I have had trouble with the turn signals on my GMC 4905 since virtually the day I bought it.
I have replaced ground wires, bulb bases, bulbs, wires, etc. but this week I went to check the turn signals and I had nothing!!!
I though ---Great!! The Flasher unit finally gave up the Ghost!
So I started tracing the power. First I started at the flasher unit. I popped the connector apart at the flasher unit and checked the fuse--Well it is good. Next I checked the voltage which was reading 9 volts--WHAT???
Next I moved to the connections at the Driver's seat junction panel. Good at the circuit breaker at the driver's seat junction box(after removing the 8 screws that hold the panel cover). I sure wish I had put the driver's seat on some sort of quick disconnect instead of re-using the factory base. It is hard for old fat people to lay prostrate on the floor to get to those bottom bus bars.
So then I moved back to the flasher unit. I checked the contacts inside the inline fuse. YES--Totally corroded--after attempting to sand the contacts still only getting 11 Volts. So, I cut off the end and check the voltage to ground--24 Volts. OK, so after a trip to AutoZone for a new inline fuse holder, and a quick install I now have flashers!! This bad connection has probably been the source of my problem all along!
BUT, since I installed LEDs on the rear they blink REEEEAAAALLLLY SLOOOOOW!!
I know somebody here solved that with a resistor in parallel with the positive line to the LED, but what I forgot was the resistance needed and what the nomenclature is for that resistor. Since Radio Shack is long gone I need some suggestions for where to get these resistors.
Any and all help is greatly appreciated.
Steve Toomey
As far as what resistor to use I don't know but I do know another solution. If your blinker unit is anything similar to a car you should be able to replace it with a flasher unit. The difference here is that a blinker is electromechanical and relies on the resistance for timing while a flasher is a simple solid state device that will output a steady blinking pattern whether its hooked to an LED or a heating element.
Finding one for a 24v system might be a pain but I guarantee they exist somewhere.
You can get LED bulbs with the resistor built in.
Now that you have the voltage situation worked out though, have you thought about trying the incandescent bulbs again to see if they are bright enough? To me the reason I put LED bulbs in the house system was to extend the run time on the batteries, but I'm not concerned about that with the chassis bulbs. My incandescent bulbs are plenty bright and easy to see.
Half the reason is the life expectancy of leds. Thats why trucks went to then. Fewer DOT hits for lights out.
Here's a 24 volt led flasher, and not from China.
https://www.pmlights.com/products.cfm?cId=5&fId=23&pId=896
My goal with the LEDs was to BE SEEN!!
I have the Truck Lite LEDs for Turn Signals, Brake Lights, and Tail Lights. I now have four big TAIL LIGHTS and FOUR BIG BRAKE LIGHTS and can be seen from behind.
Nobody can say they couldn't see me when coming up behind me fast.
I will probably put LEDs on the front turns signals too when I get the resistance problem figured out.
The housings for the front turn signals need some work, as the screws for the covers are all stripped out.
Steve