Charging System Troubleshooting--Blown Ignition Light Fuse? - Page 4

ACHiPo · #61 (**permalink**) 05-18-2019, 08:50 PM

Thanks. Done for the night, but will hit hit hard again tomorrow.

DanEC · #62 (**permalink**) 05-19-2019, 06:03 AM

Man - this is more challenging than any of my electrical sorting out issues. Hope you all figure it out soon.

patrickt · #63 (**permalink**) 05-19-2019, 08:05 AM

I can not think of a reason why turning the ignition switch on would turn the fans on. The fan relay on the firewall has a positive feed that is always hot. The negative feed to the relay goes through 1) a thermostatic switch in the radiator hose; and 2) a manual switch on the dash. The negative feed for the fans themselves comes off the X-member at the front of the car.

Put everything back as per the previous post, then gently wiggle things under the dash -- see what happens. Then turn the key on, gently wiggle things under the dash -- see what happens.

Just to check -- this car was wired by the boys at ERA and has not been touched by anyone else, correct?

ACHiPo · #64 (**permalink**) 05-19-2019, 08:24 AM

Quote:

Originally Posted by patrickt

I can not think of a reason why turning the ignition switch on would turn the fans on. The fan relay on the firewall has a positive feed that is always hot. The negative feed to the relay goes through 1) a thermostatic switch in the radiator hose; and 2) a manual switch on the dash. The negative feed for the fans themselves comes off the X-member at the front of the car.

Put everything back as per the previous post, then gently wiggle things under the dash -- see what happens. Then turn the key on, gently wiggle things under the dash -- see what happens.

Just to check -- this car was wired by the boys at ERA and has not been touched by anyone else, correct?

I’m the only person other than Doug, Bob, and Dan that has touched the wiring.

The fan coming on doesn’t make sense to me, either. I have a couple thoughts: 1) I wiggled something that shorted the temperature sensor to the ignition circuit so when the key is on it tells the fan to turn on, or 2) it has something to do with my initial observation that when I unplugged the fan and the car hit temperature, the ammeter went positive. (Something that makes no sense to Bob or me, thus I doubt my observation of it and want to duplicate it). I tried duplicating this, but discovered the manual fan switch was broken (the switch is removed from the dash and hanging by its wires). As I type this I’m thinking I need to remove the switch completely and tape the lugs—as I recall the manual switch does not turn on the fan with the key off. There might be something conductive in the open manual switch that is turning on the fan.

On another note, I now have several cases that suggest I need to have fuse 3 intact to charge, even with Bob’s configuration. Why would that be? If that is the case, I need to fix the cause of fuse 3 shorting to solve my charging issue. Think I will give my short detector a shot.

ACHiPo · #65 (**permalink**) 05-19-2019, 08:28 AM

Quote:

Originally Posted by DanEC

Man - this is more challenging than any of my electrical sorting out issues. Hope you all figure it out soon.

It is definitely character building! When I find the problem, I guarantee it will be quite obvious and simple in hindsight.

ACHiPo · #66 (**permalink**) 05-19-2019, 10:03 AM

Dummy head-face alert!!!

The fan issue is resolved. While the fan did come on when the ignition was turned on, it was the foot box fans--the switches had gotten flipped after I had dropped the panel off the bottom of the dash.

D'Oh!

Now back to your regularly scheduled programming of head scratching...

patrickt · #67 (**permalink**) 05-19-2019, 10:09 AM

Well, that's a relief.

ACHiPo · #68 (**permalink**) 05-19-2019, 10:26 AM

A new clue.

With Smiths stabilizer installed and grounded to the fuel gauge, fuse 3 removed and VR modified per Bob's instructions I turned the ignition "ON". No light, no sounds--just what was expected.

I then started the engine, the ammeter moved positive for a few seconds, then back to 0.

I turned off the engine, checked fuse 4 and sure enough it's blown.

patrickt · #69 (**permalink**) 05-19-2019, 10:36 AM

Double check that you made the wiring mods exactly as Bob outlined. If that is different than this then let us know: 1) Disconnect the RED and GREEN wires going to the voltage regulator; 2) Run a 12v+ wire to the S pin of the voltage regulator (the one that used to have the RED wire going to it and that you have now removed).

Repeat the test making absolutely sure the voltage regulator is grounded, use an extra ground wire with alligator clips to clip on to the VR itself, and see if you get the same results. If you do, replace the Voltage Regulator.

ACHiPo · #70 (**permalink**) 05-19-2019, 10:49 AM

Patrick,
Bob suggested I wire the VR like it was before the ignition switch was added by jumpering A and S. The A (Y/R wire) and S (W/B wire) terminals are jumpered into the VR. The I (G/R) is removed and isolated (taped).

Looking at the schematic again, I see that I need to disconnect the "S" wire between the alternator and VR. That's hopefully what's blowing fuse 4.

ACHiPo · #71 (**permalink**) 05-19-2019, 11:19 AM

Yep, that was it. I disconnected the stator wire from the alternator and taped it and the system is charging as expected.

Yeeehaw!

Question: Does this totally eliminate the VR and alternator as root causes, or could I still have an issue with my VR?

patrickt · #72 (**permalink**) 05-19-2019, 11:22 AM

We will check the VR's ignition light circuitry after we eliminate the fault on the green line.

ACHiPo · #73 (**permalink**) 05-19-2019, 12:56 PM

Just started the engine again and let it run for a few minutes. Charging continues to work correctly. Unfortunately it's raining today, otherwise I'd drive it long enough to get it up to temp and make sure no weirdness with the fan circuit.

At this point I'm just happy to be able to drive to my BAR Referee appointment tomorrow with a high probability of the charging system working!

patrickt · #74 (**permalink**) 05-19-2019, 01:20 PM

Quote:

Originally Posted by ACHiPo

Just started the engine again and let it run for a few minutes. Charging continues to work correctly. Unfortunately it's raining today, otherwise I'd drive it long enough to get it up to temp and make sure no weirdness with the fan circuit.

At this point I'm just happy to be able to drive to my BAR Referee appointment tomorrow with a high probability of the charging system working!

Now, you can cut the odds of finding the fault in half by separating the two wires on the driver's side of fuse #3. One is W/G the other is LtG. Remove those two wires, put a fuse in the fuse holder, and with the key ON, touch each wire, one at a time, holding it there for 30 seconds, and see which one blows it. If you're really lucky, it'll be the LtG wire.

ACHiPo · #75 (**permalink**) 05-19-2019, 02:03 PM

Need to buy more fuses

Will try your test after running errands (including getting more 10A and 15A fuses) this evening.

ACHiPo · #76 (**permalink**) 05-19-2019, 02:31 PM

I found a fuse, but the two wires are crimped in a single ring lug. I really don’t want to try removing the lug as there’s no slack wire from the harness.

I’ll try my short detector and see what it shows.

ACHiPo · #77 (**permalink**) 05-19-2019, 02:50 PM

Turns out the “short detector” is nothing more than a continuity tester. Guess what? There’s a short to ground at fuse 3. Who’d a thunk it?!

Grrrrr

https://www.amazon.com/Automotive-Tr...25471281&psc=1

patrickt · #78 (**permalink**) 05-19-2019, 02:56 PM

Quote:

Originally Posted by ACHiPo

Turns out the “short detector” is nothing more than a continuity tester. Guess what? There’s a short to ground at fuse 3. Who’d a thunk it?!

Grrrrr

]

If you have a compass and an automotive turn signal flasher unit you can make your own. That's all the fancy ones do (well, maybe a little bit more sophisticated). They just send a signal through the line and then use a little receiver to pick up the signal. When the signal is no longer present in the line, you've found your short.

ACHiPo · #79 (**permalink**) 05-25-2019, 07:02 PM

Got a little bit of data today. At this point I'm pretty sure the problem is not on the heater portion of the circuit.

I pulled the heater switch out of the dash and checked continuity. The light green wire is shorted to ground (not too surprising since it is connected to the W/G wire which is also shorted to ground when measured at the fuse block).

The orange wire connecting the heater switch to the heater fan is 49 Ohms, so seeing the motor windings before ground. This seems ok.

The heater switch is ok.

Because it was easy, I pulled the connector off the wiper motor just to make sure it wasn't shorted and it's not. The light green wire is still a short to ground.

It seems like the short has to be between the wiper switch and ignition light, ie I'm back to suspecting the short is at the tach or fuel gauge. Will drop the dash again tomorrow and pull the tach and fuel gauges (again). If nothing else it gives me a chance to reinstall the Smiths voltage stabilizer on the fuel gauge.

patrickt · #80 (**permalink**) 05-25-2019, 07:20 PM

Quote:

Originally Posted by ACHiPo

It seems like the short has to be between the wiper switch and ignition light, ie I'm back to suspecting the short is at the tach or fuel gauge. Will drop the dash again tomorrow and pull the tach and fuel gauges (again). If nothing else it gives me a chance to reinstall the Smiths voltage stabilizer on the fuel gauge.

Alright, I'm now betting on the tach.