CHMSL LED bulbs to replace two 1156 bulbs; need resistors?
08-20-2012, 11:20 AM
#1
CHMSL LED bulbs to replace two 1156 bulbs; need resistors? On a vehicle with two 1156 bulbs in the CHMSL, I want to replace the bulbs with LED ones for less heat. The ones purchased don't work but I know resistors are able to put enough load to make them work.
The LED bulbs do work on 2amps from a battery charger. But not in the socket with 12v 2amps applied to the socket connector (the sockets can be removed from the car, they have a pigtail on the side.) The sockets I'm testing with are brand new GM parts.
1 LED / 1 regular bulb doesn't work in the car. The 2 sides of the sockets both have great continuity.
How do I determine correct resistors to make the LED bulbs work without causing issues?
I think the 1156 is a 2.1ohm load @ 12v. There are two and they're wired in series. It's a GM vehicle but the CHMSL was replaced by Cars & Concepts so it's an OEM approved non-stock part. Do I need to pull schematics to see what else is on the circuit?
The LED bulbs do work on 2amps from a battery charger. But not in the socket with 12v 2amps applied to the socket connector (the sockets can be removed from the car, they have a pigtail on the side.) The sockets I'm testing with are brand new GM parts.
1 LED / 1 regular bulb doesn't work in the car. The 2 sides of the sockets both have great continuity.
How do I determine correct resistors to make the LED bulbs work without causing issues?
I think the 1156 is a 2.1ohm load @ 12v. There are two and they're wired in series. It's a GM vehicle but the CHMSL was replaced by Cars & Concepts so it's an OEM approved non-stock part. Do I need to pull schematics to see what else is on the circuit?
08-20-2012, 03:06 PM
#2
Copy & Paste Moderator
Its not a resistor issue. It is most likely a polarity issue. Since you can remove the socket and power it remotely, swap which you connect to positive/negative and see if the LED works.
LEDs only work in one direction. Incandescent bulbs will work either way.
LEDs only work in one direction. Incandescent bulbs will work either way.
09-07-2012, 06:54 AM
#4
I suspect you're not getting a good ground through the casing of the socket. If you have your charger with just stripped wires, try this - connect the positive to the socket lead as normal but connect the ground by pushing the stripped ground wire into the side of the socket between the bulb and the housing. 1156 bulbs are not subject to polarity issues because they are bayonet-type connectors but they sometimes fail to make good contact with the outer barrel of the socket that provides the ground side of the circuit. If that is the case you can usually fix it by giving the barrel a bit of a squeeze with some pliers to pinch it tighter against the bulb base (do it without the bulb in the socket in case you squeeze too hard).
09-07-2012, 04:08 PM
#5
It's a plastic GM socket which pigtail-connects to the wiring but I think I can apply what you're saying by touching (-) wire to the bulb's metal base. It isn't that the contact strips in the socket have poor conductivity per se but I can see why they might not have good contact against chinesium.
09-07-2012, 04:12 PM
#6
Inside the plastic outer casing should be a metal barrel with the two slots for the bayonet push and twist pins on the bulb. The ground pigtail will have been soldered to that barrel someplace inside the socket. The barrel is usually fairly thin metal that is easy to bend even with the plastic out casing around it. It doesn't have to be moved much - just enough to make better contact with the outer side of the bulb.
