MY ELECTRICAL HATES ME - REAR LIGHT POWER ISSUE

[playerpage]

I am going nuts. I have been chasing a wiring/grounding issue for two months now.

There is no power going to my rear lights as basic LIGHTS, but the flashers work and I have light when signaling a turn. The headlights work fine. I have tried to find out why, but am banging my head. Yes--the sockets are grounded. I have light for the turn signals, after all. There seems to be some problem getting power to flow down the brown wire back to the lights. I have pulled (and replaced) the headlight switch and tested it. There is no voltage reading on the brown wire when the lights are off, OR when they are on. If I simply leave the switch off and bridge the red wire and the brown wire, the rear lights come on! But I can't get it to happen with a brand new and obviously working switch. And if I turn the headlights on, and then bridge the wires, I still get the rear lights on but this time with a bit of sparking. I will restate--it can't be the dashboard switch, because I have three of them on hand and they all react the same way. My dashboard is grounded.

Another problem, and possibly related, is that there seems to be no power to the dash lights through the circuit that runs the fader. If I plug the dash lights into another circuit, they all go on, but I can't get them to run in the proper way.

Lastly, there seems to be a short in the running lights circuit, because only one light goes on when I pull on the single click that runs them.

Please help, he whimpered.

[bbodie52]

Your problem in your 1966 Corsa instrument panel might be a faulty ground.

The Corsa and Monza instrument panels can develop problems with the electric instruments and/or illumination lights. The panels are plastic, so a metal conductive grounding strap links the electric gauges together and then ties them to chassis ground at a single point. If the single screw that attaches that grounding strap to the metal dashboard becomes loose or corroded, the electrical ground to the instrument panel components may be lost and this can disrupt the operation of the electric gauges and illumination lights.





The sockets that hold the 1157 bulbs for turn signals/brake lights and the separate running lights circuit share a common ground, so the working turn signals/brakes tends to verify a proper grounding of the bulb sockets.

Do the front running lights work when you turn on the light switch?

At the rear, does the license plate light also fail to function? If you look at he schematic at the large multi-connector, you will see that the license plate light also gets its power from the same connector terminal as the running lights. Both are tied to the same multi-connector terminal. If no power is coming out of the multi-connector at that terminal, did you check the forward (firewall side) of the multi-connector to see if voltage is present at the input wire? If voltage is found at the input but is not coming out of the other side of the connector to feed the tail lights and the license plate light, the fault would likely be an internal bad connection between the metal pins in the two halves of the connector. You may need to separate the two halves and inspect the metal connectors. Look for a bent or deformed connector, or a corroded/burned connector. Cleaning and/or straightening the connector pins may solve the problem. The use of dielectric grease, as shown below, may also help to prevent dirty or corroded connector pins.

If voltage for the rear taillights is not present at the multi-connector input wire, the breakdown may be further forward at the instrument panel multi-connectors or at the light switch multi-connector. (The power for the front running lights (20 PPL) and the rear running lights (20 BRN) come from two separate light switch connector terminals, which you will see if you trace the circuit on the full schematic below). (Wire color codes may be different in the 1966 Corvair).

There is a large multi-connector in the Late Model engine compartment that can be a source of wiring problems. It is on the driver's side, below the voltage regulator. Even if the two halves of the plastic shell appear to be tightly pressed together, the metal connector pins inside can become deformed or corroded.






Left-click the image to enlarge it for better viewing or "Pan & Scan". Click a second time for maximum enlargement...

1965 Corvair Corsa Full Schematic

1965-1969 Corvair Engine Compartment Wiring Diagram (CORRECTED)



Dielectric-Tune-Up-Grease can sometimes improve the electrical connection in older metal connectors...

All rear circuits route through the engine compartment multi-connector (below the voltage regulator, near the firewall). The number of metal connector pins inside depend on the Corvair model year, ranging from 8-12 pins. This rear multi-connector is a common source of trouble, as it is subjected to age, vibration, heat, and moisture for many years. Even when the outer plastic shell halves appear to be tightly connected, the internal metal pins may not be providing good electrical connectivity, as they may be loose, dirty, corroded, or bent.

https://www.amazon.com/Permatex-22058-D ... ric+grease
Permatex 22058 Dielectric Tune-Up Grease, 3 oz. Tube

See CORVAIR COMBINED WIRING SCHEMATIC DIAGRAMS viewtopic.php?f=225&t=12968 for additional detailed wiring diagrams.

[joelsplace]

I think there is an orange wire that is power feeding the headlight switch for the running lights. I'm guessing no power on the orange wire so you can't get power out on the brown. The feed wire is B/OR in the above diagram. Black w/Orange stripe?

[playerpage]

Thanks Brad, Joel. (Hi Joel!)

I have spent hours on end printing and reprinting my schematic from the 1966 supplement, and then tracing things with colored pens. I know that the brown wire is most likely my problem, because when I do bridge my own power to it (through the main light switch multi-connector) every light that should come on, does. Yes, even the license plate light.

I thought, from what I could tell, the orange wire only powered the door jams and dome light, but I will look again. That is a clue I had not been given before.

Thank you Brad for the great overview of the many possibilities; I have tried most all of them, but I know you are answering not just for me, but for anyone else who may come across this thread in their own search--it was that kind of detail that drew me here in the first place. I have seen it in your other posts, and I was reminded of their value when I got frustrated again and some friends recommended I try you here.

In that spirit, I have my own PDF scans from the 1966 and 1967 Corvair electrical schematics that I can offer, but PDFs don't upload here, I guess. I often find that the 1965 is the most common one online, so I think these may be valuable to someone else. Is there somewhere I can send them?

I will report back regarding this adventure in wiring (that I once thought was over).

[joelsplace]

Actually your test tells you the brown wire isn't the problem. It is good all the way back since everything works when you put power to it.
We are assuming the switch is good since you tried 3.
That means the problem is in the power to the other side of the switch for the tail/license/marker lights.

[bbodie52]

In that spirit, I have my own PDF scans from the 1966 and 1967 Corvair electrical schematics that I can offer, but PDFs don't upload here, I guess. I often find that the 1965 is the most common one online, so I think these may be valuable to someone else. Is there somewhere I can send them?

Adobe Reader (.pdf) files can be uploaded and shared on the Corvair Forum. However, they are limited by a maximum file size. For example, the complete 1965 Corvair Chassis Shop Manual has a file size of 132,835 KB, which the Corvair forum operating system blocks because of the large file size (not because it is a .pdf file). But whenI broke the manual down into separate chapters, none of the individual chapters exceeded 20,000 KB. The largest chapter was 1965 Corvair Chassis Shop Manual - SECTION 6 - ENGINE, at 19,840 KB, which uploads to the Corvair Forum with no problem.

It is also possible to capture a page or a portion of a page, such as a schematic diagram, illustration, or a portion of a text displayed in Adobe Reader by using EDIT >> Take a Snapshot to capture the image to the Windows clipboard, and then paste that image into a photograph editor program like Corel PaintShop Pro or another application like Microsoft Word or Microsoft PowerPoint. From there the image(s) can be saved in many formats, including Word documents, JPEG image files, etc. The three pages of Shop Manual schematics were captured in this way, and pasted into PowerPoint for editing and grouping into a single large schematic, and then saved as a JPEG image file for enlarged viewing and scanning on the Corvair Forum.

You can send someone an email with a large .pdf file attachment, but if you plan on uploading a .pdf file on the Corvair Forum, the file size must be small enough to be accepted by the website software. Most captured images that are save as photo images, such as JPEG (.jpg) images, are small enough to be directly uploaded as attachments to a post.

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...from what I could tell, the orange wire only powered the door jams and dome light, but I will look again. That is a clue I had not been given before...

There appear to be two power feeds to the light switch. The primary feed is an unswitched/unfused (14R RED) wire that is distributed to the headlight circuits and lighting circuits that work even with the ignition key OFF. Some light circuits only function with the key ON. Those may be powered by the fused power wire (20 B/OR) that originates at the fuse block.

...I have spent hours on end printing and reprinting my schematic from the 1966 supplement, and then tracing things with colored pens. I know that the brown wire is most likely my problem, because when I do bridge my own power to it (through the main light switch multi-connector) every light that should come on, does. Yes, even the license plate light...

If you are getting functional tail light and license plate lights by connecting a temporary voltage source to the brown wire at the main light switch, you are proving the functionality of the brown wire circuit throughout the vehicle. Is voltage present at the associated pin output from the light switch (or is there electrical continuity from the RED input terminal to the BROWN output terminal at the light switch with the switch ON? If the switch is new and/or tests good with an OHM RESISTANCE test from the RED to the BROWN terminal, and the brown wire tests good from the connector to the bulbs, then perhaps the failure point is between the old electrical connector and the light switch when you plug the two together. The connector may be faulty.

[playerpage]

Success!! Many thanks Joel and Brad for your clues, and thank you to Craig Niccol for walking me through fixing it over the phone. It was indeed the orange wire. That little devil splits into about six different directions, and the end that was plugged into the CLOCK was shorting inside the clock's broken mechanism before going into the rear lights. After unplugging the clock, everything works now.

Cheers!

[bbodie52]

Amazing!!

That is the first time I've heard a story about the clock shorting and causing failure in another circuit as you described.

[playerpage]

I've cataloged a lot of firsts in my life. Everything from Corvair issues to student loans to the plumbing to phone service to the wiring in my house. More often than not, I call up some customer service rep or get a technician over to the house, only to hear that familiar low whistle along with the comment, "That never happens. I've never seen that before."

I'm just happy it got worked out. Thanks again!