
2.5) are these fog lights a replacement "L.E.D" Bulb OR a concealed L.E.D in it's own housing
2.8) if your Tundra had fog lights are these "L.E.D fog lights using the factory plug uncut"
3.) if going to all L.E.D on the front end did you upgrade at the same time?

when a vehicle comes stock with Standard bulbs the electrical system is built to deal with the made draw. so in altering any of it , it can cause really weird issues and gremlins that will make you want to call a priest.
The good news it's fairly easy to figure these out with the right steps.

<SOME THINGS TO KNOW FIRST>
1.) L.E.D's are Light Emitting Diodes unlike a "Standard bulb that uses the current in a controlled short to illuminate light with a shielding gas". A "L.E.D rapidly flickers at such a high rate that to the human eyes its a solid light".
2.) the measured resistance of the "Stock circuit with a Standard bulb is the final resistance that the stock system is built for" this final resistance number is the number you want to remake when retro fitting something new like L.E.D's
3.) "L.E.D's are lower amp draw than a Standard Bulb"
4.) some vehicle's electrical systems if a low amp draw is applied will not illuminate a L.E.D due to the factory system thinking a bulb is out.
5.) most of the time the stock fog lights are tied into the head light circuit ( as it is with the Tundra even though you have a separate switch for fogs the headlights are first part of the circuit. this is why they wont turn on if lights are off and auto turn off when high beams are applied
6.) stay away from cutting OEM wires or splicing with butt connectors as this can add a fraction of resistance that could cause issues with working an just adds a future failure point for later
7.) L.E.D's are directional unlike a standard bulb , meaning positive has to meet the positive side of the L.E.D and negative on negative for it to create light. A Standard Bulb doesn't need direction. (this is mentioned because some vehicle's with standard bulbs are wired backwards and will not accept a L.E.D's unless de-pined and flipped on the harness for the socket. even some times as far as one side is correct but the other is backwards)

<TROUBLE SHOOTING AND INSTALL FOR A CONVERSION>
0.) verify all light circuits work in the stock configuration this will ensure any issue ran into is on the outer part of the circuit and what's changed instead of "Chasing Rabbits"
1.) should always measure the resistance of the "stock circuit" to know your end number on low beam , high beam and fogs these values are important (for some reason if your past this no worries)
2.) verify all your new L.E.D's work by using jumper wires to jump to battery an test illumination function (verified all work, good) and take note of witch side is positive and negative on the L.E.D's
3.) check the stock harness and take note of Positive and Negative on the socket verify they are correct and make your L.E.D P&N Notes
4.) install the L.E.D's in there appropriate place
5.) use either resistor's OR more "Prefeed all ready built Decoders"
6.) remeasure the circuit resistance to verify it meets the OEM Stock Standard Bulb resistance.

<Resistor's vs Decoder's>
Resistors are used for correcting resistance in the circuit since you moved to lower amp [refer to Note "Some Things to Know First" #2 #3 #4]
this will allow your stock circuit to illuminate the L.E.D when the proper Resistance load is meant.
1.) when Installing resistors you should buy the correct corresponding socket pig tails this will keep you from cutting the OEM wires and make life easier for soldering and creating the connection.
2.) [optional] if you have proper size wire and the proper tools you can pin new connectors instead of using pre made pig tale's
3.) make sure the resistor's are installed on the positive side

Decoder's I prefer since they are not only cheap (like around $20 a pair) but they are pre built plug and play not only with correct sockets on each side, but also a weather tight enclosure that not only hold the resistors for proper resistance and has some goodies like capacitor's (by holding a reserve) to combat flicker witch is common in L.E.D conversions. (Flicker happens when the electrical system is in-between giving enough ghost amps to power the low draw L.E.D but not having enough to create complete solid light) [refer to Note "Some Things to Know First" #1] , also great for correction issue like bulb out indicators an such.
- Some decoders will come with plugs that can flipped on each end so if it doesn't work off the bat , try flipping the plugs upside down on both ends , one end and flip device , try all 8 positions.

hope this write up helps any issues you should be able to figure it out and get it working with this.
Click to expand...

Wow, that's way over my head, but thank you for your time. I assume it was written for me. I had stock headlights with plug and play morimoto fog lights. Everything worked as it should. I replaced my stock headlights with Morimoto XB headlights. Whenever I turn the headlights on the foglights go on now, I cannot turn them off with the foglight switch. I have tried resistors on the high beam and the low beam and neither position solves the problem. I have noticed that if I turn the headlights on before I start the truck the fogs don't come on. I can turn them on via the switch. Once they are on the only way to turn them off is to turn the headlights off and sometimes that doesn't work. Confusing huh?

COTundie · Sep 26, 2021

Is it possible that a previous owner has done the "fog light all the time" mod?

Tho that would have been apparent before the headlight swap, so I still dunno.

Look for something suspect with the fog relay.?

shannon · Sep 26, 2021

COTundie said: ↑

Is it possible that a previous owner has done the "fog light all the time" mod?

Tho that would have been apparent before the headlight swap, so I still dunno.

Look for something suspect with the fog relay.?
Click to expand...

No foglight mod. Works as it should with stock headlights

Blang805 · Sep 26, 2021

sam68 said: ↑

I just got the morimoto headlights and xb fogs. Headlights are amazing fog lights did not work, checked wiring it is correct passenger side worked at first then installed the drivers side now neither work! Plugged stock back in after checking all fuses and they fire right up? Sending them back
Click to expand...

So for my fogs, i had to plug it in the way it was reverse polarity. Positive from truck went to black on the fog. This was on both sides too. I installed mine earlier this month. First tested + to + and - to - and no light. Switched them and they work just fine.

Log in or Sign up

Welcome to Tundras.com!

Morimoto XB headlight/foglight problem

#31
shannon [OP] New Member

#32
COTundie Whoa Black Betty

#33
shannon [OP] New Member

#34
Blang805 New Member

Products Discussed in

Log in or Sign up

Useful Searches

Welcome to Tundras.com!

Morimoto XB headlight/foglight problem

#31 shannon [OP] New Member

#32 COTundie Whoa Black Betty

#33 shannon [OP] New Member

#34 Blang805 New Member

Products Discussed in Entire Site Forum: 2nd Gen Tundras (2007-2013)

#31
shannon [OP] New Member

#32
COTundie Whoa Black Betty

#33
shannon [OP] New Member

#34
Blang805 New Member

Products Discussed in