dibbons
Well-Known Member
I have low beam, but when pressing the floor switch for high beam the headlights go out and the ammeter goes to full discharge. I wonder where the first place to look would be? Thank you.
'65 Valiant No High Beam Problem
- Thread starter dibbons
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Bad dimmer switch, you may be able to take it apart and fix it. It's probably corroded up internally.
Just FYI, Rock Auto shows a listing for the switch.
Bad bulbs? Bad ground?
Usually a switch
dibbons
Well-Known Member
Update: I "borrowed" the working high beam switch from my '65 Barracuda and the same thing happened. In fact, not sure but I believe the low beams might have flickered off this time as well. I know I saw the ammeter go full overboard to the discharge side again. The turn signals, horn, and starter motor seem to work normally.
Then I removed the headlamp switch to find it was the NOS switch I had installed about a year ago. Still looks new on the outside. Time to think it over again.
With the ammeter acting up like that, I am hesitant to do much testing with the battery connected, don't want to burn/melt any wiring.
Then I removed the headlamp switch to find it was the NOS switch I had installed about a year ago. Still looks new on the outside. Time to think it over again.
With the ammeter acting up like that, I am hesitant to do much testing with the battery connected, don't want to burn/melt any wiring.
dibbons
Well-Known Member
I did purchase another NOS switch, in storage around here somewhere.
Big_John
In my defense, I was left unsupervised.
It's not the switch. If you think about it, the switch provides power to the dimmer. Nothing changes with the head light switch when you hit the dimmer. Look at the wiring diagram in your FSM and you'll see it's just one wire from the headlight switch to the dimmer.
You probably have a short somewhere in the wiring to the headlights. I'd trace the wiring back to the bulkhead and then from the bulkhead to the dimmer. You could also try unplugging the headlights and see it the ammeter still goes to discharge.
I'd also look at the grounds to the headlights, but I still think it's a short in the wiring.
dibbons
Well-Known Member
Update: With the headlamp switch disconnected and removed from the dash, I started the vehicle and ran it for 15 minutes. The ammeter worked fine (shows more charge at first then less charge), as well as the brake lights, horn, front and rear turn signals, dome light. My multimeter is on the blink, so I need to replace that first to track down any shorts (working alone).
67Dart273
Well-Known Member
Just to be clear, it COULD HAVE been the switch, AKA something broken inside, shorting against the case.
HOW TO TROUBLESHOOT A BAD SHORT. I've preached and preached this, nothing on the OP, but here's a good way and it's always worked. Obtain for yourself a junk tail/ stop lamp socket and if possible, heavy duty bulb, AKA 1157. If possible, salvage any old headlamp that works with at least one good filament. Wire one of these rigs IN SERIES with the battery neg to ground. This will protect your wiring, because all that will happen when a heavy load is energized OR A SHORT occurs, is that the series bulb will light bright.
You can wire a tail/ stop socket a few ways to obtain different wattages.
A....heaviest. Wire both pigtail wires together, use that for one terminal, and the socket shell for the other
B....Lighter: Use only the turn / stop filament pigtail and the shell
C....Lighter yet: Use only the tail filament and the shell
D....Even lighter: Leave the shell unconnected and use the two pigtails for the two lamp terminals. This places the filaments in series.
So far as "what's left," think about what you have, and what it is.
1...A short (length) harness from the dimmer switch which ends up feeding the low and hi beam wires out through the bulkhead connector. Possible. Maybe the wiring where it runs under the carpet and up the side got damaged and shorted.
2...Hi and lo feeds go through bulkhead connector, unlikely
3..Underhood harness, runs from bulkhead connector, around side of fender, and out rad support to healight. Examine this closely, something caught on sharp metal, abraided, etc.
4..The lamps. It would be rare, but a lamp COULD SHORT internally. They get hot, the internal structure is weakened by the heat, and years of thermal cycling. You maybe hit a bump, and part of the internal structure sagged a bit. Easy. Unplug the lamps and see if problem goes away
5...Probably least likely but tuck this away in case. At some point in the wiring, the high beam feed branches off to feed up to the hi beam indicator lamp. It is possible that this wire shorted somehow.
I don't remember the bulkhead connector/ wiring in the old girls. It MIGHT be possible that you can disconnect the lighting harness under the hood separately, from the bulkhead, and still have other power. If the short goes away and the hi beam indicator works, you'll know the problem is in that harness or the lamps/.
HOW TO TROUBLESHOOT A BAD SHORT. I've preached and preached this, nothing on the OP, but here's a good way and it's always worked. Obtain for yourself a junk tail/ stop lamp socket and if possible, heavy duty bulb, AKA 1157. If possible, salvage any old headlamp that works with at least one good filament. Wire one of these rigs IN SERIES with the battery neg to ground. This will protect your wiring, because all that will happen when a heavy load is energized OR A SHORT occurs, is that the series bulb will light bright.
You can wire a tail/ stop socket a few ways to obtain different wattages.
A....heaviest. Wire both pigtail wires together, use that for one terminal, and the socket shell for the other
B....Lighter: Use only the turn / stop filament pigtail and the shell
C....Lighter yet: Use only the tail filament and the shell
D....Even lighter: Leave the shell unconnected and use the two pigtails for the two lamp terminals. This places the filaments in series.
So far as "what's left," think about what you have, and what it is.
1...A short (length) harness from the dimmer switch which ends up feeding the low and hi beam wires out through the bulkhead connector. Possible. Maybe the wiring where it runs under the carpet and up the side got damaged and shorted.
2...Hi and lo feeds go through bulkhead connector, unlikely
3..Underhood harness, runs from bulkhead connector, around side of fender, and out rad support to healight. Examine this closely, something caught on sharp metal, abraided, etc.
4..The lamps. It would be rare, but a lamp COULD SHORT internally. They get hot, the internal structure is weakened by the heat, and years of thermal cycling. You maybe hit a bump, and part of the internal structure sagged a bit. Easy. Unplug the lamps and see if problem goes away
5...Probably least likely but tuck this away in case. At some point in the wiring, the high beam feed branches off to feed up to the hi beam indicator lamp. It is possible that this wire shorted somehow.
I don't remember the bulkhead connector/ wiring in the old girls. It MIGHT be possible that you can disconnect the lighting harness under the hood separately, from the bulkhead, and still have other power. If the short goes away and the hi beam indicator works, you'll know the problem is in that harness or the lamps/.
dibbons
Well-Known Member
Update: I decided to clean the headlamp ground wire connections before moving on. Dremel tool and mini brass brush on the headlamp bucket and Evaporust on the wire ends.
I found one headlamp was the newer halogen type, and the other was the conventional filament.
I found one headlamp was the newer halogen type, and the other was the conventional filament.
dibbons
Well-Known Member
Reader beware: This comparison I found online may or may not be accurate.
67Dart273
Well-Known Member
Find the short, then consider upgrades, AKA better headlights AND HEADLIGHT RELAYS and LARGER WIRE GAUGE
What you posted above is no where near causing the problem.
So you have the headlights disconnected. Did removing them remove the short?
What you posted above is no where near causing the problem.
So you have the headlights disconnected. Did removing them remove the short?
This is clearly some sort of serious short. You must find it.
Since it only occurs when the high beam is turned on, it is almost certainly in the wiring from the hi/lo switch to the headlamps. However...
Its highly unlikley that its in the headlight switch since it does not happen on low beam . The only point of concern is that the circuit breaker in the headlight switch should have opened as soon as the current exceeded 15 amps. The first thing I would check is every location where headlight harness goes through or next to metal edges. Headlight buckets for example got me (on my 67). Relays are a great help but do not prevent this sort of problem.
That appears to be roughly accurate although I beleive the author may have been using H6024 lamps. You would have to provide the details. Regardless, what @67Dart273 just posted is worth restating. a) Headlight relays are worthwile for several reasons. b) Its not revelant to the issue you need to diagnose.
Follow the route of your 1965 headlight circuit just like a map
When the ammeter goes discharge while the engine is running, that means the alternator can't provide the power but the battery can (albeit at 12 Volts not 14)
When the ammeter indicates maximum full discharge, that means something is drawing at least 35 or 40 amps. The alternator may or may not also be supplying power.
I would first suspect the high beam wire is chafing at the headlight buckets. If not there, look for other places it can chafe or get pinched.
When the ammeter goes discharge while the engine is running, that means the alternator can't provide the power but the battery can (albeit at 12 Volts not 14)
When the ammeter indicates maximum full discharge, that means something is drawing at least 35 or 40 amps. The alternator may or may not also be supplying power.
I would first suspect the high beam wire is chafing at the headlight buckets. If not there, look for other places it can chafe or get pinched.
Inertia
Well-Known Member
Did you scrutinize the floor switch plug ?
They often melt and may distort, perhaps unscrew and lift it from floor.
They often melt and may distort, perhaps unscrew and lift it from floor.
dibbons
Well-Known Member
See post #7. The first thing I did was substitute the floor dimmer switch from my other '65 Plymouth known to be working satisfactorily.
Inertia
Well-Known Member
I had read that, but just bringing attn to a melted plug, which could ground to switch body, so if removed from ground by screws . .
dibbons
Well-Known Member
With the headlights removed, same condition as before: high beam selection shows max ampere discharge on dash gauge.
Trace wiring back from HL connectors.
67Dart273
Well-Known Member
So then check the harness from the headlights back to the bulkhead (which I already mentioned). If you do not see anything,
Investigate if you can remove the section of the bulkhead connector supplying the headlight harness (which I also mentioned.) This will separate the problem from inside the pass compartment vs in the engine bay.
dibbons
Well-Known Member
Update: Underhood I found no defects in the area of the buckets. I did find a tiny bare metal chafing a couple on inches where it comes out of the bulkhead connector, but the bare spot was not touching anything (looks like it had become pinched somehow in the past). I put some tape on it (see photo) but same problem.
I disconnected the dash circuit board but left the two ammeter wires attached. Problem went away (see second photo)!
I disconnected the dash circuit board but left the two ammeter wires attached. Problem went away (see second photo)!
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