Made a mistake rewiring the car!

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Model T Ford Forum: Forum 2012: Made a mistake rewiring the car!
Top of pagePrevious messageNext messageBottom of page Link to this message  By Bernard from San Buenaventura, Calif on Thursday, April 19, 2012 - 10:02 pm:

Phase 2 of the "un-restoration" of my Speedster seemed to be finished. It involved rewiring the car completely. I mean every single wire, a new firewall block, and a new gauge cluster/ignition switch (factory paint!) off T-Bay.

I ordered the large wiring diagram and found it very easy to follow, almost idiot proof. Well, not quite. When I put the battery on the trickle charger today to slowly check everything, starting with the low beam headlights, I got nothing. Shortly after I noticed some sparks coming from the gauge cluster and immediately killed the battery power. I removed the cluster, inspected it, yet couldn't find any "welding signs" anywhere. While I let the gauge cluster hanging upside down it touched the coilbox and . . . . crrrrr . . . there it was again. Killed the battery and had another close look.

Turns out that I managed to hook up the yellow BATT wire not to the BATT terminal on the ammeter, but to the little screw next to it, effectively giving battery power to the entire gauge cluster. Not good.

I have now fixed that fauxpas, but before I hook the battery up again, I want to get some feedback, if you don't mind.



1) Since battery power was applied to the coil box, albeit for only a fraction of a second, do I realistically have to fear that I fried something inside, like my freshly rebuilt coils? (Ron, would that effect my warranty? :-))

2) I now have both main terminals of the ammeter HOT. Of course, one gets battery power directly from the terminal block and thus from the battery, the other one is connected to the switch where it also gets power. Is that okay?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Thursday, April 19, 2012 - 10:16 pm:

The ammeter wiring doesn't look right. The only wires should be on the two large center terminals. No wire to those little screws in the case back.



Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike D, Williamsburg VA on Thursday, April 19, 2012 - 10:29 pm:

This might help


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Thursday, April 19, 2012 - 10:31 pm:

As crazy as this sounds, if that entire cluster was mounted to those metal brackets and they in turn were mounted to a wood firewall only and not to anything else then you would have simply connected the battery to the outer metal of the cluster and that circuit would have completed to the yel/black wire coming from terminal #1 of the terminal block and other than not having a hot wire to anything but the generator - you likely would not have hurt anything. I suspect however that the brackets mounting your cluster are in fact mechanically connected to something other than a wood firewall. Post some pictures of the whole thing firewall and all and see whether the outer metal parts of the cluster are connected to anything since that is what you had your battery connected to. As others have pointed out you have more than one mistake. The yellow/black wire coming from the harness and in the picture connected to ground on the ammeter back, should in fact be connected to the BAT terminal on the ignition switch and not to any part of the ammeter. The solid yellow wire hanging free should be connected to the BATT terminal on the ammeter as you have labeled it. The wire going from the BAT term on the ignition switch to one side of the ammeter is in fact correct.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jason Given - St. Paul, MN on Thursday, April 19, 2012 - 10:49 pm:

I cannot help you with your concerns about frying anything. But I used the Texas T Parts (http://www.texastparts.com/mm5/manuals/19-25WiringDiagram.pdf) wiring diagram when I wire mine. I labeled each end of each wire to match the numbering wiring schematic. This way I could visually ensure that the everything was connected to the correct terminal.

Wiring Diagram

Best of luck


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bernard from San Buenaventura, Calif on Friday, April 20, 2012 - 01:13 am:

Thank you all. I'm flabergasted. It appears then that the wiring diagram I have, poster sized, is wrong. Will scan it in the morning.

That is just crazy!


Top of pagePrevious messageNext messageBottom of page Link to this message  By mike_black on Friday, April 20, 2012 - 11:48 am:

That happens, Bernard! While doing my first TT in 1977, I ripped out all the wires without marking anything because I had a wiring diagram! I rewired it exactly as the diagram said and it didn't work. I had 2 more books--each with different diagrams--they didn't work either. An 80 year old friend looked at all my diagrams and laughed. He then moved some wires around and everything worked!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Smith on Friday, April 20, 2012 - 12:54 pm:

What are those extra screws on your ampgauge?Never have seen them.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez on Friday, April 20, 2012 - 01:27 pm:

Bernard,

You effectively grounded the hot wire from the battery to the chassis. The little screws hold the ammeter movement inside the case, and the case is grounded to the car (somehow). So as John R stated probably no damage done. The worst case would be a burned wire ...since you saw sparking, the connection to ground was poor so damage was likely averted.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bernard from San Buenaventura, Calif on Friday, April 20, 2012 - 04:11 pm:

First,
I should not forget to thank all of you for being so helpful here. It truly makes the Model T experience a rewarding one!

Now to the wiring. It looks like there's at least 2 ways to skin this cat.

1) The wiring diagrams of John Treace, Mike D, as well as the explanation of John F Regan suggest to attach the yellow-with-black-tracer generator wire to the BATT terminal of the switch.

2) The wiring diagram of Jason Given from Texas T Parts is identical to the one I purchased. It suggests to attach the yellow-with-black-tracer generator wire to the right-hand-side main terminal of the ammeter.

Thinking about it, both ways should be fine, as the crossover wire that attaches the switch unit to the ammeter is connecting both possible attachment points anyway.

So let's have a look at the fabulous wiring diagram I purchased.



Yep, it's big. Made for idiots like me.

Now let's have a closer look at the gauge panel wiring:



You may see why I attached the generator wire at the smaller terminal, not thinking this through, really.

Anyway, I have now attached the generator wire to the main terminal of the ammeter, one of the reasons being that it's a bit short to reach over to the BATT terminal, and, as I indicated before, it should be the same difference anyway.



So unless somebody now tells me why attaching that generator wire to the ammeter, as shown in the Texas T and in my wiring diagram is different from attaching it to the switch unit, I will proceed to the next step, most likely tomorrow morning, and see if I can get the car started and running on both, BATT and MAG again. Not only do I have a new wiring loom, new connector block, new headlights, but I also have a new coil box and a set of newly rebuilt coils, meaning, I could have messed up at quite a few steps along the way. One thing I already noticed is that the headlights seem to have the same brightness in the DIM and BRIGHT position. Hmm . . .


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Friday, April 20, 2012 - 04:21 pm:

Bernard
I help people with Model T electrical problems all the time and got tired of the incorrect wiring diagram floating around
Here is the only fully correct wiring diagram I know of available that DOES NOT at least one wiring error depicted.
1
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez on Friday, April 20, 2012 - 08:50 pm:

Bernard,

Ron's diagram is spot on.
The ammeter measures current flow only. If the load on the Battery exceeds the "electrical replenishment" from the generator then the needle will show Negative or minus.

If the Generator is "replenishing the electrical load beyond the demand" then the needle will show Positive or plus.

Since all electrical loads are connected to the battery only, then the ammeter is the indicator of "battery replenishment" or "battery loss" in the system.

Consider the battery your bank account, and the generator your income. It should become clear. Hope this helps!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bernard from San Buenaventura, Calif on Friday, April 20, 2012 - 09:35 pm:

I hate to identify myself as an idiot, but I rather do that instead of dying stupid.

The GEN terminal of the ammeter is connected to the BATT terminal of the switch unit via the yellow-with-black-tracer generator wire. That means, or should mean, that there is power on both terminals regardless of whether the yellow-with-black-tracer wire coming from the generator is attached to one or the other terminals.

So if the battery is my checking account and the generator my income (I do get that), then my checking account is linked to my savings account, which would be the ammeter. Both terminals in question are connected, are HOT all the time, so whatever happens on the BATT terminal of the switch unit, should instantly (deduct speed of neutrons) on the GEN terminal of the ammeter.

What is is I'm missing?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Friday, April 20, 2012 - 09:43 pm:

After purchasing and using one of the big diagrams from one of the parts outlets (It was printed on blue paper), I wrote Ron asking why my car was not working right and he sent me his diagram, which I used to correct my wiring and my car worked perfectly after that. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez on Saturday, April 21, 2012 - 01:29 am:

Bernard,

True, except when the generator is making deposits, its moving cash (electrons) into your account. All other components of the system are making withdrawals... Lights, horn, coils, and the IRS of your system the starter!

If you're like me, my generator is having a hard time keeping up and a bigger battery won't help! I've had to quit blowing my horn and soon I'll have to shut off the lights... metaphorically speaking!

John


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bede Cordes, New Zealand on Saturday, April 21, 2012 - 03:47 am:

Bernard,

For testing purposes, you could consider the temporary fitting of a 10A or so fuse between the + terminal of your battery and the + cable heading away to your car's electrics just to make yourself less nervous when you try your altered wiring. The fuse should simply blow letting you know there is still a problem if there is still one, rather than high current flowing generating smoke in places other than the exhaust pipe. DO NOT try to start the car with the starter motor though, it's current draw will obviously blow the fuse. Once everything is proved fine, then take the fuse back out of the circuit. I think 10A should be ok, but perhaps Ron or someone could suggest a more appropriate value if required, maybe 15A could be needed ?

Hope this helps
Bede


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez on Saturday, April 21, 2012 - 10:42 am:

Bede, I think you missed something. The starter circuit is separate from the rest of the electrical system, so would not draw current through the fuse you suggest.

Regards, John


Top of pagePrevious messageNext messageBottom of page Link to this message  By J Berch on Saturday, April 21, 2012 - 02:37 pm:

Bernard, I would rotate those eyelet connectors just a little. They are very close to contacting the metal tabs that hold the switch together. The round top screw is against the heat shrink on the right. In time with vibration, deterioration and moisture these things could cause problems.

I bought a Fun projects in line fuse kit. It's cheap insurance and might save a lot of grief.



Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Saturday, April 21, 2012 - 04:14 pm:

Ford original diagrams and Ford actual on-the-car wiring has the yellow/blk wire coming from the cutout via terminal #1 on the barrier strip to the BAT terminal on the ignition switch rather than to the ammeter as shown on the TTP diagram and the fold out diagram that is partially pictured. I don't know who made that partially pictured diagram. The diagram that Ron Patterson posted is correct. The TTP diagram is wrong. Now you might think it makes no difference but in truth it does. It has to do with voltage drops which in a 6V system are important to pay attention to. Also I should point out that if your wiring is totally correct size and gauge then oddly it doesn't matter as much if you have the yellow/black wire in the wrong place at the ammeter. The issue is that the main power draw of the whole system is the headlights. You want the high current draw of the headlights to be wired directly to the power via the shortest path which is from the cutout to the ignition switch BAT terminal which is the source of current for the headlights. By connecting the cutout to the ammeter you then have to add voltage drops for the short link wire and the additional connection point at the ammeter. That matters only a little bit EXCEPT almost all repro link wires are made from lighter gauge wire than the correct #12 wire. Notice in the last picture that the yellow/black link wire is smaller Outside Diameter than the SOLID YELLOW colored wire located just above and coming from the battery to the other side of the ammeter. That solid yellow wire is #12 and correct. Soooooooo you need to just toss away incorrect wiring diagrams and use correct ones. The MTFCA pictorial diagram is correct as is the one Ron P. posted. I also agree with the physical positioning of the wiring terminals is marginal in the picture and you should address that. It is unfortunate that so many repro harnesses were made with #14 gauge used in all of the yellow/black harness wires. All 5 wires (3 yel/blk and 2 solid yellow) in the high current path were #12 gauge when the factory wired the car. With the yel/blak wires being lighter than correct gauge and also connect to the wrong place, your generator will have to put out a higher voltage to overcome these additional wiring losses and this also prevents the generator from properly charging the battery when the headlights are on since part of the voltage is lost. If you are using a VR the source voltage is regulated and fixed so you will have less voltage at your headlights and the battery will then be carrying part of the headlight load. It has to do with the current paths. Every wire is in fact a finite amount of resistance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bede Cordes, New Zealand on Saturday, April 21, 2012 - 06:12 pm:

Sorry John,

perhaps I should have clearly explained to put the fuse between the + battery terminal and + battery clamp, to make my explaination correct.

Bede


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Saturday, April 21, 2012 - 08:09 pm:

My posting had nothing to do with your posting Bede. I have no problem with your suggestion to insert a temporary fuse if the car has no fuse at all. That is in fact a very good idea. The correct fuse for a Model T is a 25 amp fast blow type fuse. It should be permanently installed in the heavy solid yellow colored main supply line that comes off the starter foot switch. It should be located as near as practical to the foot switch for maximum protection. It is the best insurance you can have to prevent a fire starting from the wiring harness. Shorts in the wiring not caused by a mechanic at work are then most likely to happen when the car is vibrating which probably means the car is moving.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bernard, San Buenaventura, Calif on Saturday, April 21, 2012 - 11:04 pm:

Once again,
I'd like to thank you all for your input. Since I had to shorten the wiring harness for the Speedster dash, and all of a sudden remembered that, I found the cutoff piece of the yellow-with-black-tracer wire and was thus able to replace the too short one. I followed the "correct" wiring diagram and attached it to the BATT terminal on the switch.



At the same time I move the STOP-lamp wire from the # 3 (BATT) position on the block to the # 1 (GEN) position, something I also learned from Ron's wiring diagram.



I hand-cranked the engine to life, allowed it to warm up a bit, checked timing and throttle rods, adjusted mixture and idle, leaned it out, and allowed it to run, which it did. Switch from BATT to MAG did -- for the first time -- not cause a drop in RPM, so Ron's freshly rebuilt coils did the trick indeed, and my mag is working as it should! After about 15-or-so minutes I turned off the car and the only thing that caught my eye as being not okay . . . . can you guess? . . . was the dripping water pump. I eventually want to get rid of it, but I need to find out if my radiator is up to the task, and the only way to do that is by driving it on an extended trip.

This concludes phase 2 of my un-restoration. Phase 3, the last one I can complete before the Santa Clara Speedster run, is to strip all 5 wire wheels, repaint them, install new rubber inside and out, and make a pattern for the leather covers for the bucket seats.

In June then, phase 4 involves fitting fenders and running boards.

Again, it's been so much fun with you guys, that even a mechanically challenged guy like me can do this on his own!

Thank you all!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bede Cordes, New Zealand on Monday, April 23, 2012 - 04:17 am:

John Regan, no problem, I wasn't correcting you, it was for John Semprez's post a couple above yours.

Working with 3 ph 400v mains electrical equipment that can draw in excess of 1000's of amps continuously for a job makes you appreciate fusegear and protection !

Regards,
Bede


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez on Monday, April 23, 2012 - 12:20 pm:

Sorry Bede,

I wasn't thinking of a sacrificial fuse for testing! Your idea is a good one, however as John Regan pointed out a fuse in the yellow lead is a good if not necessary permanent solution. I thought that was what you were describing. My error.

When I was doing factory automation on old wiring, I was taught never to trust old wiring tags... and to ring out each wire from source to load. When unsure we would use sacrificial fuses to test circuits as you suggested. -John S.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bernard, San Buenaventura, Calif on Monday, April 23, 2012 - 12:21 pm:

One more remark regarding the incorrect wiring diagram and the incorrect wire gauge for the yellow battery wire . . . the wiring loom, purchased for ridiculous little money from Lang's, is also too short to be routed nicely from the generator to the coils and wiring block. The black cloth sleeve is coming apart the moment it's taken out of the plastic. I'm glad that the parts are so inexpensive, but I wouldn't mind spending $10 (1/3) more for a wiring loom that addresses these shortcomings, $15.00 (50%) more if it was made in USA.


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