88 Blazer dash bulbs short? Minimal to no light from bulbs.

[Pickle88]

Changed the dash bulbs about a month ago to LED from the standard bulbs, without issue. Worked great and all of a sudden they stopped working. Upon inspection of the bulbs, instead of lighting up all of the way they are super dim, I can barely visualize 3 dots of light on each side of the bulb.

Fixed headlights about a month ago, have new headlight switch, verified good volts from the green wire (dash lights) from the headlight switch with a volt-meter. The guy that owned it before me did a crap job on the radio, so I have disconnected and removed the radio just before the dash stopped working. Curious if this sounds like a short to you guys. Or does something from the dash lights circuitry work off the radio too? Lost, any help would be greatly appreciated. Will try to get a picture in a little bit. Thanks.

 

[Pickle88]

Should add that I checked all fuses too.

 

[6872xtc]

Did you check that the ground is still good? I know that you checked voltage coming from the headlight switch, but what about checking voltage at one of the light sockets? Maybe there is a problem at the plug for the cluster.

 

[Pickle88]

Did you check that the ground is still good? I know that you checked voltage coming from the headlight switch, but what about checking voltage at one of the light sockets? Maybe there is a problem at the plug for the cluster.

Didn't even think about trying that, will give it a try. Thanks

 

[ZooMad75]

The printed circuit where the main connector plugs into the cluster is a weak spot. Sometimes the copper circuit can delaminate from the plastic and get mangled when you go to plug it in. Also, the factory radio did have an illumination bulb to light up the dial that was on the instrument light circuit. Just like the heater control has a light for it too.

If the light circuit was shorted, you would have popped the instrument lights fuse. My bet is the ground has a problem. Or the dimmer is turned down. LED's don't have enough resistance to allow the dimmer to work correctly, so the lights don't ramp up or down smoothly when the knob is rotated. Mine tend to blink slightly when I turn them off full bright and then just go out when the knob isn't quite halfway through it's travel.

 

[Pickle88]

Well the sockets have 8.4 volts but when I tested it the dimmer was all the way open. I have tried to open dimmer all the way up and no changes. Pulled fuses as well as tested them with a voltmeter. Radio is completely out unplugged at the connector clip. Maybe the circuit on the back. I have no experience with disconnecting the speedometer cable to get the cluster out, I can feel it in the back but no idea how to detach it.

 

[Sgyates27253]

there should be a metal clip rite behind gauge. while holding cable use finger to push clip forwardand pull back on cable at same time it should pull rite out..maybe its pull clip back....cant remember one of the two

 

[ZooMad75]

Before you go pulling the cluster, focus on the area that seemed to have impacted the lighting. Check your wiring to the factory radio connector. See if you have the same voltage on the light circuit there as you do at the headlight switch. By the way, 8.4 volts is LOW, even more so if the engine is running and the alternator is putting out 14v. A high resistance to ground would cause this type of voltage drop, or a broken wire that can only carry so much load, so it behaves like a resistance and cuts voltage.

 

[scpaul]

Under load, the 8.4 volts is probably going even lower. Since the radio had a light in it that was tied to the same circuit as the panel lights, I'd bet that there was another ground on the radio end of the circuit. If installed in the right places, additional grounds wires won't hurt.

Good luck, Paul

 

[scpaul]

You probably already know this but, I just thought about mentioning something, check to make sure that the control for the lights control the pos. side of the power. It probably does, but if it controls the ground side you might try spraying some contact cleaner, preferably non-residue (lube) unless the control is pretty well sealed. You could disconnect it and use a V.O. Meter, preferably a sweep needle, the needle makes the resistance changes more noticeable. With it out of circuit, you could check the resistance being even no matter weather Pos. or Neg. If the switch has different circuits that you pull the knob to get to, you can test them too.

Good evening, Paul

 

[scpaul]

I didn't say part of that right. On some stand alone electronics, like a radio, they leave the pos. side hot inside the radio and control the isolated circuit by switching the isolated circuit on and off with the ground. It has to be a stand alone isolated circuit or you would get a short, how bad would be determined by the amount of resistance in that circuit. Since the vehicle is neg. ground, this would be for totally isolated circuits only.

When I said it probably wasn't, I should have said that there isn't 1 chance in 1000 that anything like this would be the problem.

It still doesn't sound like what I'm trying to say, but it's as good of an explanation as I can give right now. The words just won't come out right, sorry.