How-To: Fix dead OEM HU LCD backlight
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How-To: Fix dead OEM HU LCD backlight This guide is for 4th gen Firebird/Trans Ams! Haven't seen the inside of a Camaro HU to compare. Anyways, this fix cost me $1 (assuming you already have the tools and soldering materials), so it was a lot cheaper than buying a new HU and took less than an hour (I'm slow 
) to perform the replacement.
Have you ever had your LCD display stop working on your OEM Delco HU? Chances are, it's just the light bulb that went out. The LCD displays use a very small incandescent bulb as a backlight, and mine went out several months ago. Couldn't locate a cheap/broken HU to part out, so I went to the local "ma and pa" electronics store today to buy a bulb. If you can find a cheap/free OEM HU to part out, I'd recommend doing that instead. It's much more simple that way.
Anyways here's what you need:
I don't have the exact part number/type for the replacement bulb, but I can get it soon. I just showed someone the OEM bulb/socket @ the electronics store and he had one that was smaller, but very similar design and fit into the OEM bayonet socket. He said that anything more powerful was larger in size and probably wouldn't fit.
Let's get started!
) to perform the replacement.Have you ever had your LCD display stop working on your OEM Delco HU? Chances are, it's just the light bulb that went out. The LCD displays use a very small incandescent bulb as a backlight, and mine went out several months ago. Couldn't locate a cheap/broken HU to part out, so I went to the local "ma and pa" electronics store today to buy a bulb. If you can find a cheap/free OEM HU to part out, I'd recommend doing that instead. It's much more simple that way.
Anyways here's what you need:
- Someone with soldering skills
- A workbench (not really necessary, but it sure helps
) - Tools necessary to remove OEM H/U out of car
- Soldering iron and some small (sewing needle diameter) rosin-core solder
- Something to hold the bulb socket while you solder
- Replacement bulb (check your local electronics store - bring the dead OEM bulb+housing for them to look at)
- Dead OEM bulb+bayonet socket
- Small wire clippers (probably optional - scissors would work too)
I don't have the exact part number/type for the replacement bulb, but I can get it soon. I just showed someone the OEM bulb/socket @ the electronics store and he had one that was smaller, but very similar design and fit into the OEM bayonet socket. He said that anything more powerful was larger in size and probably wouldn't fit.
Let's get started!
- Remove OEM HU from car, take to workbench.
- Use a small flat-head screwdriver to detach the clips holding the faceplate onto the HU cage. Slide the faceplate forward until you can see the brown circular plastic thing above the LCD. That is the bulb+socket that you need to replace. It is a bayonet mount and fairly easy to remove.
- Twist the bayonet socket counter-clockwise 90 degrees and lift it out of the HU. Check for the bulb for damage. If the bulb+filament look fine, then it's likely a different problem and you can stop here. If it's definitely the bulb, continue on.
- BUY THE NEW BULB (if you haven't already)! When you can continue working on the HU, proceed to next step.
- The bulb is attached inside the socket via thin copper wires (just like the replacement bulb you got). Twist the bulb back and forth while pulling until it comes out of the socket.
- Take the new bulb and thread the wires through the holes where the old bulbs wires went. Insert the bulb so that it fits snugly in the socket. Bend the wires so that they rest on top of the contact points.
- Find something safe to hold the socket while you solder everything up.
- With the socket held by something other than fingers (DUH...), solder the wires to their respective contact points. You'll want to make sure that the wires cannot break free of the metal tabs on the socket. Twist the bulb around a tiny bit to see if the wires move. Also of note is that the solder should not pile up above the level of the plastic. If it does, it is more likely to make contact with the cage upon reassembly and short something out. If you are having trouble with the solder piling too high, but not having trouble making a good connection, you could use a small file to grind down the excess solder to the proper height.
- Cut the excess thin copper wires at the ends of the contact points so they don't hang over and cause a short after reinstallation
- After making sure everything looks good (solder not too high, wires securely attached), screw it back into the PCB on the HU. I put two small pieces of electrical tape (one over the other) on top of the brown bulb socket to make sure the solder joints wouldn't short out on the HU cage.
- Re-assemble HU and test!
Last edited by ZexGX; Oct 1, 2008 at 05:41 PM.
