65 Impala SS same ole electrical problem but - Impala Tech
Electrical & Wiring Troubleshooting electrical problems

 
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post #1 of 10 (permalink) Old 01-22-2016, 01:24 AM Thread Starter
 
 
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65 Impala SS same ole electrical problem but

I just have one question, for now, is there suppose to be constant power 12.3v to the right side of the "tail lps" fuse connector, when there is no fuse in place with the key off? I even disconnected the brake switch and still have power there, so before I dig more that way I need to know if it suppose to be that way. Of course the prob is no tail no brake no nothing and the fuse pops as soon as I put it in. So there is a short somewhere most likely a ground problem. Anyone ? Thank you.
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post #2 of 10 (permalink) Old 01-22-2016, 10:05 AM
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According to this wiring diagram (I suggest you have this printed out at Kinko's or some other place that has a large D size paper printer/plotter) it is powered by the ignition switch so it shouldn't be hot.

http://fatchance-hotrods.co.uk/image...%20diagram.jpg

Big Dave
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post #3 of 10 (permalink) Old 01-22-2016, 08:21 PM Thread Starter
 
 
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I admit, electrical is my weak point. The part I'm not getting is the fuse Box. I see it on there but not sure how to read it, I mean there 7 fuses , with wires on each end, it doesn't really correlate with schematic, do you mind helping me out? Turn it sideways? What color wire is the one going to the Tail LPS right side? Would it be the third one down on the right? Gray wire that goes to the Ign light? I've looked for this subject online and all I see are newer schematics that they teach from that don't look very much like our 65-66. I've built my car from the ground up pretty much, but this has me stumped. So fuse box, then rectangles that look like Dominos? Is that the engine side of the fuse box? Do you mind?
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post #4 of 10 (permalink) Old 01-23-2016, 10:51 AM
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The brown wire goes from the fuse box to power the light switch. The light blue to gray wire (depending upon your screen settings) goes from the ignition switch to power those fuses that are shown in the fuse box illustration (the rest of the fuses not listed are hot all of the time such as the horn and brake lights). These colors by the way are false colors to make reading the diagram easier. they are not the color codes used by GM to mark their wiring.

You need to look in the wiring diagram supplement sold separately from the Service manual for a full ANSI D size print (22 inches by 34 inches sheet of paper). These pages are printed in black and white but they show every color code of every wire and where it is connected.

In the Assembly manual you can see how the wiring harnesses are connected at their termination points and in the Fisher body manual how the wiring harnesses are routed about the car's body. A wiring diagram doesn't represent the actual routing or bundling of wires but is a simple schematic of the circuits. GM's wiring diagrams differ from NEMA (National Electrical Manufacturers Association) electrical wiring diagram symbols by showing a pictogram of the actual device (such as the distributor or a head lamp) to make comprehension easier to understand. They also do not jump wires to distinguish where they are connected or just crossing (which can be potentially confusing if tracing a circuit). Usually a junction is shown by a dot where the wires cross.

If you get tired of replacing fuses and do not wish to break down on the side of the road due to an intermittent electrical short you can replace your fuses with same Amperage rating circuit breakers. They will automatically reset when they cool off if a circuit shorts and draws more than the rated current.

These Buss Circuit Breakers replace your existing glass fuse:



In trouble shooting I use a six gauge wire with a battery clamp on one end attached to the negative terminal of the battery and a small alligator clip on the other end to test for bad grounds. To energize a circuit I used to use a similar twenty five foot long six gauge wire with a sharp probe that could pierce a wire's insulation before I bought a Power Probe III PP3LS01 Circuit Tester. Considering the tool costs nearly half as much as a whole new wiring harness from AAW (American Auto Wire) I can't recommend it for one time use. If you plan on buying more than one old car though; it's value increases.

Big Dave
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post #5 of 10 (permalink) Old 01-23-2016, 12:17 PM
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I going to try and help you out doing this logically.
The question is, Did they work before? What have you done to the car recently? Using a ohm meter will show a short unless you remove all the bulbs to open the circuit.

So, The orange wire from the fuse box is constant "hot" and feeds the following; Courtesy lights, Headlights, Trunk light (if you have one), Stop lights, and finally the Glove box light (if you have one).

With the fuse popping as soon as you put it in, there is definitely a short. You say you have disconnected the brake light switch and it still blows. Leave this disconnected. This will eliminate that circuit.

Next, disconnect the courtesy light connector, this is on the driver side under the dash. It will have both a white and a orange wire. Leave it disconnected, for the time being. Replace the fuse and see if it blows. If it does...then we'll move on. If not, your short is in that circuit.

Next disconnect the glove box light, there should be a single connector with an orange wire to the left of the glove box, just follow the wire from the light, and disconnect. Replace the fuse and see if it blows. If it does, we move on. If not, your short is in that circuit.

Pull back the carpet on the driver side floor and disconnect the ribbon strip wire. This goes to the rear lights and trunk light. Replace the fuse and see if it blows. If it does, we move on. If not, your short is in that circuit.

If after disconnecting those three connectors, and replacing the fuse and it still blows...You have a short in the main dash harness. Look for any pinched sections of the harness or anything that has been screwed into the harness or has rubbed (chafed) through the harness. Once you find the short and fix it, you can reconnect the previously disconnected connectors, one at a time watching for the fuse to blow.

Hope this helps.

Chris

Chris
Warrenton, OR
'68 CJ-5 - Sold
'74 Nova
'10 Camaro
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post #6 of 10 (permalink) Old 01-24-2016, 12:13 AM Thread Starter
 
 
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Well today I replaced all the rear sockets, the headlight switch, checked the dome lights, the brake switch. all my interior lights are working except the dash. The fuse is fine, until I turn on the headlights, then it blows. I took the fuse block off and took note of all the wires. The wire on the right side of the fuse for the tail lps (the one thats blowing) is red. I assume that is the power so it is probably suppose to be hot at all time. The left side is Black and orange. So I am going to start following the black/orange wire and see if I can find the prob. I have had the car apart for a year, rebuilt all the mechanicals, its a street/strip car so I have added new Dart 548 engine, new trans, new rearend. All new MSD ignition, electric fan, toggle panel 6 switches w/ignition. The car runs fine, starts fine. So it could be anything. I like your idea, I sort have done that along the way but I can do it a little more methodically. Thank you and Big Dave for your help.
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post #7 of 10 (permalink) Old 01-24-2016, 12:24 AM Thread Starter
 
 
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Also I have the service manual and the assembly manual. Now that I know which wires are at the box, I think I may be able to read the schematics, hopefully. Anyone live in SoCal?
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post #8 of 10 (permalink) Old 01-24-2016, 10:20 AM
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Quote:
Originally Posted by 65Dan View Post
Well today I replaced all the rear sockets, the headlight switch, checked the dome lights, the brake switch. all my interior lights are working except the dash. The fuse is fine, until I turn on the headlights, then it blows. I took the fuse block off and took note of all the wires. The wire on the right side of the fuse for the tail lps (the one thats blowing) is red. I assume that is the power so it is probably suppose to be hot at all time. The left side is Black and orange. So I am going to start following the black/orange wire and see if I can find the prob. I have had the car apart for a year, rebuilt all the mechanicals, its a street/strip car so I have added new Dart 548 engine, new trans, new rearend. All new MSD ignition, electric fan, toggle panel 6 switches w/ignition. The car runs fine, starts fine. So it could be anything. I like your idea, I sort have done that along the way but I can do it a little more methodically. Thank you and Big Dave for your help.
Now that you have narrowed it down to the tail lights, unplug the ribbon wire behind the brake pedal on the floor. If it blows, look from the connector back to the light switch. If all is good, then unplug the ribbon wire under the package tray in the trunk, driver side, from the tail light harness and reconnect the ribbon wire on the front floor. If it blows, you may have pinched the ribbon wire at some point. If all is good at that point, you have a short in the tail light wiring harness. There's is no grounds in this harness. Everything is grounded through the tail light bezels. Also, look for wire chaffing.

Chris

Chris
Warrenton, OR
'68 CJ-5 - Sold
'74 Nova
'10 Camaro

Last edited by jayhawk500; 01-24-2016 at 01:37 PM.
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post #9 of 10 (permalink) Old 01-28-2016, 02:02 PM Thread Starter
 
 
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Smile

Success. After climbing all over my baby, I isolated one of my issues to the brown wire that runs through the ribbon in the cab to the trunk. Unfortunately I have laid down dynamat and rear carpet. So I removed the wire on both ends and ran a wire above the dynamat, along the sill to the trunk. Soldered it back in line in the trunk. So that fixed a couple things but I still had brake lights constant. I had already replaced the brake switch, but the brake pedal arm that pushes in the plunger to activate the lights wasn't pushing it in far enough. I found out it had to press it ALL the way in to turn the brakes lights off. So that was fixed. Then I had one more issue my drivers courtesy light had a wire the was mostly broken in the socket, took it out, soldered it in, discovered there was an extra black and white wire connected to the courtesy light, I removed it. Everything seems to be back in shape, all lights exterior and interior are working properly. Not sure about the extra wire I'll figure it out later or as I go. Now I can concentrate and getting it back on the road. 95% there. Thanks again.
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post #10 of 10 (permalink) Old 01-28-2016, 04:59 PM
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Quote:
Originally Posted by 65Dan View Post
Success. After climbing all over my baby, I isolated one of my issues to the brown wire that runs through the ribbon in the cab to the trunk. Unfortunately I have laid down dynamat and rear carpet. So I removed the wire on both ends and ran a wire above the dynamat, along the sill to the trunk. Soldered it back in line in the trunk. So that fixed a couple things but I still had brake lights constant. I had already replaced the brake switch, but the brake pedal arm that pushes in the plunger to activate the lights wasn't pushing it in far enough. I found out it had to press it ALL the way in to turn the brakes lights off. So that was fixed. Then I had one more issue my drivers courtesy light had a wire the was mostly broken in the socket, took it out, soldered it in, discovered there was an extra black and white wire connected to the courtesy light, I removed it. Everything seems to be back in shape, all lights exterior and interior are working properly. Not sure about the extra wire I'll figure it out later or as I go. Now I can concentrate and getting it back on the road. 95% there. Thanks again.

Your Welcome, Hope my information was helpful.

Chris

Chris
Warrenton, OR
'68 CJ-5 - Sold
'74 Nova
'10 Camaro
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