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I pulled my CE panel on my 89 S4 a month ago to clean and found one wire melted down that runs from F15 to the right door switch. I ran a new wire pending a new switch arriving without any problems. So today, I pulled the drivers side switch and all looked good. Then I found the rear hatch light was broken where the green wire attached and the white wire connector corroded where it attaches. I had another light so I put a new connector on the white one and hooked it up. I hooked the battery up and the cabin filled with smoke as the other two br/wh wires going to F15 melted down. Any ideas what the hell happened? I double checked the rear light wiring and it looks fine. Also, until I get this figured out, can I snip the wires at F15 or is there a fuse I should pull so I can drive the car? I have no problem going without interior lights for a bit. The red wire is the one I ran to the right door switch with the other side not connected or touching anything.
from the sound of it you wired the hot wire to the ground of the lamp in the hatch.
NOTE these interior lamps can be easily miswired since they changed the wire colors going to the hatch lamps .
since you let the smoke out of the wires it would be prudent to remove the powered wire thats going to the lamps.
I would suggest that you disconnect the battery and removal all of the lamps in the roof and hatch to verify they are all wired the same way
NOTE you can also inspect the door entry lamps as well.
Last edited by Mrmerlin; May 27, 2024 at 04:38 PM.
The door switches are switched grounds - stock red wires are battery power. You connected battery power to ground - presumably without a fuse. The red wires for interior lights only go directly to the bulbs - all switching - incl. from the relay is on the ground side.
The door switches are switched grounds - stock red wires are battery power. You connected battery power to ground - presumably without a fuse. The red wires for interior lights only go directly to the bulbs - all switching - incl. from the relay is on the ground side.
Alan
Just to clarify, that red wire going to the CE panel is the new one I ran to the door switch and is actually not even connected. It's just the color wire I had on hand and didn't want to wait to find some br/wh to make it match. Also, here is the wiring at the light, which I believe is correct based on posts I found in here when hooking it up. Maybe something happened when I pulled the left side door switch? That is one of the wires that melted if I read the diagram correctly.
Somewhere along the lines, I am thinking a terminal 30 wire found a connection it wasn't designed for. I would very diligently comb a wiring diagram to see how/where this could've happened. Make it so that it won't happen again & replace the affected wiring, and the Lucas smoke of course.
That light is correct - but they all need to be correct, any incorrectly wired light will cause you problems - you need to check them all.
Alan
Definitely plan on checking them all and obviously need to do some rewiring. Just wierd I didn't have an issue until changing this broken light and checking the left side switch. In the meantime, is there a fuse I can pull, or disconnect every light, so I can drive it?
Of course I'm also concerned if there is any damage to other wires around these within the wiring harness. The battery was only connected very briefly, but you see how much damage was done in the first pic.
Last edited by Steven Harper; May 27, 2024 at 09:50 PM.
its also possible the light frame was grounded to the chassis and the hot wire touched the ground,
but if the wires melted all the way to the back of the car thats were to look .
]\otherwise a common short is over the mirror you should replace these old lamps with the Jetta versions
On a related note, does anyone know of a replacement terminal for the ones in the plugs? I pulled the crimp apart when running the first wire to reuse it but don't have faith it will withstand that a second time. I found part number 999 652 451 22 that is no longer available and can't find specs on it to match it up with another brand.
Check with Roger on terminals (ROG100 - 928sRus). Pull Fuse #7 / #24 or the interior light relay XXI to disable the interior lights. Is the interior light relay the correct part?
Also what size Fuse(s) are currently being used?
Should be no greater than 5amp, I've seen greater values installed by PO's, this will cause smoking/melted wires before the fuse lets go.
Check with Roger on terminals (ROG100 - 928sRus). Pull Fuse #7 or the interior light relay XXI to disable the interior lights. Is the interior light relay the correct part?
Alan
Just checked and it is the correct relay and 5 amp fuse. My biggest concern now is if this melted into other wires in the loom. Crossing my fingers that it didn't but we'll see when i dig into it. It definitely burned the wire inside the left door pillar that was fine prior to this.
Note the lamps are driven by the relay - so they almost certainly have nothing to do with the door wires - they may have issues anyway - but unrelated to this.
The door pin switches connect only to ground (direct grounding) and to the Brown/White wire that triggers the interior light relay - the only other places they connect are the Power Window Regulator Relay (USA version stays active until a door is opened) and the Timing (chime) Relay in the console (used for key-in door open, door open marker lights on and door open parking lights on chimes). Have any of these areas been touched recently? If no I'd suspect the power window relay of having a fault - it should have a weak pull-up on the T-pin but if that pin were shorted to B+ it would get the results you have. You could remove the relay and use DVM to see what resistance there is between T and 30a and also between T & 15a. You can also measure resistance to ground from the T pin in the relay socket (this is the wire that connects to the pin switches).
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Interior Light Wiring Meltdown
