scratching my head on this one - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

 3Likes
Reply
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 21 (permalink) Old Jul 10th, 19, 7:03 PM Thread Starter
Lifetime Premium Member
Eric
 
Join Date: May 2017
Location: Walden, NY
Posts: 640
scratching my head on this one

My Chevelle has been running great but tonight I went out and started it to see that the dash GEN light was on. Weird I thought because my car has a one wire alternator so I didn't even know that the light was functional. I checked the voltage at the battery and it was charging. 12.4 volts off and 14.3 when running. So I thought well I'll go anyway. Put the car (automatic) in reverse and it dies. Tried it a few times and the same, take it out of park and it dies. So the neutral safety switch must be playing a part. It's odd because the car was fine last time I drove it. Any ideas? I keep saying that I want to rewire the car because I don't know what's been done by others.
Dansk is offline  
Sponsored Links
Advertisement
 
post #2 of 21 (permalink) Old Jul 10th, 19, 7:30 PM
Lifetime Premium Member
Al
 
Join Date: Apr 2011
Location: SO CAL...Huntington Beach and Rancho Cucamonga
Posts: 5,059
Garage
Re: scratching my head on this one

Check your harness where the reg connector once was. I don't know what method they used to convert the one wire but a picture of that connector or what they did there would send me in the right direction. Check to see if the brown wire is shorting out the in that location. Also see if the brown wire is connected to anything. It's possible to wire the light to function on some one wire alts.

Are there any other wires connected to your alt besides the red charge wire?

Does the alt light go off when you shift out of neutral?

What year is your car?

The only time your neutral safety switch sees power is when you turn the ignition switch to the start position.
DUTCH MAX HEADWORK is offline  
post #3 of 21 (permalink) Old Jul 10th, 19, 7:43 PM
Lifetime Premium Member
Kim
 
Join Date: May 2017
Location: waayyy eastern Long Island
Posts: 522
Garage
Re: scratching my head on this one

I just had one that someone had run the charge wire through the horn relay, and all the power was coming back to the fuse block that way. Just something else to look at up in the left front.
shelteredv is online now  
 
post #4 of 21 (permalink) Old Jul 10th, 19, 8:03 PM
Lifetime Premium Member
Al
 
Join Date: Apr 2011
Location: SO CAL...Huntington Beach and Rancho Cucamonga
Posts: 5,059
Garage
Re: scratching my head on this one

YOU MIGHT BE IN A DANGEROUS POSITION AT THE MOMENT. SINCE I'M NOT SURE YOUR ELECTRICAL SYSTEM IS PROTECTED PROPERLY, YOU SHOULD BE READY TO DISCONNECT YOUR NEG BATTERY CABLE AT A MOMENTS NOTICE IF YOU SMELL BURNING INSULATION OR EXPECT A SHORT. HAVE A FIRE EXTINGUISHER ON HAND TOO, but disconnect the lead before fighting the fire if one occurs. Be aware that the battery could explode if the short is severe enough. I would probably loosen the clamp so the neg batt cable can be popped off easily if the need arises.

Your ignition circuit may be shorting out causing the engine to die.

I'm not sure what is going on yet, just want you to be forewarned.
Kirk's67SS likes this.
DUTCH MAX HEADWORK is offline  
post #5 of 21 (permalink) Old Jul 10th, 19, 8:57 PM Thread Starter
Lifetime Premium Member
Eric
 
Join Date: May 2017
Location: Walden, NY
Posts: 640
Re: scratching my head on this one

Thank you, I did disconnect the battery ground based on your advice. My car is a 66. The brown and red wire are just hanging on a connector next to the alternator. They could be plugged in to the excite terminals but aren't. The alternator is internally regulated based on the terminals orientation but they aren't used. There is no voltage regulator up near the horns and no wires there either. My alternator just has the battery wire and also a feed to the an HEI ignition relay from the same terminal. The ignition switch wire picks the relay and full battery voltage goes through the relay to the distributor. I've been scolded before for using a relay but my ignition switch has too much voltage drop for the HEI to run directly. I did replace the resistor wire but still don't get full voltage through the key switch.
Dansk is offline  
post #6 of 21 (permalink) Old Jul 10th, 19, 9:25 PM
Senior Tech Team
Eric
 
Join Date: Aug 2011
Location: Poteau, Ok
Posts: 4,155
Re: scratching my head on this one

I use a relay for my HEI, nothing wrong with that. Wiggle the key in the ignition switch and see if the light goes out once the car is running. Also start the engine in neutral and move the shifter to drive and see if the engine stalls. Then turn your idle screw up a bit and try again.
DUTCH MAX HEADWORK likes this.

Your just jealous because you can't hear the voices!

1967 Olds Cutlass 468 BBC/T400
1963 Plymouth Fury 440/Torqueflite
2007 Ford Mustang GT (momma's car)
oldcutlass is offline  
post #7 of 21 (permalink) Old Jul 10th, 19, 9:58 PM
Lifetime Premium Member
Al
 
Join Date: Apr 2011
Location: SO CAL...Huntington Beach and Rancho Cucamonga
Posts: 5,059
Garage
Re: scratching my head on this one

Quote:
Originally Posted by oldcutlass View Post
I use a relay for my HEI, nothing wrong with that. Wiggle the key in the ignition switch and see if the light goes out once the car is running. Also start the engine in neutral and move the shifter to drive and see if the engine stalls. Then turn your idle screw up a bit and try again.
Try this, we need to rule out a tuning issue before electrical. or,

You can also pull the HEI power plug and put a test light in the power terminal. Then turn on the ignition and put the shifter through the gears and see if you lose power or the light dims. Either would indicate a short, Return quickly to neutral and turn off the ignition. If you still have power to the HEI you have a tuning issue with the engine.

Sounds like One Wire Bubba got into your electrical system. It's probably a good time to consider a rewire with a reputable harness supplier.

If there is a short, the only time it occurs is with the ignition on and out of neutral. You have tried to go past reverse? Put it in drive ? If you have a Bubbafied electrical system without fuse protection a short in the backup light system could short out the ignition circuit while in reverse.

Unless I'm missing something, that brown wire has to be shorted to ground somewhere to get it to function.
DUTCH MAX HEADWORK is offline  
post #8 of 21 (permalink) Old Jul 11th, 19, 5:44 PM Thread Starter
Lifetime Premium Member
Eric
 
Join Date: May 2017
Location: Walden, NY
Posts: 640
Re: scratching my head on this one

I did quite a bit of probing after work today. It seems that I'm over due for a new harness. This particular issue is that there is 12.4 volts to the key switch but only three volts from there out to the fuse block. In probing around though I'm seeing low voltage in a lot of places down around 11 volts. It's obvious that someone re-wired under the hood but under the dash is original and somewhat butchered. I plan to go to American Autowire for a stock harness. I think they make a factory fit to work with HEI and a 12SI alternator. I'll also source a new GM ignition switch. Anything else that should be replaced after 53 years?
Dansk is offline  
post #9 of 21 (permalink) Old Jul 11th, 19, 7:15 PM
Lifetime Premium Member
Al
 
Join Date: Apr 2011
Location: SO CAL...Huntington Beach and Rancho Cucamonga
Posts: 5,059
Garage
Re: scratching my head on this one

Did you see in the stickies that there were wiring diagrams for your year? If you click on them you can download them without the watermark.

Head light switches seem to develop issues over the years so if you want to throw some cash around it may reduce problems in the future.

Your ignition switch might be bad. But the voltage drop may be caused from the short in the wiring somewhere. Disconnect the 2 brown wires( one solid brown and one brown with a white trace)) and see if your ignition voltages return to near batt voltage. The 2 brown wires lead out to the bulkhead connector where they join and continue out as a solid brown wire to the regulator. One is a resistance wire and the other leads to the gen bulb and then the bulkhead connector. If it's not hooked up to the reg or alt in someway, then there should be no continuity to ground or power on those wires at the switch when disconnected.
DUTCH MAX HEADWORK is offline  
post #10 of 21 (permalink) Old Jul 11th, 19, 8:32 PM Thread Starter
Lifetime Premium Member
Eric
 
Join Date: May 2017
Location: Walden, NY
Posts: 640
Re: scratching my head on this one

I think you are on to something. The brown wire runs out to my alternator but is not connected.(see photo) I checked and it is not shorted to gnd. in the engine compartment but when I reconnect the bulkhead it is 8.6 ohms to gnd so there is something going on under the dash. Can you pull the ignition switch without pulling the whole dash? It looks like it will be hard to access.
Attached Thumbnails
Click image for larger version

Name:	wiring.jpg
Views:	11
Size:	68.5 KB
ID:	598068  
Dansk is offline  
post #11 of 21 (permalink) Old Jul 11th, 19, 8:52 PM
Lifetime Premium Member
Al
 
Join Date: Apr 2011
Location: SO CAL...Huntington Beach and Rancho Cucamonga
Posts: 5,059
Garage
Re: scratching my head on this one

For the 66 gnition switcg you remove the tumbler from the switch first. Watch the video. Then unscrew the bezel and push the switch in. If you need pliers to get a grip. cover the jaws with elect tape so you don't damage the bezel. Disconnect the batt neg cable so nothing shorts out. You can hook it back up when it's clear of the dash for resting.

On your car the release holes should be on the right side of the key hole. The top hole will release the tumbler.


DUTCH MAX HEADWORK is offline  
post #12 of 21 (permalink) Old Jul 11th, 19, 9:04 PM
Lifetime Premium Member
Al
 
Join Date: Apr 2011
Location: SO CAL...Huntington Beach and Rancho Cucamonga
Posts: 5,059
Garage
Re: scratching my head on this one

Looks like it was set up for a 12SI before the one wire alt was installed. Without anything connected to that connector at the alt you should never get an alt warning light lit. So that's where I would look. The brown or brown wire with the tracer are shorting out somewhere. Disconnecting and taping off the connectors at both ends might isolate the short. But I would feel better to know that the short or issue has been located. No telling the extent of the issue or possible damage that can occur until you find the issue.
The warning light gets power from the ignition switch which is grounded at the alt when a no charge condition exists. As soon as the alt begins to charge the ground is interrupted and the light goes out.

If you get the switch out and disconnect the 2 brown wires and then see batt volts in the rest of your ign circuits you have found the culprit. Check your switch out puts to rule out faulty switch contacts or resistance in the switch.
DUTCH MAX HEADWORK is offline  
post #13 of 21 (permalink) Old Jul 11th, 19, 10:25 PM
Senior Tech Team
Eric
 
Join Date: Aug 2011
Location: Poteau, Ok
Posts: 4,155
Re: scratching my head on this one

The problem is the other brown wire from the ignition switch or the switch itself.

Your just jealous because you can't hear the voices!

1967 Olds Cutlass 468 BBC/T400
1963 Plymouth Fury 440/Torqueflite
2007 Ford Mustang GT (momma's car)
oldcutlass is offline  
post #14 of 21 (permalink) Old Jul 13th, 19, 2:20 PM Thread Starter
Lifetime Premium Member
Eric
 
Join Date: May 2017
Location: Walden, NY
Posts: 640
Re: scratching my head on this one

I took the ignition switch out and removed the brown wires. 12.1 volts to the ignition now so yes, the browns are the culprit. I then disconnected my battery and read ohms from the brown wire terminal that I removed from the ignition switch to gnd., it was 16 ohms. Tracing the schematic I see that the solid brown goes up to the fuse panel and feeds another solid brown that goes to the turn signal flasher. I removed the flasher and no change. I then followed the brown w/white trace wire. It goes up to the bulkhead connector. I disconnected the bulkhead and only a small change resulted. Remember that my brown wire under the hood goes nowhere so it shouldn't have had any affect. That same wire with the white trace also connects to a brown wire that feeds the generator indicator lamp. I removed that bulb and the resistance to gnd actually went down from 16 ohms to 8 ohms.
My next step was to check the fuse block. There was a wire attached to "Fused Accy" that powers my tach and transmission temperature gauge. I disconnected that wire and no change. Am I missing anything?
Dansk is offline  
post #15 of 21 (permalink) Old Jul 13th, 19, 4:13 PM
Lifetime Premium Member
Al
 
Join Date: Apr 2011
Location: SO CAL...Huntington Beach and Rancho Cucamonga
Posts: 5,059
Garage
Re: scratching my head on this one

have a funeral to go to so can't dig in now, hopefully someone can see the issue. I'll dig back in when I get back

Your resistance will change when you remove the bulb because it actually acts as the resistor in the wire. I could be wrong, but I think somewhere some how your brown wires are shorting to ground somewhere.
DUTCH MAX HEADWORK is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome