P L E A S E R E A D T H I S F I R S T :
It is very important that you only remove and replace one bulb at a time.
Do not remove/replace additional bulbs until the first bulb is working properly.
A missing or improperly installed bulb can effect other bulbs in remote locations of the vehicle and this can become very confusing.....very quickly.
When inserting cluster leds, always touch the metal or plastic bases only. Avoid touching, bending or pushing on the little led bulbs. Many of the led bulbs we sell have multiple led clusters. The leds bulb clusters are delicately soldered to circuit boards inside. When installing leds, care should be used to not push or put pressure on the individual bulbs in the cluster. If the leds are bent or pushed on, they may become detached, or cause the circuit board they are attached to to become delaminated and then some of the leds may not light.
194 168 921 906 74 LED Wedge Bulbs
These bulbs are all quite simple to install. The 921/906/196/168 bulbs all have the same base and can be inserted in the same socket and used interchangeably as long as the bulb will physically fit in the space.
These all have two separate wire contacts protruding from the bottom. One of these two contacts is the common negative (-) ground. The remaining contact is the positive (+) side of the circuit.
When installing the bulbs you will notice there is no orientation features and they can be inserted 2 different ways by rotating the bulbs 180 degrees. In order for the bulbs to light, the bulbs must be inserted so that the common negative contact is connected to the negative lead in the socket.
It is best to determine which contacts are (+) and (-) using a meter, however if this is not practical, the bulb may be briefly inserted to see if it lights.
If it does not light, the bulb should be removed ASAP to avoid damaging the bulb and/or blowing fuses. Remove the bulb, rotated 180 degrees and reinserted before reapplying power to the bulb. As always, only remove/install one bulb at a time to avoid compounding issues.
If the bulb still will not light, then it is most likely not getting power due to poor electrical contact or a possible blown fuse. The old incandescent bulb can be reinserted anytime to verify that the socket is receiving power. The wire contacts also can be adjusted to get better contact.
These, like all leds, must have the proper polarity in order to light up in a DC (battery powered) circuit. Most factory wired cars are already wired so that the bulb will properly connect, but only if the bulb is oriented properly.
In some cars, the small wedge base sockets have the contacts opposite so they won’t align with the bulb no mater how it is rotated. If the contacts on the bulb are on the wrong side to align with the socket, you can bend the wire contacts on the bulb around the base to the other side so that they align with the contacts in the socket. Caution should be exercised before bending the contacts to avoid having to bend them back and forth. The contacts are brittle and should only be re-bent one time to avoid breaking them off.
You can check more in:
Leds Instalaltion Tips