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1993 4.9L Seville - X920BT Navigation w/ backup cam, Flowmaster 40 Series Exhaust
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472 Posts
Discussion Starter #1
The two park/stop lights on the inner, rear, driver's side tail light are acting up. See pictures below - in drive without the foot on the brake neither light up; when braking only the outer 3057 bulb lights up; in reverse the backup light properly lights up. So the out 3057 bulb sometimes works, middle 194 bulb never works, and the reverse bulb works fine.

Here is what I know the problem is NOT from process of elimination:
  • Bulbs
  • Fuse
  • The 1ft long harness that connects behind the tail light and contains the sockets for the three bulbs

So my next thought is the connector that plugs into the tail light harness, or a bad ground somewhere? What should I check next? Thanks





 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,551 Posts
Check the wiring harness where it exits the left trunk hinge bracket - inside the plastic trim cover. The harness/wire sometimes bends and chafes there, causing a break. Also, check the harness ground at the body metal on the left fenderwell side, under the carpet.
 

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1993 4.9L Seville - X920BT Navigation w/ backup cam, Flowmaster 40 Series Exhaust
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472 Posts
Discussion Starter #3
Check the wiring harness where it exits the left trunk hinge bracket - inside the plastic trim cover. The harness/wire sometimes bends and chafes there, causing a break.
I didn't even think of that, but that's where the problem turned out to be. Thanks!

The area was taped up so tightly that the bundle had very little flexibility. I think that aggravated that spot which was already susceptible to splitting. I think afterwards I'm going to leave it a little more "open" so it isn't so tight.



What gauge wire is that? 20? Need to swing by Lowes, I used up the last of my red 20 gauge wire when I installed the nav unit.
 

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1993 4.9L Seville - X920BT Navigation w/ backup cam, Flowmaster 40 Series Exhaust
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472 Posts
Discussion Starter #4
Bump. Anyone able to confirm the gauge of that wire?
 

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White Diamond '03 DHS (with DTS floor shift)
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Why not just solder them back together and shrink wrap the joint?
 

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1993 4.9L Seville - X920BT Navigation w/ backup cam, Flowmaster 40 Series Exhaust
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472 Posts
Discussion Starter #6
Why not just solder them back together and shrink wrap the joint?
Fair question. Because I suck at soldering, much less while laying on my side/back in the trunk. That notwithstanding, the wire is fairly short in that area and doesn't seem like there is much slack to soldering it back together. I do have heat shrink wrap however.
 

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1993 4.9L Seville - X920BT Navigation w/ backup cam, Flowmaster 40 Series Exhaust
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472 Posts
Discussion Starter #8
Bump. Anybody know the gauge of that wire? I'd really like to get my Seville back on the road.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,551 Posts
The wiring diagrams in the GM/Helm service manuals (eBay or www.helminc.com), or the same manuals in a subscription to www.alldatadiy.com, have wire gauges alongside the color/wire number legends.

Looks like #14 or #16, BUT if you solder in a short length of either of those gauges (even if the true harness gauge is #16 or #18) it will make NO difference.
 

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1993 4.9L Seville - X920BT Navigation w/ backup cam, Flowmaster 40 Series Exhaust
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472 Posts
Discussion Starter #10
The wiring diagrams in the GM/Helm service manuals (eBay or www.helminc.com), or the same manuals in a subscription to www.alldatadiy.com, have wire gauges alongside the color/wire number legends.

Looks like #14 or #16, BUT if you solder in a short length of either of those gauges (even if the true harness gauge is #16 or #18) it will make NO difference.
Thank you. I have the 1993 FSM for the Seville/Eldorado, but I had trouble figuring out the wiring diagram when I was initially trying to pinpoint the issue.
 
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