Charging System Troubleshooting--Blown Ignition Light Fuse?

[patrickt]

Originally Posted by DanEC

Wish I could help more on the root issue but Patricks on the case so he will get it figured out - I have confidence in him.

Wait 'til he sees my bill.

[ACHiPo]

Originally Posted by patrickt

Yes, because you want to get the car running and charging normally first, and then search for the short on the line you've eliminated. If running a fresh, clean, fused 12v+ line to the ignition light makes the light come on, and then go out after the car starts charging (because the current through that ignition light excites the VR in to working), then you just move on to finding the short on the eliminated line. That will not be hard to do.

Patrick,
Thanks. Ran out of daylight (and positivity) yesterday, so took a break. I'm talking to Bob this morning. Since I've eliminated the VR, alt, tach, and fuel gauge from previous testing, it seems to me it's got to be the heater or wiper circuit. Will post what I find out and next steps.

Evan

Originally Posted by patrickt

Wait 'til he sees my bill.

PS put it on my tab

[ACHiPo]

Originally Posted by DanEC

Evan - you can remove the steering wheel, loosen the brackets holding the steering column to lower it as much as possible, wrap the column to protect the finish, and remove the screws holding the panel and lower it to where the column will support it. Just don't completely unscrew the column bracket - lower it as much as possible. There are so many cables, wires, etc connected to it that it won't go anywhere. Then as Patrick said you can access it from the top.

Wish I could help more on the root issue but Patricks on the case so he will get it figured out - I have confidence in him.

On the broken visor - don't sweat it - gives you a reason to order those from Finish Line with the gold Cobra label like the originals.

Dan,
I was able to drop the dash about 3/4" which actually made a huge difference in being able to fit my hand up behind the fuel gauge so I got the gauge put back together. I was not able to get the two dashboard end screws (behind the doors) started and gave up before I hurt the car or me. Will also check with ERA on tips to get the dash into just the right position to get those screws started.

Unfortunately the visor that broke was from Finish Line with the gold engraving. Replacement and a spare are ordered. That was easy enough.
Evan

[patrickt]

Here, this test will take less than five minutes, requires no wire cutting and, if successful, will make your car drivable (excluding wipers, gauges, and heater).

[ACHiPo]

Pat,
This looks great! Talking to Bob I checked the ignition light for short to ground, but it's good. He suggested I try to duplicate a symptom I noticed Friday next--with the fan unplugged and car running, the ammeter swung positive when the fan relay was energized.

After that I was going to start checking for shorts to ground at the fuse box, then into the loom at this point, but will give your idea a try first. It will likely be tomorrow evening before I get a chance.

Evan

[patrickt]

And if that test is successful, then the quick way to find the short would be to invest in a short and open finder tool. You can get fancy ones, or there's a couple on Amazon for less than $30. Like this: https://www.amazon.com/allsun-Automo.../dp/B07BC4X28Y

[ACHiPo]

Originally Posted by patrickt

Here, this test will take less than five minutes, requires no wire cutting and, if successful, will make your car drivable (excluding wipers, gauges, and heater).

I got a chance to try Patrick's diagnostic, and I got something, but not what I hoped for.

Removed the ignition light from the dash for access. Pulled the double green wire off the ground spade of the light socket. Ran a fused jumper between the accessory terminal on the ignition to the grounded lug of the ignition light.

Turned key to ON position. No light.
Started engine and light came on while cranking and extinguished when engine started.
Ammeter was slightly negative (~1A) with engine running. Turned on headlights and ammeter dropped to ~-12A. Revved engine, but ammeter didn't budge.

I'm sure I learned something, just not sure what. Maybe that I can definitely eliminate the gauges as a short path?

[patrickt]

That's progress. For the next set of tests, you will leave the double green wire disconnectied from the light for everything below.

1) Remove the G/R wire from the ignition light but leave your fused jumper wire running to the light. Turn the ignition switch ON but do not start the car. Touch a known good ground lead to the exposed pin of the light and observe that it illuminates. Then, using a VOM, test for either a) 12v+, b) 12v-, or c) neither one at all at the disconnected G/R wire. Report the findings.

2) Plug the G/R wire back on to the ignition light. With the ignition ON, and the car not running, the light should be "ON" but you report that it is not. Try running a known good ground wire to the alternator and voltage regulator and touch different spots on both those components just to see if you can get the ignition light to illuminate. For instance, touching a known good ground wire to the VR case and making the light come on each time you did that would be a really nice sign. Report back.

3) Insert a fuse in to Fuse #3 and turn the key ON, but do not start the car. See if your gauges, heater, and wipers work or if you blow the fuse doing that. Report back.

We are making progress.

[ACHiPo]

Originally Posted by patrickt

That's progress. For the next set of tests, you will leave the double green wire disconnectied from the light for everything below.

1) Remove the G/R wire from the ignition light but leave your fused jumper wire running to the light. Turn the ignition switch ON but do not start the car. Touch a known good ground lead to the exposed pin of the light and observe that it illuminates. Then, using a VOM, test for either a) 12v+, b) 12v-, or c) neither one at all at the disconnected G/R wire. Report the findings.

2) Plug the G/R wire back on to the ignition light. With the ignition ON, and the car not running, the light should be "ON" but you report that it is not. Try running a known good ground wire to the alternator and voltage regulator and touch different spots on both those components just to see if you can get the ignition light to illuminate. For instance, touching a known good ground wire to the VR case and making the light come on each time you did that would be a really nice sign. Report back.

3) Insert a fuse in to Fuse #3 and turn the key ON, but do not start the car. See if your gauges, heater, and wipers work or if you blow the fuse doing that. Report back.

We are making progress.

First test did not show any voltage or illumination. I ran a ground wire from the engine block to the center pin of the ignition bulb with the ignition "ON" and no illumination. Checked with a DVM and sure enough no voltage across the connections.

Running second test now...

[patrickt]

Can you get that ignition light to illuminate by just running 12v+ to one pin and 12v- to the other pin? All we're doing here is just testing the light bulb to see if it will come on.

[ACHiPo]

I used the DVM rather than trying to see the ignition light since I'm working alone.

Ignition light side terminal grounded to block, G/R wire connected to ignition light center terminal. DVM clipped to ignition light center terminal.

With ignition "on" (no 3 fuse):
Light to VR ground 0V
Light to alternator case 0V
Light to alternator Batt terminal 13.7V
Light to all other alt terminals 0V

Turned key off, inserted fuse, turned key on. Alt spiked to -15A and fuse blew. Light did not illuminate.

[ACHiPo]

The resistance across the ignition light terminals is 7.5 Ohms. It lights when battery power is applied.

Need to head to work, but will check back later today.

[patrickt]

OK, fuse out, run a 12v+ line to the pin on the light that originally had the two green wires that you removed, and the G/R wire is now attached back to its pin. When you do that does the light illuminate? If not, and you're absolutely 100% positive that the light works and that you are giving it 12v+ on one side, then that means it is not getting a return path on the other side through the VR. Double check this test as it is important.

[patrickt]

All we're doing on this test is just making sure the ignition light is not broken somehow and that the G/R wire coming from the voltage regulator does indeed provide a path to ground when the car's alternator is not charging. When behaving normally that G/R wire will provide a path to ground until the car begins charging, and then the path is gone. That's what makes the ignition light come on and off.

[HighPlainsDrifter]

Hi,
Hard to find shorts.
While you are in there it might be a good idea to get rid of the ammeter and run a voltmeter. All the power for everything goes through the ammeter and when not functioning can heat up quickly and start a fire. I don't think it's worth the risk. Just my perspective, 33 years in electronic industry.
Perry

[ACHiPo]

Originally Posted by patrickt

All we're doing on this test is just making sure the ignition light is not broken somehow and that the G/R wire coming from the voltage regulator does indeed provide a path to ground when the car's alternator is not charging. When behaving normally that G/R wire will provide a path to ground until the car begins charging, and then the path is gone. That's what makes the ignition light come on and off.

Patrick,
Thanks. I will run this test when I get home tonight and post the results.
Evan

PS I have a short tester ordered. It should be here Friday, so hopefully can isolate the wire by then.

[ACHiPo]

Originally Posted by patrickt

OK, fuse out, run a 12v+ line to the pin on the light that originally had the two green wires that you removed, and the G/R wire is now attached back to its pin. When you do that does the light illuminate? If not, and you're absolutely 100% positive that the light works and that you are giving it 12v+ on one side, then that means it is not getting a return path on the other side through the VR. Double check this test as it is important.

+12V to the two green wire pin with the G/R connected--bulb lights up. Makes sense given that the bulb lit up when I cranked in the previous test. Not sure why the bulb isn't lit when key is in the "ON" position?

I'm back to suspecting the voltage regulator, although maybe I should disconnect the fan and wipers to eliminate them as the source of the short (assuming I can get to the connections)?

Originally Posted by patrickt

When behaving normally that G/R wire will provide a path to ground until the car begins charging, and then the path is gone. That's what makes the ignition light come on and off.

The fact that the bulb is not lit when the key is "ON" suggests that when the key is in the "ON" position, there is no power to the ignition light. Could I have a short in the ignition switch? Seems unlikely when the car starts and runs ok?

[ACHiPo]

Some additional data. Not sure what to make of it other than there is definitely a connection to ground on the fuse 3 circuit, and it's not between the ignition switch and the fuse (that tests as open). All tests were made with the battery cut off in the "off" position. The ignition light is out of the circuit.

Testing the right side of the fuse terminals to ground:
1 Open
2 Open
3 0.7 Ohm
4 Open
5 Open
6 1 Ohm
7 0.7 Ohm
8 0.8 Ohm

[hauss]

Try a different battery, I had a internal short once and it gave me hell. Sounds like it may be your problem. Also it is easy to do .

[patrickt]

Originally Posted by ACHiPo

I'm back to suspecting the voltage regulator, although maybe I should disconnect the fan and wipers to eliminate them as the source of the short (assuming I can get to the connections)?

We are going to treat the problem as, potentially, having more than one source. That means getting the charging circuit to work normally, then we'll move on to the short on the GREEN line that runs from the fuel gauge, to the tach, to the wipers, etc. Here is the next test:

Remove Fuse #3 and keep it out throughout the testing. Likewise, remove the double GREEN wire from the pin on the ignition light and keep it off throughout the testing.

Run a fused wire from the ACC terminal of your ignition switch (WHITE wire) to the exposed pin on the ignition light that had the two green wires on it. The G/R wire should still be attached to the ignition light normally.

Then remove the four wire plug from the voltage regulator and jumper a new ground wire from ground to the G/R wire hole in the plug. Do not re-insert the plug, just leave the temporary ground jumper in it.

Turn the key "ON" and see if the ignition light comes on.

If the light comes on, check to see if you have 12v+ at the Y/R wire hole on the plug.

Report back.