Thanks for all the good info Julie, My gauges only have two posts on the back of them. The bar shunt hooks all them together with one of the posts and the other post have an individual wire going to the wiring harness from each gauge. So if I'm understanding you correctly I'll remove the bar shunt and hook a reducer to each gauge, in series. I suspect those other wires that run from each gauge to the harness are the wires that run to the sending units and I leave them alone. Am I anything close to being right?? Sorry if I'm so hard to get to understand how to do this. I'm a paint and body man not and electrician. Give me a hammer, a gallon of bondo and some paint and I'll make it pretty again, give me a handfull of wires and I'll burn something down. Glenn

 

"Damn it Jim, I'm a Doctor not a paleontologist"

sorry, sometimes it just comes out.

 

Lol, how about a psychiatrist. Is there a psychiatrist in the house!!!

 

NOTE TO ALL:

THE WIRING DIAGRAM LISTED IN POST 16 ABOVE IS INCORRECT (I TRIED TO DO IT TOO QUICKLY AND WILL ATTEMPT TO GET IT REMOVED). PLEASE USE THE ONE LISTED ON THIS POST BELOW!

Hi Glenn,

No problemo, and yes you are VERYclose to being right (gauge power will be in parallel not series). The gauge does have only two posts on the back of it. The resistor should have a hole on one end, a post of it's own on the other on the other, and a little pigtail wire with a connector on the end of it. Here's a picutre:



Here is a step by step procedure:

1. Disconnect the battery negative cable from the battery.

Note: On the back of each gauge itself there will be only two posts with nuts. One has a wire on it, the other has the power bridge (metal shunt). Each gauge is secured to the instrument panel by two screws.



This is a 51/52 gauge cluster. The square object
to the left are the circuit breakers used in the
original power distribution. Although shaped
differently, the gauges are the same, mounted
the same (mechanically) and wired the same
(electrically) on the 48-50 and 53-55 trucks.


2. Disconnect the individual wire on the back of each gauge that goes to the sending unit and LABEL IT.

3. Remove the nuts holding down the metal shunts and remove the shunts. Save the nuts - toss the shunts.

4. Install one voltage reducer (the "power in" side if it's labelled - might just be the open hole) on each gauge post where the shunt was connected.

5. Install the nut that used to hold down the shunt over the reducer to hold it on the stud - but leave it loose.

6. Loosen one screw that is securing the gauge in the cluster panel, slip the little pigtail wire connector attached to the reducer under it and tighten the screw. This provides a ground for the reducer.

7. Position the reducer so it is tucked in a good place over the top of the gauge and (carefully)tighten the nut holding it to the post that you installed it on earlier.

8. Connect a power supply wire to the open "Power in" stud on one reducer.

9. Connect a jumper wire from the stud on the first reducer (that has the power supply wire on it) to the same post on the second reducer, then on to the same post on the third reducer.

10. Reconnect the correct harness wire from the appropriate sending unit to the open stud on the gauge (the stud the reducer is not connected to).

11. Reconnect your battery ground cable.



Should work fine then.

 

Julie, thank you, thank you, thank you. I have finally seen the light. I got this project under control. You couldn't have explained it any better than that. Thanks for the diagrams and help. Now I know what I need to do. When I get this truck done I promise I'll post some pictures of it. It's turning out great. Thanks Glenn

 

Super!

Don't hesitate to ask about anything!

 

Julie you've been so nice and so helpful I hate to do this but I've got just one more tiny little itsy bitsy question. I went to hook up the wires to the ignition switch and noticed there are no markings on the back of the switch telling me which terminals are for what. The diagram that came with the wiring harness tells me what wires hook to which terminals but since the terminal aren't marked, I'm lost again. I tried to post a picture of the back of the switch but couldn't figure out how to do it. If you're looking at the switch from the back, after it is installed, it has one post that is longer than the rest which is positioned to the middle left side of the switch, then you have a shorter one to the upper right of that and another short one to the lower right. I would appreciate any help that I can get on this. Thanks in advance for any help. Glenn

 

Wow! most of us would never admit something like that.

AFA the search function: don't bother with the basic search box, click on the advanced search and search from there. Drill down in the "search in forums" box and highlight this forum so you don't get stuff that doesn't pertain to our trucks. You can also/or specify to search on a user name, so if you are looking for electrical info that didn't come up in your search on "electrical" you might do a search for posts by "Julies Cool F1". (be sure that you have put in the user's name EXACTLY as they have it, including spaces and capitalizations)
If you want to find info on 6V to 12V conversions only, use quotes around the phrase thusly: "6V to 12V conversions" as the keyword and you'll get results that have that whole phrase somewhere in it. If you leave off the quotes, you'll get results that has any PART of the phrase in it, so you'll get hits on 6V, 12V, and/or conversions (of all types, such as engine, AC, power steering, model, etc. conversions). You don't have to put something in every box on the advance search page, but the more parameters you put in the more specific the results will be.

 

Oh boy, it's always those itsy bitsy electrical questions that kill ya - sigh

Adding to what AX said, check out my galleries...all of my electrical drawings are there in gallery #4

Ok so let me review....we are working on a 1948? I think? And there's no labels on the back of the switch?????? Hmmmm???? Not even a "B" and "A" or and "I" That's really weird - there should be. Could you check again for me - look really close.

Ok another question for you (because this may not be a stock switch). How many posts are there on the back 3 or 4?

If there are 4 it is not a stock switch. But, I can tell you the one in the center is to turn the starter over.

Let me know and I'll try and sort it out for you.

PS Hey Blocker, send me the picture of the back of the switch directly to: babbiebuddie at ***.net (no gaps in the address and sub the "at" for @ - ya gotta manipulate th eaddresses in the posts or they get pulled)

 

Thanks again Julie,
When I took a couple more good pictures to send you i was able to zoom in and see some small writing that I couldn't make out before. I do see some letters next to the terminals. It looks like the letters, GA, AM, RAD. I'll still me email you the picture and let you tell me what goes to what. Thanks a bunch. Glenn

 

HI Glenn,

I got your picture and it is a stock 48 ignition switch.

OK I think I’ve figured out the hook-ups- the GA gave it away .

The GA/RAD post is for your accessories and would be the “ACC” post on any other switch. It goes over to power your temp, oil, and gas gauges, and if you installed a radio, power for it would come from this post as well. Take a look at the diagram that I attached.

One of the other two posts should have an “I” or a “C” for ignition or coil; and the last one should have a “P” or a “B” for power or battery. That last wire – power or battery comes off the “BATT” post of the 30 amp circuit breaker – which in the other direction runs out to the “Batt” post on your voltage regulator.

The wire running off the “I” or “C” post of the switch runs straight out to the coil.

If you look at the back of the switch and put the post that says GA/RAD up at the 12 o’clock position, clockwise from there, the first post (at about 4 o’clock) should be power in (Batt, P,or B) and then continuing clockwise, the third post should be “I” or “C” and goes out to the coil.

I sent these to you via e-mail but thought I'd post them for everyone else:



Here's the signal flow - ignition switch is on lower left of drawing (thanks Bob)

 

If yo uhave electric wipers you will need a 12 volt wiper switch

Julie why would you need to change the wiper switch? Could you put a Volt-A-Drop and keep the current switch? Also when changing out the lights that would include the instrument lights, correct?

Thanks

 

julie,thanks for the step by step.like blockerboyscusttoms,i have yet to understand how to use this forum.i have a 50merc m-68,first i just want to get it on the road so i can drive it.i would like to do this conversion,i think it would be much better in the cold of alberta winters.do you or anyone else have any yah or nay on the IVR voltage reducer?i found this site somewhere(??????)and he said for 5 buck in parts for radio shack he made his own reducer.i think it was called ..cristoohers 66 mustang retorstion and modification.i dont know how to post a kink or even a piture on here or i would put up for you to check out,if you havent already.

thanks

 

one more question,is there something besides the chev one wire i could use?the thought of putting anything chev in or on my truck makes me ill.

thanks again

 

Vintage tin---don't know about making the reducer other than to say voltage reduction usually results in heat dissipation off of a resistor so be careful with the homemade stuff. I used the individual step downs for the gauges on my '49 M-47 with great success and I know Mid-Fifty sells units that will handle larger amp loads.

As to the alternator, it killed me too, but the GM 10 SI three wire was such an easy set up that it made no sense to do otherwise. The one wire apparently works well too, but I don't like the idea of revving my cold flathead for the sake of a couple of other electrical connections. That said, most any alternator you can make a bracket for will work (don't forget the regulator if it's not internal like the GM) or you can spend big $$ and buy a generator look a like that bolts right in.

I want the option to go 100% stock someday but in the meantime, 12 volts is a really nice "non intrusive" kind of upgrade. Consider the GM alternator as a "temporary expediancy". I don't think anyone here will fault you for that!

Ryan