[421safari]

So, I finally have the wagon roadworthy & inspected again after far too long..

However, I noticed the rheostat for the instrument lighting was iffy and I had some flicker on the headlights when I used the high beams a couple of days ago (switched them off right away again and flicker stopped, test sample of 1)

As I still had a new headlight switch and I have had them fail at inconvenient times before, I thought to be ahead this once and replace the current one to be safe and hopefully solve the instrument lighting being too iffy as well.

So far the good idea.. Now the bad result, front lights stopped working.

I thought maybe the new switch wasn't ok, so I switched the old one back. Alas, no dice (or lights).

(Note that the new switch had one extra contact tab, but that was located in a spot where my connector does not have a wire. For all other intents & purposes it looks the same.)

I have checked all fuses in the main fuse box leftside under the dash and they are all fine. (which fuse is for the headlamps anyway? could not find that out from the manual)

• The taillights function fine, as do the directional lights, the hazards and the brake lights.
• Parking light front (headlight switch halfway out) is fine (small light in top lights).
• Neither lowbeam nor highbeam is working
• Using highbeam switch has no effect at all, not even the red 'chief' indicator in the speedo lights.

I cannot remember for certain, but I *think* I already used the high beam foot switch *before* checking the head lights with the new switch in.

What would be the most likely problem? faulty highbeam foot switch? How can I check that without having to remove/damage the carpet?

Having no head lights is quite inconvenient, especially as I wanted to take it out this evening to get my take-out dinner

[Stuart]

My guess is the foot switch is faulty or has a bad connection, it's happened to me. Since they are on the floor they can be exposed to moisture and then of course the connections can corrode.

You will have to lift up the corner of the carpet to get to it. Hopefully, the connections just need cleaning but if the switch is bad you may be able to use jumper wires to bypass it temporarily.

[421safari]

I just checked the dimmer switch. Disconnected the plug:

The resistance fluctuated a little bit (probably due the contact with the test leads) but the switch had continuity on both settings (from blue to brown/tan and from blue to green).

Jumpered both blue to green and blue to tan: nothing. No lights.

So maybe not the dimmer switch? but then what?

[66 Wagon]

Yes, I'd would also check the dimmer switch. Could be the headlight switch too. There are no fuses for the headlights.
Another thing to avoid future problems with the headlights is to add relays. This to avoid overheating the headlight switch and dimmer switch and that will also add fuses for the headlights, wheter you use the original sealed beams or do a H4/H1 conversion

[pfilean]

The problem with the dash lights and problem with headlights Probably have nothing to do with each other. Except that it is all old corroded electronics.

Dash light problem would be the rheostat which do get old and do not make good contact. Is a definite inconvenience but not likely to blow anything up. But as you had a new switch on the shelf why not change. Should have solved that problem but it sounds like you have since been to busy with the headlights to notice if the dash lights are good or not.

As for the headlights I think Stuart may be on the right track as pushing the dimmer caused some unusual results. You say the headlight fuse is good but it may need another look. The fuse panel is usually marked as to which fuse is which. But age deteriorates the lettering and besides they are hard to see even if you are young and able to screw yourself under the dash to look. But these cars are not usually owned by 18 year olds (no offense intended). Exactly what year are you dealing with? We can probably come up with some description of the panel.

[421safari]

It's a '66 bonneville wagon. The fuse box lettering is quite crisp still and seems to perfectly match the indications in the shop manual (page 12-12).

going from left top to bottom:

• 14A Spot lamp & underhood lamp
• 14A Glove box, dome, all courtesy, luggage compt, cigar lighter, clock
• 4A instr.panel & rheo controlled lights

right top to bottom:

• 9A Radio
• 14A Stop & dir. sigs.
• 25A wiper & backup lamps
• 20A HEATER, AC Master Control, Park brake warn, power ant, speedo & defogger
• 14A tail lights & ign sw light

What I find strange is that ALL head lights have stopped working. If the problem was the new switch, re-installing the old one should have fixed that. If it was the dimmer switch, jumpering the plug should have produced something (even if the connection wasn't that great). I cannot imagine how all lamps would have burned out simultaneously from the new switch, even if it was faulty.

So, assuming the lamps themselves are still ok where do they have a common point aside from headlight switch and dimmer switch?

A fuse seems logical, but again the ones in the fuse box seem fine. Still, which of the ones above would be the one the headlights are on?

Page 12-48 of the shop manual lists all fuse values for all applications. It mentions a "Lighting switch circuit breaker". Would this be internally to the headlight switch?

(installing relays are definitely on the TO-DO list for this car, just not tonight )

[421safari]

here are pictures of both old and new switch

old switch

new switch

The new switch's box was hand marked 'E14508'. *Think* it came from Ames, but not sure.

[cheese country GP]

circuit breaker is in the headlight switch. had this same problem in a '63 ford wagon & was bad wiring to & from the dimmer switch.

[66 Wagon]

There are no fuses for the headlights, just a circuit brekaer in the panel light switch. It's a bit hard for me to explain, I'm not that good in English but when the curcuit breaker gets overheated it shuts off the lights. It propably is broken. Check all the wires and replace the switch if necessary and add relays to the headlights. By that the power from the battery to the headlamps doesn't take the long route via the switch on the dashboard, instead the power goes the 30 centimeters from the battery direct to the headlamps and just a wire to control the relays goes to the light switch.

[421safari]

Thanks, your explanation is perfectly understandable! I understand about the relays. Just want to get it fixed in its current state, relays later. Depending on what exactly the problem is, adding relays may not solve it right now.

ok, so let's sum up:

• the lamps themselves are fine (highly unlikely for them to go/burn simultaneously)
• the dimmer switch is fine/not the cause (jumpering had no effect)
• the old headlight switch is fine/not the cause (low beams working fine before swapping)
• no fuse for the headlights, all fuses are fine

As far as I can see from the wiring diagrams the only parts affecting both high & low beams at this point is the wire between the head light switch and the dimmer switch (light blue) and the +12 wire (red unfused) going into the head light switch.

Maybe by rummaging under the dash and pulling on the plug one of those does not make contact anymore. I can't really make heads or tails of the schematic of the inside of the head light switch though. From the wiring diagram:

1. White - dome light: grounds bulb in switch, other bulb contact goes to fuse box. No power from red +12.

2. Red: unfused +12 from battery.

3. Grey - instrument lighting: goes from switch to bulbs to ground, since it is fused (left lower 4A fuse) it cannot derive power from red +12.

4. Green - ign. lamp: this one I don't understand as it is both connected to fuse and bulb going to ground. Not sure what happens there, but seems highly unlikely it is somehow also connected to red +12.

5. Blue - Front beams: takes power from red +12.

6. Brown/White: goes to taillight fuse. no connection possible to unfused red +12.

7. Purple - Parking lights: goes from switch to bulbs to ground, probably fused? If so, no power from red +12.

8. Brown - Taillights: goes from switch to bulbs to ground, since it is fused (right lower 14A fuse) it cannot derive power from red +12.

Meaning red +12 should only be used for front beams. That probably means either the red or the blue wire is not making a proper contact at the switch. Will check tomorrow.

On a sidenote: the shop manual I have shows seven wires connected to head light switch. The schematic I have from www.classiccarwiring.com shows eight wires. In the shop manual there seems to be no wire going to the taillights, which is the #8 wire in the other schematic.

The old head light switch has 8 tabs, the new one had only seven. I still put it in as the plug also only had seven wires. Maybe one wire has come out of the plug though. How many wires should the head light switch plug have?

[421safari]

checked this morning and after some fiddling and measuring all lights work again. Probably either one of those red or blue wires has a less than ideal contact. The contact resistances are pretty high as well, at the dimmer switch there is only about 10.5Volts left, from the 11.5V (engine off) going into the head light switch. And the dimmer switch is bad, immediate flickering on the high beams with the circuit breaker in the head light switch opening and closing. The head light switch was _hot_ within less than a minute.

So I am going to replace both dimmer and headlight switch just to be sure and use relays as soon as possible to keep them healthy. I want to ask if anybody knows a kit or partial kit so I don't have to fabricate everything, but I first need to check the connector at the lights as I already have E-code lights (necessary for import approval here)

I also took a look at the wires but my plug definitely only has 7 wires going into the switch. The one that is missing is the #8 brown wire (which isn't in the shop manual, so that means the manual is correct). Curious how the tail lights get switched then. The replacement switch I have with 7 tabs is still incorrect though as it misses the tab for the parking lights, one of the other tabs goes unused.

[421safari]

Hmm, both rockauto and Ames no longer carry the head light switch for '66. Looking on ebay I see a lot of switches that look 100% identical but all say they are not suited for 1966 pontiac bonneville. So they are probably different internally?

The manual lists 1995138 as the part number for the switch. Is there a replacement part number that is still current, or are used/nos ones the only options left?

[66 Wagon]

Here's a cheap relay kit you can use: http://www.ebay.com/itm/H4-Headlight-Headlamp-H4-Light-Bulbs-Relay-Wiring-Harness-4-Ceramic-Socket-Plug/232125265635[/B]

The E-cdoded headlights you use can be why you're having trouble. The original sealed beams was 35 watts each, the E-coded lights are 55/60 watts and makes the wires and switches hot

[421safari]

thanks, that's a very good point, had not realised that yet.

The low beams work, but even then the switch gets very hot to the touch within minutes.

That set looks pretty much plug and play but as I was planning to take the wagon on a trip next week it probably wouldn't have been delivered quick enough. Also on many of those kits it is unclear what wire gauge is being used, and the few ones that did indicate it I found to be using a little too thin wires for my taste. If you're going to put in new wires at least give them some headroom..

I ordered all parts locally to make a similar harness this weekend without needing any modification of the original harness. I'll even try to get the wires somewhat color correct

[RAM YAK II]

Have you checked the grounds yet? They should be removed and cleaned. Don't forget to clean the sheetmetal where the screw and terminal meet. You'd be surprized how many of the symptons you are having are similar to a bad ground. Won't take but a minute to check. Short black wires leading from the headlight connector to the radiator support (on a '62 Catalina).

[421safari]

grounds could probably use some cleaning up but are fairly decent (around 1 ohm resistance). My original problem has resolved itself in that the lights started working again at some point (before adding relays). I suspect either or both the head light or dimmer switch is bad, likely caused by the E-code head lights drawing too much current.

Even though I have now added relays for low- and high beams, my head light switch still gets fairly hot to the touch. Not freakishly hot like before, but still warm-to-hot. Even though the only thing drawing current is the relays..

So, I'll be replacing both the head light and the dimmer switch and see what is the temperature then.