Instrument lights failure with LED Taillights

[rv8pilot]

I recently installed a pair of genuine made-in-china taillights in my 2001 Yukon XL. These units had load resistors on the turn signals but nothing on the brake or parking lights. The lights worked fine and I am satisfied with them in that respect. However, I discovered that my cruise control no longer worked so I ordered a set of plug-and-play (wired with connectors) resistors which had a 6 Ohm/50 Watt resistor for the brake lights and one for the parking lights. After some tribulation with blown diodes and circuit wiring all worked and the cruise control also worked. However, now My instrument cluster and radio cluster lights go out when I step on the brake. There may be other issues as well but they have not surfaced yet as I just discovered this today as I was shifting out of Park and the gear indicator went black. As soon as I released the brake it came back on. The Service Engine Soon light was unaffected (its on because of crapped knock sensors, or at least their indication as there is no knocking from the engine).

If anyone has any clue at all why this is happening I'd very much appreciate your insight, its driving me nuts.

An update on this issue: Last night I checked to see what happened when the headlights/parking lights were on with the result that the instrument lighting worked fine. With the low light level with the headlights off I could see that the cluster lights were not off entirely but very dim, too dim to be seen in daylight. Hope this helps some.

Thanks,
Andy

 

[rv8pilot]

Here's Update #2: Last night I tried the lights again and noticed that the CHMSL was on whenever the taillights were lit and the taillights were very bright. They brightened a bit on braking but not by a lot. Obviously this was NG so I disconnected the load resistors and the light s are back to normal operation including the instrument lighting. Now, of course, the cruise control does not work so the issue is how to get it to work without affecting something else. Any ideas?

 

[clandr1]

If the aftermarket lights aren't working as designed, I think you should contact whoever you bought them from and ask for an exchange.

 

[rv8pilot]

Update no. 3 and hopefully the last: As I mentioned earlier, there are a pair of load resistors in each setup, one for the parking/taillights and one for the brake lights. Their wiring has a female connector that mimics the vehicle harness connector and a male that mimics the bulb base. As you all likely know some of the bulbs can be plugged in two ways since the direction of the current doesn't matter in an incandescent bulb. Not so with LEDs. Since there are two new connectors per setup there are four ways to plug them in. Apparently, I had tried three of the four. This morning I got at it again and finally hit on the right combination and everything works properly, even the cruise control. So, if any of you are considering a change to LED taillights, keep at it if they don't work at first, there is probably a solution. It looks like the load resistors are necessary on all the circuits to avoid problems. I'm not sorry I spent the extra $15 or so for the wired plug & play setup as it allowed easy experimentation.

Interestingly, the load resistors that came with these el-cheapo lights on the turn signals are really a better setup than the fancy single aluminum finned gold anodized units. They used three 20 Ohm/20 Watt resistors wired in parallel. This makes a resistor of 6.7 Ohms and 60 Watt capacity and as a result, they don't get nearly as hot as the single 6 Ohm/50 Watt resistors and don't require heat-sinking.