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Yup, no lights. None.

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Tremelune

Tremelune

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I just picked up a 1965 Austin-Healey Sprite...It's great, but there are no lights to speak of. None. Every other piece of electronics seems to be working fine--All dash gauges are working, car fires right up, battery does not drain over a week or two, starter is strong, fuel pump is whining.

The car has a generator with positive ground. The only aftermarket electronics I'm aware of is a stereo on a dash switch (works), and a Crane Cams XR700 Fireball electronic ignition.

I have an old Haynes with the wiring diagram, but I don't know where a lot of these components are on the car physically. I'm also having trouble seeing a single point of failure for all of the lights in the diagram (though it is very possible that I have more than one failing component anyway)...I'm working through it.

I found two (!) 35A (!) fuses, and both looked good, though both looked old. I'm inclined to replace them--indeed, I'm inclined to replace the whole fuse box with spade connectors--but I'd rather not monkey with anything that ain't broke. I don't think too much would work on the car if half or all of the fuses were blown...

I figured I'd chime in here sooner rather than later in case anyone was aware of likely suspects. One likely suspect I have is what I was told was the headlight switch on the dash--The wire running from it (RW) is cut. Looking under the dash, I can't see a corresponding cut wire, and this shouldn't effect the brake lights and blinkers (though I'm aware of the Prince of Darkness, so I guess anythings possible).

healey-light-switch.jpg
 
The top switch is headlights. 1 click down is parking lamps, 2 clicks is headlights.
The red/white wire is the dash lights, they are turned on by the bottom switch but will only work when the top switch is clicked on.
Check the switch, there is a heavy brown/blue wire on it, it should be hot all the time, the switch also should have a solid red wire 9parking lights)and a blue wire 9head lights) hook the brown to the red and see if the park lights come on, then try brown to blue for head lights.
You may also have a faulty dip switch, try jumping across the solid blue to blu/red and then blu/white for low or high beams.

As for signals and brake lights, check the fuse where the green wires are. It may be dirty, clean the fuse ends and fuse box with a scotch brite or steel wool but clean out any steel wool hairs.

Unless all the bulbs are blown and the grounds are bad, it has to be in the switch.
The headlights are not fused.

If the tach and fuel gauge work, they are on the same fuse as the brake lights and signals, check for a loose or dirty connection under the dash, right hand side where the rear sub harness meets the dash main harness. Those bullet connections need to be cleaned after about 40 years.
Same thing with the signal switch sub harness where it plugs into the dash harness under the steering column.
 
Looking more closely at the switch on the dash...There is a single R wire coming into the top (hot), a pair of RW wires coming off a single spade on the top, and the cut RW wire is coming off a spade on the bottom.

Looking at the diagram, I'm not sure how the switch on the dash could control any other lights but the dash lights...They RW wires only go to the four gauges, and the R wire just provides power...

I looked at the hydraulically activated (!) brake light switch as well as the flasher unit near the fuse box...I don't have my voltmeter with me, so I can't confirm whether or not they were getting power in the right places...I just eyeballed them...

The brakes are good, but not great. Could that contribute to the lights not coming on? I guess the first thing I'll need to do is bypass that switch and see if the tail lights light up...Actually, the first thing I should do is eyeball the bulbs.
 
If the fuses aren't blown, they aren't worn out. They're either good or bad. British 35 amp is about 17. There's a chart somewhere to show the conversion from Brit to American.

Your (our, I have a 66 with a Crane, positive ground as well) car has two fuses. The horn is one one by itself and everything else is on the other one.

There is a Brown with a Blue striped wire from A1 on the regulator to the light switch. If it's live, you should be able to jumper it to the red wire and have your running lights go on. All four should light up. Then jumper to the blue wire at the switch. Either your brights or your low beams should come on, assuming your running lights lit on the previous test. If not then the problem is as your dimmer switch, or beyond. Jumper at the dimmer switch from the blue to the blue/white then the blue/red. If they still didn't light, again assuming that the running lights came on for the first test, then the problem is your ground. Trace the Black wire from the right side headlight. ...
 
healey-light-switch-back.jpg

This is the back of the dash light switch (top of photo is top of switch).


healey-brake-light-switch.jpg

Here's the brake light switch by the front right wheel well.


healey-flasher.jpg

Some flasher for something near the fuse box...
 
Excellent info, guys, thanks. When I get a few more tools in my new place I'll give these ideas a shot. I expected this car to be weird, and it doesn't look like I'll be disappointed...
 
That switch is the dash light switch. (red red/white wires)
The TOP switch is the head light switch. Find the brown/blue wire, it powers the lights
 
Embarrassing update: As surmised, I was flipping the wrong switch. Every light works.


I bypassed the brake light switch and the brake lights lit up, but I don't think there's juice getting to the switch in the first place. I'm gonna trace that green wire, clean the relevant grounds, and see what happens.

Maybe one day I'll even have blinkers!
 
we all been there done that - keep us posted and we can talk you through most anything.
 
The ignition must be on for the brake lights to fire--With the ignition on, I get juice to the brake light switch, but no juice coming out when I press the pedal. The brakes work, so, I'm assuming it's that hydraulic switch.

Will I have to bleed the brake system to install a new switch? Even if I replace it, that thing seems likely to fail again in the future. Am I correct? Is there a way to hook up a simpler mechanical switch to the pedal?
 
no you won't have to bleed, and, there isn't a simpler arrangement. do you have a continuity tester? and a Voltage tester? if not, it is time to get them.

The brake switch is in the front of the housing for the brake and clutch pedal. you should be able to test the switch in place though the housing has to come off for you to replace it.

1. make sure the switch works with your continuity tester.

2. make sure you are getting 12 volts to the switch - I believe it is a green wire.

if the answer to both is yes, you need to start your way down the line.
 
the hydraulic brake light switch is easy to replace, and cheap. just get one that fits (3/8" IIRC) from NAPA. do it fast and you won't have to bleed the system, as fluid leaks out, but not air in. Check you master before and after, as it should be mere drops.
 
OK, maybe I'm wrong, brake light switch is easily removable on a square body Midget
 
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