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Old 01-18-2006
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Rear Lights Failing & Mixed Up - Need Help

Hi, I'm driving an '84 Ranger 2.3 5-speed.

Two days ago the direction indicator stopped automically flashing on both left and right. No problem, do it manually, then change flasher or bulbs at next opportunity. Today driving in snow & freezing rain. By nightfall, I realize the brake lights, reverse lights, rear parking & indicator lights don't work.

If the main light switch is off, putting the tranny in reverse will bring on the reverse & brake lights, but they don't light if the main switch (headlights) is on.

The headlights and front parking & indicator lights are the only ones still working ok. I made it home tonight, but I need to know what might cause this mix up.

Where is the rear harness routed on an '84? This is a borrowed vehicle, so unfortunately I don't have the book. If the rain & snow hold off tomrrow, where should I look for a problem?

Where are the flasher and fuse box located? It seems like one major central junction for the rear wires is bent out of shape. Has anyone had this kind of problem? Please help me out if you've got any clues.

Is there an online wiring diagram database where I could search?

Thank you, Gordon

Last edited by gordonb1; 01-18-2006 at 09:04 PM.
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Old 01-18-2006
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I don't have a manual from 84 but I do have one from 89 - there MAY be similarities but I'm not sure.

With those interrelated symptoms, one possibility could be a bad ground. In the 89 manual, the brake, running and reverse lights all share the same ground point. It is located under the hood on the driver side inner fender about halfway back. The failure might not be at the ground point itself, though. The connector to the subharness that carries the hots and ground wire to the rear of the truck is near the master cylinder in the 89 book. I believe that the rear subharness runs down the driver side frame rail.

Good luck!
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Old 01-19-2006
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Thanks Bob,

Your answer makes perfect sense to me. And it could be the running lights (not the brake lights) that come on with the reverse light. I had a look this a.m. where you mentioned the ground connection, but there is a thick layer of anti-rust spray (20 years worth?) coating a lot of things, and no ground wires to the chassis or fender were evident.

I see the rear sub-harness going down into the rail, so I should be able to trace the ground. Just to confirm, is this ground point (on an '89) a separate wire from the harness which is attached to the inner fender(bolted onto a stud or stanchion). Am I right in guesssing that a separate ground wire is necessary because the light fixtures are not naturally grounded to the body, being plastic, etc? Am going out now to dig deeper.

Thanks for your help,

Gordon
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Old 01-19-2006
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Yes, the ground wire from the back of the truck should terminate at a ground bolt or stud midway along the front inner fender, visible when you open the hood. Again, I'm talking from an 89 perspective.
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Old 01-20-2006
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Thanks Bob,

First thing I found was the wires at the rear are a rat's nest - some broken and everything encrusted in ice, snow and some salt (for flavour). Part of the problem could be here, and it will take a hair dryer and then a soldering iron to clean it up. What I need is a wiring diagram for this rear harness so I can sort out the wires by color, and also find the (as yet) elusive ground point. I have a multimeter which will help, though I may need a test light to speed things up (?).

I found the alternator casing cracked & bearings almost shot, so this gets first attention - replacement arriving today.

Checked a wiring diagram for another car and it shows a common ground for all the rear lights. Makes sense. So does this mean that starting from the ground point, once the ground wire reaches the rear, that it is spliced many times to provide a ground for each light? This is not apparent to me yet when I look underneath, but I will clean it all up. There are a couple of connectors which I need to examine - maybe this could be how multiple ground wires are distributed (?).

Finally, when I repair these wires I will use shrink wrap to seal the solder bond. Should I put di-electric grease on the joint before sliding over the shrink wrap tube? These wires get heavy exposure to water, salt, etc.

Will post a request for a wiring diagram under a sparate thread topic.

Your advice is appreciated,

Gordon
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Old 01-20-2006
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Ford's color code convention for wires attached to chassis ground is black. In the case of the 89 Ranger, there are several splices within the wrapped harness that bring all of the black ground wires from the individual rear lamps together to a single black wire that runs forward to the underhood ground. These are the color codes from 89 and they are still the same in 2005:

Reverse: BK/PK
Running: BN
License: BN
LR stop/turn: LG/OG
RR stop/turn: OG/LB
Ground: BK

I use dielectric compound/grease on any connector pins and any splices that have a chance of being exposed to the elements.
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Old 01-20-2006
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Bob, thanks for looking up this info for me. Will let you know my progress.

Gordon
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Old 01-21-2006
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Hi Bob,

Thanks a lot for your help. Didn't get to the wiring on Friday but went out tonight and found an orphan black wire at the back. Contact with the frame and presto! - Brake & running & indicator & reverse lights work! I can't find its other end, which must come from the front, but this is obviously the common ground for the lights at the back end. Will invesigate in warmer (not 4F) weather. Your explanations and the 'black ground wire' helped me understand and find the problem. Only the licence plate lights have loose wires and it shouldn't take too long to find how they're wired in with the running lights.

Thanks again,

Gordon
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