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

ACHiPo · #1 (**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 · #2 (**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.

Blas · #3 (**permalink**) 05-25-2019, 09:29 PM

As I recall, there was a similar issue years ago on some CSX cars. I believe it was determined the problem was in the ignition light housing. Blas

ACHiPo · #4 (**permalink**) 05-25-2019, 10:58 PM

Quote:

Originally Posted by Blas

As I recall, there was a similar issue years ago on some CSX cars. I believe it was determined the problem was in the ignition light housing. Blas

Thanks. I’m pretty sure I already eliminated that as a possible cause, but I don’t really trust any troubleshooting I did with the voltage stabilizer installed.

ACHiPo · #5 (**permalink**) 05-25-2019, 10:56 PM

Quote:

Originally Posted by patrickt

Alright, I'm now betting on the tach.

I’ll try it tomorrow, but I’m skeptical. I had the tach out of the circuit when I was blowing fuses last weekend.

I’m betting on the fuel sender, the troubleshooting of which was masked by the voltage stabilizer in the circuit.

Hopefully one of us is right!

ACHiPo · #6 (**permalink**) 05-26-2019, 12:01 PM

I took a break yesterday to fabricate a brass tool to loosen and tighten the dash switch nuts. Works pretty well!

Unplugged the tach, still short to ground at heater switch light green wire. Checked light green wire at tach connector--shorted to ground. There are two black wires loose behind the tach. I'm pretty sure they were that way before I started messing around behind the dash, and given that the light green wire is still shorted to ground I doubt they have anything to do with anything.

Unplugged the fuel gauge double green wire. Double green wire shorted to ground. Light green heater switch wire still shorted to ground.

Removed ignition light fixture. Double green wires shorted to ground (wire lug removed from fixture). Center pin green wire open to ground.

patrickt · #7 (**permalink**) 05-26-2019, 12:27 PM

Alright, what do we have left on there... wiper switch?

ACHiPo · #8 (**permalink**) 05-26-2019, 01:07 PM

Quote:

Originally Posted by patrickt

Alright, what do we have left on there... wiper switch?

Yes, wiper switch and fuel sender seem to be the only things left.

ACHiPo · #9 (**permalink**) 05-26-2019, 12:36 PM

Looking at the picture above, I realized the pink wire that goes to the fuel sender is crimped with the light green wire. As tempted as I am to clip that pink wire to isolate it, I'd rather find a non-destructive way to confirm that the fuel sender is the source of the short.

There is a connection by the driver's side rear wheel next to the fuel line. I'm pretty sure that is the connector for the fuel sender. It's difficult to get to with the car on the ground, but I may be able to disconnect it. Before I do, I want to figure out what the yellow and two black wires are. If they are just redundant for the different fuel sender types I can disconnect them no problem. I'm concerned, however, that the wires may go somewhere else (like the tail lights).

patrickt · #10 (**permalink**) 05-26-2019, 12:46 PM

OK... if it was me, I'd just cut the pink wire and, if it turned out not to be the culprit, butt-crimp it back together.

ACHiPo · #11 (**permalink**) 05-26-2019, 01:10 PM

Quote:

Originally Posted by patrickt

OK... if it was me, I'd just cut the pink wire and, if it turned out not to be the culprit, butt-crimp it back together.

May do that. Just thinking through to make sure removing power from the fuel gauge circuit won't mess anything else up.

ACHiPo · #12 (**permalink**) 05-26-2019, 05:19 PM

Alright, definitely found an issue with the fuel sender. I cut the wire at the tach, tested continuity and it was open from ground to the pink wire connected to the tach, and shorted to ground on the fuel sender side.

Put a fuse back in #3, turned the ignition to "ON". No ignition light (just dawned on me that I don't have a light because the "I" terminal of the voltage regulator is still disconnected. Will remedy that an report back). Checked the fuse, it's still intact. Started the engine. Charges normally. Turning on the fan causes the ammeter to drop as it should.

That's the good news. Now for the rest of the mystery.

After installing a spade terminal connector splice in the pink wire, I checked continuity to ground again. It's now open.

I turned the key "ON" and connected the pink wire going to the fuel sender to ground and the fuel gauge started rising slowly (the voltage stabilizer is back in the circuit). I started the engine and everything seems normal. The fuel gauge stabilizes about 5/8 which is about right.

Where did my short go?

patrickt · #13 (**permalink**) 05-26-2019, 05:54 PM

Quote:

Originally Posted by ACHiPo

Where did my short go?

Jeez. Try wiggling wires to see if you can get the fuse to blow. If you can't, then leave the ignition light disabled and the charging configuration set up so that it works without the light. If you can make it through the summer without blowing the fuse again then you can hook it back up over the winter.

ACHiPo · #14 (**permalink**) 05-26-2019, 07:29 PM

I'm pretty confident I've eliminated the short, although I suspect I still have a problem with the fuel sender. It almost acts like the fuel sender was acting as a short, but when I cut the wire it somehow reset itself?

Everything is now hooked up as it was delivered with the exception of the pink wire going to the fuel sender, which is floating (disconnected).

The ignition light works properly and the charging system is working correctly. I've run the engine for several minutes, and even took the car for a drive around the block and everything seems to be working correctly (except the fuel gauge).

The fuel gauge worked when I jumpered between the pink wire and the (floating) case of the voltage stabilizer. It also worked when I disconnected the jumper and grounded the case of the voltage stabilizer. I noticed on the test drive (about 5 minutes after the gauge seemed to work) that the needle had dropped back to E.

It seems like the sender pink wire wants to be grounded? I wish I knew why it's changed.

I don't have a problem with that if it works and doesn't cause another problem, but I think I'll hold off making that mod until I talk to Bob Tuesday.

patrickt · #15 (**permalink**) 05-26-2019, 07:42 PM

Quote:

Originally Posted by ACHiPo

It seems like the sender pink wire wants to be grounded? I wish I knew why it's changed.

I don't have a problem with that if it works and doesn't cause another problem, but I think I'll hold off making that mod until I talk to Bob Tuesday.

On the schematic, the pink wire is hot for a tube-type sender. From the schematic, if you grounded the pink wire it should blow the fuse....

ACHiPo · #16 (**permalink**) 05-26-2019, 08:28 PM

Quote:

Originally Posted by patrickt

On the schematic, the pink wire is hot for a tube-type sender. From the schematic, if you grounded the pink wire it should blow the fuse....

Yep. And yet...

The mystery continues...

patrickt · #17 (**permalink**) 05-27-2019, 05:53 AM

Well, it could be the sending unit. With the pink wire disconnected, everything except the fuel level meter works perfectly. So, I would try running a fresh, temporary, fused wire to the pink wire connection at the fuel sender unit. Disconnect the existing pink wire at both the dash end and the fuel tank end (just in there's a chaffing fault along it somewhere). Put a five amp fuse on the new fresh wire and run it to the pink terminal at the sender unit and then see if: 1) the fuel level gauge works when the car is on, and for how long, or 2) whether that new fuse blows. If the new fuse works for a while, and then blows, upping the amp value of the fuse might be a possibility to consider... but it is the fuel tank....

ACHiPo · #18 (**permalink**) 05-27-2019, 08:06 AM

Quote:

Originally Posted by patrickt

Well, it could be the sending unit. With the pink wire disconnected, everything except the fuel level meter works perfectly. So, I would try running a fresh, temporary, fused wire to the pink wire connection at the fuel sender unit. Disconnect the existing pink wire at both the dash end and the fuel tank end (just in there's a chaffing fault along it somewhere). Put a five amp fuse on the new fresh wire and run it to the pink terminal at the sender unit and then see if: 1) the fuel level gauge works when the car is on, and for how long, or 2) whether that new fuse blows. If the new fuse works for a while, and then blows, upping the amp value of the fuse might be a possibility to consider... but it is the fuel tank....

Sometime overnight I remembered Doug telling me to remove the connector behind the driver's side rear wheel and short the forward pink wire to ground. If the gauge responded it meant the fuel sender was bad. (This was several weeks ago when I just had a flaky gas gauge).

My guess is that the gauge was not reading correctly yesterday, but was just responding to having the pink wire grounded. If that's the case, then the gauge would have continued to climb to full given enough time.

So I definitely have a bad sending unit.

I still don't understand what happened to the short? I like your idea of running a separate fused wire to to the pink sender, although I think I will try inserting the fuse where I've already cut the wire. I can run a 5A fuse in that wire and a 15A in #3 so the fuel sender fuse would blow first and not impact my charging.

I'm also going to call Bob and Peter first thing tomorrow and get their ideas.

I think I need to drop the tank to replace the sender? At a minimum I will need to get the car up on a lift to access the sender wire at the sender if it seems there is a chafed wire.

ACHiPo · #19 (**permalink**) 05-28-2019, 01:42 PM

An update from yesterday. The problem is not fixed. When I turned the ignition "ON" yesterday, no ignition light. Checked fuse 3 and sure enough it was blown. Replaced the fuse with a 15A one and it blew as well. Changed the wiring back to Bob's recommended configuration eliminating the stator connection on the alternator, removing the "I" spade from the VR, and jumpering the A and S spades on the VR. The pink wire is still disconnected from the fuel sender. The charging works again, but of course no tach or anything else on the ignition circuit.

patrickt · #20 (**permalink**) 05-28-2019, 02:04 PM

Quote:

Originally Posted by ACHiPo

An update from yesterday. The problem is not fixed. When I turned the ignition "ON" yesterday, no ignition light. Checked fuse 3 and sure enough it was blown. Replaced the fuse with a 15A one and it blew as well. Changed the wiring back to Bob's recommended configuration eliminating the stator connection on the alternator, removing the "I" spade from the VR, and jumpering the A and S spades on the VR. The pink wire is still disconnected from the fuel sender. The charging works again, but of course no tach or anything else on the ignition circuit.

And with all that disconnected, if you put a fuse in #3 it still blows?