I just picked up the car from a gentlman that has not been able to get the car to pass az emissions. Long story short, I got the car for a good deal. The rear right taillight is not working (no brake lights, no turn singals, and no back uplight). All of the other lights functions as normal. It's just the rear taillight. Any help would be greatly appraciate as I need to get the car inspected prior to emissions and they wont allow it to pass with out all the lights functioning.
Right Taillight Not Functioning...
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wmburns
SN Certified Technician
+1 on above. Check the ground (but not in the way that you think). However I happen to know that both sides are grounded at the same point in the trunk. So for the ground to be good for one side and bad for the other would have to mean a break in the wiring harness.
I believe the actually green grounding bolt is on the left side of the trunk. It will be necessary to remove the trunk liner.
The wiring harness passes from right to left near the license plate from inside the trunk. If this were my car, that's the first place to look for wiring harness damage.
If unable to find obvious wiring harness damage it time to get out the Volt-Ohm Meter (VOM). Use the VOM to test for +12 volts on the left side using a known good ground (the green terminal in the trunk for example). Once voltage on the left side has been confirmed, test for +12 volts on the right side.
Once +12 volts has been confirmed on the left side using the known good ground, re-test using the ground inside the socket. Should this test fail then the diagnosis is confirmed. It now becomes a matter of finding where the actual break is.
I believe the actually green grounding bolt is on the left side of the trunk. It will be necessary to remove the trunk liner.
The wiring harness passes from right to left near the license plate from inside the trunk. If this were my car, that's the first place to look for wiring harness damage.
If unable to find obvious wiring harness damage it time to get out the Volt-Ohm Meter (VOM). Use the VOM to test for +12 volts on the left side using a known good ground (the green terminal in the trunk for example). Once voltage on the left side has been confirmed, test for +12 volts on the right side.
Once +12 volts has been confirmed on the left side using the known good ground, re-test using the ground inside the socket. Should this test fail then the diagnosis is confirmed. It now becomes a matter of finding where the actual break is.
After some tests, the rear passanger light is not getting any power, the ground is good. I tested the lights using the power from the left tail light and everything turned on as normal. I followed the wire harness all the way down to what was visible with out tearing the rest of the car apart. No damage was found.
wmburns
SN Certified Technician
Ok. Now things get "real".
If this were my car the next test is to verify there's power coming out of the multi-function switch OG/LB wire.
If there is power, then there's a wiring break in the harness. The wire path passes through several connectors (C202b,C265, C314, C408, C4114). Test the OG/LB wire at each connector to find out where the power stop. While there inspect each connector for evidence of water, rodent, mechanical damage.
This is where having a full set of Ford wiring diagrams are almost a must. Just too much information to post. If interested in getting a set for yourself I maybe able to help. PM if interested.
See what I mean about "getting real?".
If there's no power out of the multi-function switch OB/LB wire with the right turn signal activated then the problem HAS to be in the multi-function switch. Note, this seems unlikely to me because the dash turn signal indicator works.
If this were my car the next test is to verify there's power coming out of the multi-function switch OG/LB wire.
If there is power, then there's a wiring break in the harness. The wire path passes through several connectors (C202b,C265, C314, C408, C4114). Test the OG/LB wire at each connector to find out where the power stop. While there inspect each connector for evidence of water, rodent, mechanical damage.
This is where having a full set of Ford wiring diagrams are almost a must. Just too much information to post. If interested in getting a set for yourself I maybe able to help. PM if interested.
See what I mean about "getting real?".
If there's no power out of the multi-function switch OB/LB wire with the right turn signal activated then the problem HAS to be in the multi-function switch. Note, this seems unlikely to me because the dash turn signal indicator works.
I will take a look when I get home. I am going to jump the lights so I have everything except the Right turn singals just to pass emissions/inspection. I thought about the multi function switch too, but had the same thought since the turn signal indicator works and the front turn signal works too.
I will def need some wiring diagrams! PMing you now.
I will def need some wiring diagrams! PMing you now.
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