Acura MDX SUV Forums banner

21 - 34 of 34 Posts

·
Registered
Joined
·
558 Posts
The connection between the brake lights and the cruise control is unclear. By using LEDs the current consumption was reduced - no "bleeding off" of excess. What can be said with some confidence is that the addition of the correct size resistors would return the electrical consumption to the same level as the incandescent bulbs, and the circuit should operate as previously. The problem with using LEDs in some automotive applications is that there are sensor circuits that flag burned-out lamps by observing a reduction in current; since LEDs use less current they trigger the sensors. More commonly, and with the MDX, the current is used to make a flasher relay work, and a change in current changes the rate of flashing (hyper-flashing). The fix is the same: add resistance so the total is the same as previously. Other cars still use socketed flasher relays, which can be replaced with relays that are not current-dependent for the switching (they have a timing circuit inside). Unfortunately the MDX still uses the current for flashing but it is built-in and can't be replaced - hence the resistors.
 

·
Registered
Joined
·
573 Posts
Discussion Starter #22
The problem with using LEDs in some automotive applications is that there are sensor circuits that flag burned-out lamps by observing a reduction in current; since LEDs use less current they trigger the sensors.
This is what I was curious about specific to the MDX, as this is basically the "CANBUS" system that some cars use to light up an indicator light/message on the instrument cluster to alert you to a bulb being burnt out. It would appear the MDX does not make use of this, at least as it pertains to the rear brake, turn signal and reverse lights, is that correct?
 

·
Registered
Joined
·
136 Posts
Thanks PDS, I ended up replacing the back up lights today, super easy with the sylvania's. I think I'll wait on the brake lights and turn lights bcs they look really good and they all match in brightness and I don't have to do any research (lol). Good advice thanks for doing the research. I usually replace all the lights on my vehicles with LEDs but I got stumped on my Navigator; which the MDX replaced and am wary of going through the hassle again.

Just today I noticed my LED fog lights on my 2010 accord (my commuter car) started flickering (they are about 5yrs JDM H11s). So looks like i'm going to have to replace them now. LED's are usually much better and for head lights and fog lights they can't be beat. But for signals and brake lights (excluding the high center brake light), I can take them or leave them. Just haven't had good experience with them.
 

·
Registered
Joined
·
32 Posts
Still debating on whether to replace my brake lights and rear signals with led bulbs, mostly because of the resistor part. If anyone completes the install and has pics to share that may be of some help, I would appreciate it!
 

·
Registered
Joined
·
573 Posts
Discussion Starter #26
Still debating on whether to replace my brake lights and rear signals with led bulbs, mostly because of the resistor part. If anyone completes the install and has pics to share that may be of some help, I would appreciate it!
Only thing to note is that the resistor only applies to the turn signals. You can swap just the brake lights and not have to worry about the resistor.
 

·
Registered
Joined
·
32 Posts
Only thing to note is that the resistor only applies to the turn signals. You can swap just the brake lights and not have to worry about the resistor.
Correct, but I would want the brake lights and signals to have the same look and brightness (my OCD kicking in). So, it’s an ‘all or none’ type of thing for me
 

·
Registered
Joined
·
573 Posts
Discussion Starter #28
The resistors do not need to be mounted on metal - they have their own heat sink fins.

I just did a search for "LED T5" on Amazon and found this: https://www.amazon.com/WLJH-Extremely-Dashboard-Instrument-Indicators/dp/B0798R76CR/ref=sr_1_8 A little more searching would probably find smaller quantities. FWIW I don't think you'll really notice if you don't replace these.
When you installed the resistors do you recall whether the blinker socket has 2 or 3 wires?

Also now that I think about it the resistor shouldn't get that hot as it only has current going through it for minutes at a time only when using blinkers as otherwise there's no current going to the blinkers so double sided tape is probably fine

Sent from my SM-G975U using Tapatalk
 

·
Registered
Joined
·
558 Posts
I'm confused - you are quoting me about the glove box/console lights, but asking about the flashers?

The only lights that need resistors are the four flashers, or turn signal, lights. The rear lamps are basic single filament, and aftermarket LED bulbs should just work, or possibly rotated 180°. The cable to the lamp is 2-conductor, and the resistor is connected between the two conductors.

The front amber flashing bulb has two filaments: one is always on (parking lights) and the other is the flasher/turn signal. There are 3 conductors: a 12V+ for each filament, and a common (12V-) for both. The resistor is connected between the flasher filament 12V+ and the ground (common, 12V-). All T10 sockets have a provision for 4 contacts; single filament bulbs either have 2 contacts or 4, with opposing sides the same. Two filament bulbs have 3 unique contacts, with the 4th either unused or duplicating ground IIRC.

In their wisdom (?) Acura designed out the pluggable/replaceable flasher relay, and built the flasher circuit into the car's electrical system. But it appears that they kept the old (cheap) system of flashing, which IIRC uses a bi-metallic strip that turns on and off with the heating caused by the current, and is thus subject to hyper-flashing. But they do isolate the flashers on a trailer so that it doesn't cause hyper-flashing with the OEM trailer wiring kit. Why they didn't just design it with a simple timing circuit is beyond me... it would have cost pennies.

I have not owned a luxury German car, but my understanding is that they do deal with these details well. The MDX isn't really in the same category; it is somewhere above the mass market, such as the Honda Pilot, and below the luxury category. That suits me as the price is commensurate with the market position, and the MDX is quite satisfying to me, if imperfect. And in spite of the occasional issue, such as the 9 speed, it is still well below most luxury cars in maintenance costs. Just talk to a Mercedes or BMW owner.
 

·
Registered
Joined
·
573 Posts
Discussion Starter #30
I'm confused - you are quoting me about the glove box/console lights, but asking about the flashers?

The only lights that need resistors are the four flashers, or turn signal, lights. The rear lamps are basic single filament, and aftermarket LED bulbs should just work, or possibly rotated 180°. The cable to the lamp is 2-conductor, and the resistor is connected between the two conductors.

The front amber flashing bulb has two filaments: one is always on (parking lights) and the other is the flasher/turn signal. There are 3 conductors: a 12V+ for each filament, and a common (12V-) for both. The resistor is connected between the flasher filament 12V+ and the ground (common, 12V-). All T10 sockets have a provision for 4 contacts; single filament bulbs either have 2 contacts or 4, with opposing sides the same. Two filament bulbs have 3 unique contacts, with the 4th either unused or duplicating ground IIRC.

In their wisdom (?) Acura designed out the pluggable/replaceable flasher relay, and built the flasher circuit into the car's electrical system. But it appears that they kept the old (cheap) system of flashing, which IIRC uses a bi-metallic strip that turns on and off with the heating caused by the current, and is thus subject to hyper-flashing. But they do isolate the flashers on a trailer so that it doesn't cause hyper-flashing with the OEM trailer wiring kit. Why they didn't just design it with a simple timing circuit is beyond me... it would have cost pennies.

I have not owned a luxury German car, but my understanding is that they do deal with these details well. The MDX isn't really in the same category; it is somewhere above the mass market, such as the Honda Pilot, and below the luxury category. That suits me as the price is commensurate with the market position, and the MDX is quite satisfying to me, if imperfect. And in spite of the occasional issue, such as the 9 speed, it is still well below most luxury cars in maintenance costs. Just talk to a Mercedes or BMW owner.
I just replied to that post as ur first sentence was in regards to the resistor, and didn't take time to remove the rest of the quote.

I thought since it was single filament (7440) that there'd only be 2 wires and I could just attach resistors to bridge those 2 but wanted to be sure. Before I tore it open I wanted to know if I had to have a wire tester in the event there were 3 wires but since only 2 I'm good. All the rest of the info in ur post I was already aware of from ur previous posts which have been very educational and helpful so thank you.

I've never paid any attention to lights in my vehicles before as my past 2 infinitis already had led brake lights, only the mdx doesn't. Which is funny because in 17 they redesigned the front lights to be all led (including flashers) so why they left the rear flashers and brake lights as incandescent when nearly every other vehicle has migrated to led I have no idea. They saved what, maybe $10 per vehicle if that?

Sent from my SM-G975U using Tapatalk
 

·
Registered
Joined
·
573 Posts
Discussion Starter #31
Also am I correct in my understanding that the resistors for rear turn signals would only be drawing current when the rear turn signals are on, and the rest of the time would not have any current? If so then I shouldn't really need to worry about heat from the resistor as it would barely be on anyway (only use blinkers for a few minutes at a time with rest in between). Where if they were for the rear lights or possibly brake lights then they'd probably be on more and drawing much more current which would cause much more heat.

So since it's just for the rear turn signals which aren't used for very long each instance then double sided tape for mounting should be fine. If they were on a lot more then maybe I'd use self tapping screws into metal.

Sent from my SM-G975U using Tapatalk
 

·
Registered
Joined
·
18 Posts
I'll put the links in with the bulb links I'm putting together.

You know how hot an incandescent bulb gets, right? Well, putting more heat into an LED bulb is not a good idea as they already are dealing with the heat of the LED. The proper resistor will be mounted in an aluminum case for heat dissipation. These are sold with taps which make it very easy to attach to the wiring. The taps should not be used to hold the resistor in place; either screw into the MDX body, or better just use double-sticky foam tape to mount in place. It is very quick and easy to do while you are changing the bulbs.
I’m currently switching my ‘05 MDX tail lights to LED.

Do you know which 2 colors wires do I connect the load resistor to (there is red, green, and black going to each tail light bulb connector)?
 

·
Registered
Joined
·
558 Posts
I do not know the color scheme but it shouldn't be too hard to work out. There will be a ground wire (-12V), probably black, a wire for the running light that is constantly on (+12V), and a third for the brake light (+12V). I don't know if a resistor is even needed for your car, or maybe two. They are put between positive and ground. You really should be posting this in the 1st gen MDX section, not the third. Someone there should know.
 

·
Registered
Joined
·
18 Posts
I do not know the color scheme but it shouldn't be too hard to work out. There will be a ground wire (-12V), probably black, a wire for the running light that is constantly on (+12V), and a third for the brake light (+12V). I don't know if a resistor is even needed for your car, or maybe two. They are put between positive and ground. You really should be posting this in the 1st gen MDX section, not the third. Someone there should know.
Thanks for your message!

Oops, I just commented on an old thread I guess it was in the wrong place.
 
21 - 34 of 34 Posts
Top