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Mon Dec 04, 2023 11:28 am

I just purchased beamtech LEDs to replace my halogen h4 bulbs.
Should I install load resistors and or change the relay for an LED relay?
I’ve installed the LEDs and while checking functionality, they go low and hi, but with the blinkers on, the LEDs dim in unison with the blinkers. The blinkers are regular incandescent bulbs, not hyper flashing but blinking a little slower, only noticed it because one side LED the other halogen and the halogen side blinks normal.
Brand new electrical harness, all negative points were cleaned as were all electrical connections on switches and fuse block: battery cables new and ground strap on transmission clean and new.
Basically, is this normal for LEDs? Or do I need to add resistors or LED compatible relay?

Mon Dec 04, 2023 11:33 am

Wanted to add, I did search and read through multiple threads on LEDs, but didn’t come across this issue, or if it’s really an issue and just the way LED headlights are

Mon Dec 04, 2023 11:37 am

Never heard of needing resistors on headlamps, just on turn signals with some blinker relays.

Mon Dec 04, 2023 5:39 pm

oibovveroi wrote: Basically, is this normal for LEDs? Or do I need to add resistors or LED compatible relay?
Not normal.
No additional resistors needed for LED headlights. LED headlamps are meant to be a plug-and-play replacement for incandescent headlights. They last longer, use less wattage and tend to be brighter.

Resistors are used when creating circuits with LED components (raw LED) to reduce the current that flows thru the LED itself. Most LED bulbs sold as replacement for incandescent bulbs have the needed resistors built in so they are plug and play replacements.
Resistors when used with turn signal bulbs are not for the LEDs themselves but for the OE flasher relays which expect the load from the original incandescent bulbs. The LED resistors in these cases simulate the load of two 25W bulbs (50W resistors). 25W incandescent corner turn signal bulbs draw more current than the 2W LED replacement bulbs (lower wattage is one of the features of LED bulbs). The OE flasher relays that came with the car often depend on having 25W x2 load from two corner turn signal lamps to work properly. These flasher relays either hyperflash or slow flash because the load is not correct. LED compatible flasher relays will work with either low watt LED bulbs or traditional higher watt incandescents.

oibovveroi wrote: ... but with the blinkers on, the LEDs dim in unison with the blinkers.
So you are saying when the turn signals flash OFF the headlights dim. And when the turn signals flash ON the headlights go bright? I sort of expect it to be the opposite way?

Some things to test/check...
Double check your wiring for the headlights. Here is a diagram from Speedy Jim's page showing the wiring of the plug as well as the bulb. Make sure you have not connected the ground wire to the wrong terminal on the headlight. This is a common mistake if your manually wired the headlight plug.

Remove the front parking/turn signal bulbs and test your headlights with just the rear turn signals and parking lights working. The turn signal relay may hyper flash since you are missing the front lights. Do your headlights still dim when the rear turn signals flash? If they work normally it suggests your turn signals are grounding thru the headlight/parking light circuit, or visa versa.

Check the ground connection for your front light assemblies. You could even use a jumper wire and directly ground the metal body of your turn signal assembly to a known good ground and see if the problem goes away.

Bypass the headlight dimmer relay. Removed the dimmer relay. Use a jumper wire and connect the white/black INPUT wire at the dimmer relay to the white OUTPUT wire (high beam). Then connect the white/black wire to the yellow OUTPUT wire (low beam). If this makes a difference it could mean you are using the wrong relay for the dimmer relay or it is wired incorrectly.

Mon Dec 04, 2023 6:36 pm

[quote="ashman40"] oibovveroi wrote: Bypass the headlight dimmer relay. Removed the dimmer relay. Use a jumper wire and connect the white/black INPUT wire at the dimmer relay to the white OUTPUT wire (high beam). Then connect the white/black wire to the yellow OUTPUT wire (low beam). If this makes a difference it could mean you are using the wrong relay for the dimmer relay or it is wired incorrectly.[/list]
I’ll try this, all the relays are original to the beetle so maybe it’s going bad?
It’s wired correctly per my Bentley manual schematic.
I removed the turn signal indicator bulbs with no change.
The headlight dims as the turn signal lights up.
The halogen light works fine.
Other than a possible relay starting to go out, possibly I got a defective set of LEDs?
This is a 71 super beetle with a Wolfsburg west wiring harness, the negative wires were defective in the harness and I’ve replaced those, I’ll also double check against your diagram for the socket wiring, are they wired different than vw? Again I check against your picture.
Pointers on what to check is appreciated, thank you for taking the time

Thu Dec 07, 2023 5:03 pm

oibovveroi wrote: This is a 71 super beetle with a Wolfsburg west wiring harness...
It’s wired correctly per my Bentley manual schematic.
'71 was the first year VW introduced the black/yellow wired "X" circuit coming off the ignition switch. This is a low priority circuit that is disabled while the starter is cranking the engine. In '71, only the headlights were on this circuit and it did not pass thru the fuse box. From'72-later fuse #10 was set aside and more devices (wipers and blower motor) were moved to this circuit. Power for your headlights start from this circuit. It runs to the X terminal of the headlight switch. From the headlight switch it runs to the dimmer relay. Does your dimmer relay have 4 or 5-prongs? The 5-prong dimmer relays have an extra #30 terminal which normally has constant 12v from the battery. Depending on the relay internals the headlights themselves are either powered from this #30 terminal or from the white/black #56 wire coming from the headlight switch.

oibovveroi wrote: I removed the turn signal indicator bulbs with no change.
The headlight dims as the turn signal lights up.
The halogen light works fine.
Other than a possible relay starting to go out, possibly I got a defective set of LEDs?
It doesn't make sense that your high watt (50W) halogen headlights work fine but your low watt (10W?) LED headlights are impacted by the turn signals. Unless your halogen install had a dedicated power source and relays for powering the halogen bulbs?
You can also confirm that your halogen and LED lights both function the same by making sure the function of the prongs on the headlights are the same.
Another test would be to use your battery jumper cables to bring a completely separate power source from the battery terminals and power your headlights directly from the battery and confirm if they are still impacted by the turn signals.
What is your battery voltage with everything OFF and then what is the voltage reading when your headlights are ON? A fully charged battery should read 12.6v with everything OFF. Turn the headlights ON and the voltage reading should drop some but never below 12.0v.

oibovveroi wrote: ... the negative wires were defective in the harness and I’ve replaced those,
This is worrisome. Brand new wires were bad? How were they defective? If one color wire was bad what prevents a different wire color from the same kit from being defective?

oibovveroi wrote: I’ll also double check against your diagram for the socket wiring, are they wired different than vw? Again I check against your picture.
The headlight plug diagram from Speedy Jim's page is the stock VW wiring.

You need to check that both of your headlights work when wired this way.
I've done some digging and can confirm stock 7" headlights and 7" halogen/H4 bulbs are wired the same... but some other headlights (not used on Beetles) may use a different wiring standard.

Fri Dec 08, 2023 7:44 pm

[quote="ashman40"][quote="oibovveroi"]
As it turns out, I did replace the headlight relay do to a problem I had with the dimmer in the new turn signal switch. Problem was in the switch itself, as I recall, you actually helped me with that issue, the tabs were stuck together. So I left the new relay in and put the original in the parts bin.
I went over my Bentley schematic and the headlight relay has a wire connecting to the hazard switch. Appears that’s how it’s on the blinker circuit. I briefly went over the 72 schematic and that one doesn’t appear to be connected to that chain of connection.
I may be wrong, but I think if I just go through and wire it as a 72, I’d probably solve the issue.
Yeah, the halogens do not have this issue. So at this point I believe it’s either defective LEDs, or they’re just too touchy and the connection to the hazard and therefore connected to the turn signals is causing the issue.
Hopefully I wrote my thoughts into this correctly.
Thank you for your help, but for the time being, I’ll be using halogen’s until I get the courage to redo the wiring as a 72.

Fri Dec 08, 2023 10:39 pm

oibovveroi wrote: I went over my Bentley schematic and the headlight relay has a wire connecting to the hazard switch. Appears that’s how it’s on the blinker circuit. I briefly went over the 72 schematic and that one doesn’t appear to be connected to that chain of connection.
Are you running a 4 or 5-prong dimmer relay?

The wiring diagrams have terminal numbers where the wires connect to the switch or relay. Which terminal on the dimmer relay connects to which terminal on the hazard switch???
I don't see any diagrams where these two devices share any connection??

I could see where the 5-prong dimmer relay with its extra #30 terminal shares a fuse connection with the #30 red wire that runs to the hazard switch. But this is just where the two share the same battery constant power source. Normally, I would expect the two to pull power from different battery constant fuses.

Please provide more specific details. I am concerned you may be reading the '71 wiring diagram incorrectly?
There are differences in the '72 Beetle wiring diagram. From '72-onward the black/yellow "X" circuit from the ignition switch runs to the fuse box and powers fuse #10. In '71 this circuit from the ignition switch only powered the headlights which were fused later in the circuit so the black/yellow "X" wire didn't stop at the fuse box. Fuse #10 in '71 shared ignition switch power with fuses #11 & #12. It was a one-year-only arrangement.

Fri Dec 08, 2023 11:18 pm

[quote="ashman40"] oibovveroi wrote: I went over my Bentley schematic and the headlight relay has a wire connecting to the hazard switch. Appears that’s how it’s on the blinker circuit. I briefly went over the 72 schematic and that one doesn’t appear to be connected to that chain of connection.
Are you running a 4 or 5-prong dimmer relay?

The wiring diagrams have terminal numbers where the wires connect to the switch or relay. Which terminal on the dimmer relay connects to which terminal on the hazard switch???
I don't see any diagrams where these two devices share any connection??

I could see where the 5-prong dimmer relay with its extra #30

My bad, I had took a quick glance, I was looking at the hazard relay and didn’t pay attention. Rechecked and my headlight relay is 4 prong relay. Not connected to the hazard relay.

Sat Dec 09, 2023 1:07 pm

Ok, understood.

Somethings you can test for and may lead to an answer for why your headlights pulse while your turn signals are flashing...
Check the voltage at the battery posts with everything OFF.

Place your voltmeter on the black/yellow "X" wire coming out of the ignition switch. Test for the voltage reading while the key is in the ON/RUN position, engine not running. The voltage difference between the battery reading above and this voltage reading represents losses from wire resistance and some small devices drawing current from the battery while the key is ON. Normally I'd expect a loss of 0.2v or so when the key is turned to ON.

Turn the headlights ON and note the change in voltage. Here the parking lights and headlights are drawing current. The voltage reading at the ignition switch should drop slightly.

Turn the turn signals ON and note if the voltage reading on the "X" wire is pulsing. I would expect the voltage on the black #15 wire to pulse as this is where the turn signals are pulling their current from. But X should not see a voltage change unless the red #30 wire is struggling to provide the needed current, or the battery is weak.

Repeat the above tests with the engine running and charging system maintaining a higher overall voltage level in the electrical system.
What are your voltage readings.

Power for both the ignition circuit (15) and the X circuit come from the single red (30) wire running from the fuse box to the ignition switch. Ideally, the amount of current passing thru this red wire should be enough to satisfy any demand from both the 15 and X circuits. When the current flow thru the red wire is insufficient, the current that does flow thru the red wire must be divided inside the ignition switch, some flows out the black wire where it powers things like the ignition coil, parking lights and the turn signals... and some current flows down the X circuit to power the headlights when they are turned ON. How much current flows down each path is basically determined by the resistance down each path. The lower the resistance the larger proportion of the current will flow. The higher the resistance down the circuit the less current will flow. Low wattage LED lamps = higher resistance. Your halogen headlights are high watt, low resistance and would draw more current. Your LED headlights are low wattage and so high resistance.
This lower current draw from LED lamps should mean there is a surplus of current available to flow down either the #15 or #X paths.

Try this test... find the red #30 wire coming off the ignition switch. Follow it back to the fuse box (it should connect to the INPUT side of fuse #8). Disconnect this ignition switch wire from the fuse box. Clean up the terminal so it is shinny clean and makes for a good electrical contact.
Using your battery jumper cables connected to your battery post... create a jumper wire to connect your ignition switch #30 wire directly to the battery positive terminal. The very thick jumper cable path should provide a circuit capable of providing all needed current directly from the battery.

Re-run the tests and see if there is less voltage loss at the 15 and X wires and also test while the flasher relay is flashing. If there is a noticeable improvement with less voltage loss than before it suggests the existing red #30 wire from the battery to the fuse box has high resistance and limiting the amount of current making it to the front of the car. This limited current capacity is being split/shared by devices and causing voltage drops.

Another area to test is to connect everything normally, but connect jumper cables between a 2nd carb battery and your existing Beetle battery. Just as you would if jump starting the car. The extra battery adds capacity to the "reservoir" of current available to the electrical system. Basically increasing the size of the battery. If this fixes your dimming issue it suggests your battery is weak. Take it to your FLAPS and have them charge and load test it. If your battery is over 5yrs old you should consider buying a replacement.