67 327 electrical problem
Thread Starter
Instructor
Joined: Jan 2004
Posts: 104
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From: Redondo Beach CA
67 327 electrical problem
I just replaced the alternator, regulator, and starter motor. Wires are all on the correct terminals. I think I have a short somewhere. May or may not be related to the charging system. It may have existed before I replaced the components. When I turn the key to 'acc', with no load, the ammeter reads -20A. If I turn on a load (like the lights) in that position, the ammeter reads -40A or more. If I turn the key to the 'on' position, the ammeter reads -40A. The horn works with the key in the 'off' position. I think the relay is OK. To start the car I need a boost from a battery charger. It pins (-40A) the ammeter in start and then reads about +40A after starting and very slowly drops off to +5A as the engine runs. The engine starts well and is running very smooth. No smoke anywhere. I switched out the coil but no change. I charged the battery out of the car. Seems to take a full charge without indication of an internal short. It was reading about 14V after charge. Drops to about 12.3-13V as the engine runs. I am a bit suspicious of the battery. From the schematic that I have, it looks like the only components in the charging circuit are the battery, solenoid, ammeter, horn relay, ignition switch, voltage regulator and alternator + the harness. Has anyone seen this problem before?
Burning Brakes
Joined: Jan 2005
Posts: 768
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From: Leavenworth Washington
Disconnect and charge your battery so that it has a good charge to it. (I think your battery is fine). Measure the voltage of the battery out of the car. Pull all the fuses out of your fusebox and reconnect the battery. Check the voltage. If it's the same as it was before you connected it - good. Start replacing the fuses one by one and checking the voltage with the key in ACC. When you get the -20 indication and/or the voltage takes a drop - that's the circuit you have an issue with.
Let us know which one and am certain there will be some good help.
G
Let us know which one and am certain there will be some good help.
G
Thread Starter
Instructor
Joined: Jan 2004
Posts: 104
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From: Redondo Beach CA
Thanks. I actually did pull the fuses. I still had the problem. Actually, I noticed that when the headlights are on, the directionals do not work but they do work with the headlights are off. Also, the headlights work after I pulled all the fuses. The headlight fuse must be somewhere else. You are right about the battery. I connected another battery and had the same problem. There is a mysterious 20A load somewhere, maybe associated with the headlights. I will follow your procedure to see if I can isolate further. Would you know where the headlight fuse is located? JK
Thread Starter
Instructor
Joined: Jan 2004
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From: Redondo Beach CA
Disconnected the alternator. In 'acc' position the ammeter read -1 or -2 A. In 'on' position the ammeter read -25A. With switch off, and headlight on, -40A. Reconnected the alternator. Then I recharged the battery out of the car and measured 15.1V across the terminals. Pulled all the fuses in the fuse box. Installed the battery and measured 15.1V across the terminals. Turned switch to 'acc'. Ammeter read -20A. No change after replacing fuses one at a time. Ran the engine for about 15 minutes. Started without a boost. Same as before +40A slowly dropping to about +4A. I tried every load in the car. Everything worked correctly. As I turned on a load, the ammeter would flinch slightly toward discharge but always stay above zero. I also measured the voltage between the horn relay and regulator ground. 16V. The battery voltage with the engine off was 15.1V after running the car for 20 minutes. Absolute voltage measurements may not be what I read. Meter has not been calibrated for years. What do you think, alternator or regulator? They are new, not rebuilt.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
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From: New Hill NC
Those numbers are a little suspicious. There might be a problem with the Gage itself or its connections. They are not generally that lively.
And there appears to be a bad ground or socket on one of the bulbs causing the signals not to work.
I would be concerned about that 16V figure, if it is correct.
And there appears to be a bad ground or socket on one of the bulbs causing the signals not to work.
I would be concerned about that 16V figure, if it is correct.
Last edited by wombvette; Jul 12, 2011 at 10:11 PM.
Burning Brakes
Joined: Jan 2005
Posts: 768
Likes: 0
From: Leavenworth Washington
Those numbers are a little suspicious. There might be a problem with the Gage itself or its connections. They are not generally that lively.
And there appears to be a bad ground or socket on one of the bulbs causing the signals not to work.
I would be concerned about that 16V figure, if it is correct.
And there appears to be a bad ground or socket on one of the bulbs causing the signals not to work.
I would be concerned about that 16V figure, if it is correct.
Try pulling the turn signal flasher out. I don't have 67 wiring diagrams here - just 65 but my 65 flasher is electrically hooked direct (not through the fuses) to the ignition switch. Same for my wind shield washer and wiper motor so you might try disconnecting those as well to see if that takes out part of the mystery load.
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Thread Starter
Instructor
Joined: Jan 2004
Posts: 104
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From: Redondo Beach CA
This isn't just a gauge problem. The car is hard starting. I am only using the voltage numbers in a relative sense. I'll see if I can find a trusted voltage source to calibrate the meter tomorrow. I think I am going to put the old alternator back on first. The bearing failed, not an electrical problem. Without starting, I am going to try the same tests. The new alternator came from Ecklers. It looked a little funny to me, like someone had already put it on an engine. It looks like there was a grease stain on the paint. There may be a problem with this alternator. Back on line tomorrow with further info.
Le Mans Master
Joined: Nov 2000
Posts: 7,246
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From: Going too fast over the hill. Iowa
What do you think, alternator or regulator? They are new, not rebuilt.
There is a possibility that one of the harnesses has been fried. At some point, you need to get a $3 digital meter from Harbor Freight to be able to check your wiring.
For a harness by harness check;
Disconnect battery
Disconnect both bulkhead plugs (carefully) under the hood that are attached to the back of the fusebox.
Reconnect battery and check.
If the problem is gone, carefully reconnect one of the plugs to determine if the ignition or lamp plug wires have the fault
.
If the problem is not gone, disconnect the rear harness connector (under the dash).
If the problem is not gone, it's in the main dash harness or devices.
Otherwise it's in the rear harness.
Thread Starter
Instructor
Joined: Jan 2004
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From: Redondo Beach CA
Magicv8, If I pull the ignition harness connector at the firewall, how will I know that there is still a drop? Doesn't that remove the ignition switch and ammeter from the circuit? Suppose there was originally a short across the alternator leads (I am assuming some sort of alternator problem in addition to my original bearing problem), wouldn't the problem be in the ignition circuit. I notice some line resistors in several places in that harness. There seems to be 2 in the wiring near the voltage regulator and one in the wiring that runs along the firewall behind the distributor. Is it possible that I have a problem with one or more of these resistors due to a hypethetical short at the alternator? How would I test them. I could measure the resistance if I know what it should be. Also, it looks like maybe one was cut out of the harness, near the regulator. This would have happened before I got the car. Are they really needed?
Le Mans Master
Joined: Nov 2000
Posts: 7,246
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From: Going too fast over the hill. Iowa
I notice some line resistors in several places in that harness. There seems to be 2 in the wiring near the voltage regulator and one in the wiring that runs along the firewall behind the distributor. Is it possible that I have a problem with one or more of these resistors due to a hypethetical short at the alternator?
If you remove just the plug for the headlamps and parking lamps, you can test the engine harness and main dash harness together.
If you want to test the main dash harness by itself, you will need to connect it to the battery after the bulkhead plugs are pulled. The easiest way to make the battery connection is though a power supply plug in the cigar lighter socket or the accessory spade lugs in the lower right corner of the fuse box. The ports are for power windows and 4way flashers. If your car has both, you can disconnect one accessory and use the port
Last edited by magicv8; Jul 14, 2011 at 09:29 AM.
Thread Starter
Instructor
Joined: Jan 2004
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From: Redondo Beach CA
Magic, I guess what I called line resistors are really fusible links. Are they there to protect the harness in the event of an overload? Is it possible that one of these links is causing the problem? How about the ballast resistor that connects to the coil? Isn't that suppose to limit current? Could it fail "closed"?
Le Mans Master
Joined: Nov 2000
Posts: 7,246
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From: Going too fast over the hill. Iowa
Is it possible that one of these links is causing the problem?
How about the ballast resistor that connects to the coil? Isn't that suppose to limit current? Could it fail "closed"?
Thread Starter
Instructor
Joined: Jan 2004
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From: Redondo Beach CA
Magic, I am trying to understand a root cause of a failure in the harness that could be my problem. There are no dead shorts in any of the harnesses that I can detect. Sounds like if the fusible links didn't open but instead burned through to another wire, there would be a dead short at least when the switch was 'on'. I suppose a sneak circuit could also form pulling in an unexpected load. I am hypothesizing here. Is there a physical means of determining if a fusible link has 'let go'? Do they get soft and squishy? The ballast resistor seems to be out. The car has run for at least 1/2 hr. with this problem without the points burning out. Is there anything else in the ignition harness that could cause a phantom load? Also, if the car was operating normally, what should the current draw be across the ammeter with the switch in 'acc' and no loads (other than the clock). Is there current to excite the alternator field in this mode? With the switch in the 'on' position, what is the current draw? It there current for the alternator and for the coil primary? Is there anything else that gets mandatory power. I have some circuit schematics but they do not show voltages or currents at possible test points.
Le Mans Master
Joined: Nov 2000
Posts: 7,246
Likes: 21
From: Going too fast over the hill. Iowa
Sounds like if the fusible links didn't open but instead burned through to another wire, there would be a dead short at least when the switch was 'on'. I suppose a sneak circuit could also form pulling in an unexpected load. I am hypothesizing here. Is there a physical means of determining if a fusible link has 'let go'?
what should the current draw be across the ammeter with the switch in 'acc' and no loads (other than the clock). Is there current to excite the alternator field in this mode? With the switch in the 'on' position, what is the current draw? It there current for the alternator and for the coil primary? Is there anything else that gets mandatory power. I have some circuit schematics but they do not show voltages or currents at possible test points.
Red and orange wires are generally always hot (courtesy lamp, clock, glove compartment, brake switch, etc.).
IMO you need to find which harness is causing the problem before you can locate the source of the drain. Disconnect the LH bulkhead lamp harness and the rear harness. If the problem remains, disconnect the engine harness and power the dash harness to check if the problem remains.
Thread Starter
Instructor
Joined: Jan 2004
Posts: 104
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From: Redondo Beach CA
I pulled the light harness. Didn't seem to be a problem. I have inspected every inch of the ignition harness. I don't see how there could be a problem with it. I pulled the alternator and regulator. Didn't see a problem. I also ran the car. I seems to run perfectly normal except for the ammeter reading. I used the tester in my battery charger to check the alternator. It passed testing. Voltage across the battery was 12.7. Seems about right. I used every accessory in the car with no problem while the car was running. I am really at a loss here unless the problem is really the ammeter. I checked the current readings on another 67. They seem to be like mine but an order of magnitude less. It is like the scale of my ammeter suddenly changed. I would expect the ammeter to fail dead instead of changing scale factors. Anyway I am continuing testing tomorrow with another set of eyes. I really appreciate your knowledge. You have been quite helpful. Thanks.
Le Mans Master
Joined: Nov 2000
Posts: 7,246
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From: Going too fast over the hill. Iowa
It commonly failed in 63-66 Sting Rays when the (fat red wire) power connections burned, because the current to run the car would then be routed through the Battery Meter, which can't take more than about 2 or 3 amps. The failure mode was to burn a (usually repairable) hole in the meter winding, which froze the meter.
If your Battery Meter is at fault, the meter needle damping is shot.
Your 67 harness has fusible links protecting the meter. The rest of us have to add an inline 1 or 2 amp fuse to a meter terminal.
