64 chev T10 tail lights & speedo & gas gauge

[pheengurs]

I just recently bought a 64 chev stepside shortbox 4x4!
( some pics and info are listed here:
http://www.bomp-bomp.com/forum3/viewtopic.php?f=4&t=604 )
It's got a more modern HEI gm 350 motor, and a 4-speed floor shift... I sure love it ... however the truck has some wiring issues... I have done alot already, and have run into a very confusing issue with the tailights...

When I bought the truck the tail lights were not working, so I replaced them with a set of aftermarket lights equipped with backup lights... without changing wiring, I just hooked up the new lights, and they didn't work at all...

so I tested the firewall connector, and replaced the wiring from the firewall connector back to the taillights (using same factory colors (brn=pwr, yel=drivers signal, dkgn=pass signal). (taillights have a separate wire for the backup lights which is not hooked up at all-not sure how to get that to work...)

(headlights and front signals work fine)

OK, so here's the lighting issue:

-no park lights (front or back)
-rear signal lights: both go off instead of just one, like hazard lights, only I can find no hazard lights button anywhere
-when light switch in park light position, and signal engaged, the license plate light flashes in time with signal (this does not happen when light switch fully engaged
-when light switch in park light position, and signals not engaged, the license plate light intensity varies quite a bit (could be a grounding issue?)
-brake lights work!


Speedometer not working:
-cable looks in great condition
-cable is secured from dash to transfer case (was thinking of unscrewing cable from xfer case, and using a drill to see if I could get a reading from the speedometer, but I am having troubles getting the cable loose...)
-how does the speedo work is it totally mechanical or is there electricity going to it as well?
-was the factory voltage 6V? maybe I need a voltage reducer because I'm now running a 12V HEI motor???

Gas Gauge always at full:
-have read conflicting reports on the net that this should read 30 ohms when full or 90 ohms when full...
-have read conflicting reports on the net the gauge originally ran on 6V or 12V....

any help is appreciated, and I'll try to respond at least once a day

[zenish]

these trucks are bad for losing the ground to the bed.run a wire from the frame to the bed.see if that helps.unhook the gas guage wire at the sender.if the guage goes to empty you have a bad sender.if it stays full,the wire from the guage may be bare somewhere and grounding out.unscrew the cable at the speedometer.drive at a low speed and feel if the inner cable is turning.if not you can pull it out from the speedo end to see if its broke.

[pheengurs]

thanks Zenish, those suggestions helped narrow things down ..

-- I made new negative ground cables from battery to frame, from frame thru firewall to dash, and from rear frame to taillights & license plate light... the signals work normally now. however the tailights now go on as soon as the ignition is turned on - which could be something to do with the brake light unit, as nothing changes on the lights when I depress the brake pedal... I'll have to run the wiring down for that now...

-- the speedo cable is fine. I took the cluster out and apart. Turns out the speedo arm is busted, and the movement of the speedo is not 100% fluid, so the speedo is busted beyond my ability to repair within the confines of my parking space...

-- the gas gauge reads full with no wire to sender and with a new wire to sender from fuse box...there is voltage on the pink wire to the gauge connector - something like 5 volts or so, and nothing on the tan wire...and no resistance on either between fuse box and connector ends, so the wiring is good there... I guess it's the gas guage itself then?

I'm going to run a new ground wire from the front lights to the frame today, to see if that makes any difference to the lighting situation, as well as run down the brake light wiring...

[pheengurs]

ok -- latest update:

-tailights are good...dunno if removing instrument cluster had anything to do with it, but my Dad came over to help last weekend, and the tail lights were working as they should be... I guess we'll see what happens there once I start installing my new homemade cluster...

How do I test the Ohm range of the sender so I can purchase the correct gauge? Where exactly do I put the leads? with ignition on or off? would it matter that the cluster is out of the truck?

Anyone ever buy one of those after market universal sending units and get it to work in the in-cab gas tank?

[64 C-10]

Zinish, thanks for the good advise. I've been watching this thread because my '64 has the same problems.

May be a factory defect that's covered by the warranty.

I'll do the tests this weekend if the weather allows and post the results.

[pheengurs]

Originally Posted by pheengurs

How do I test the Ohm range of the sender so I can purchase the correct gauge? Where exactly do I put the leads? with ignition on or off? would it matter that the cluster is out of the truck?

Anyone ever buy one of those after market universal sending units and get it to work in the in-cab gas tank?

-->any help with testing the sender's ohm range, would be cool!

-->zenish - how'd it go?

grounding was definitely the issue for the lights... after adding new grounds all over the place, the lights work totally normal.

I ended up buying all new autometer gauges, including a new gas gauge and sending unit. I plan to test the existing sending unit on the new gauge to see if it works at all.. otherwise, I guess I'll have to replace the sending unit too... I made up an instrument cluster template from a roll of some roofing aluminum flashing... I have a bit to cut the 4 holes for the 2" gauges, but getting the 3-7/8" holes for the speedometer and tach are going to cause me a problem... home depot has bits that size, but they want more than thirty bucks for one bit...so I'm going to have to find another way to cut those holes...

[pheengurs]

well, I've finished the cluster... it's now painted and ready to install as is.. though there are a few minor things I'm still trying to work out... as I mentioned I'm using thin sheet metal, which is easy to work with, but I'm not sure how I'm going to mount the signal lights and high beam light... I have preliminary holes cut, but I'm still not sure how it's all going to fit...

my autometer gauges came with these colored light covers...which I'm going to use in the gauges, but I figured for now, I'd use the green ones over the signal and high beam lights and they'd just protrude outward from the cluster, until I can afford one of those fancy billet aluminum units...

I also ran wiring and a manual switch to the back up lights... it's not the best option, but it will do for now... the good thing about making my own cluster is I can now make my own custom switch plates for my switches...

while I was testing the lights with the light switch in the middle position, I noticed an odd sound coming directly from the light switch... similar to popping or sizzling, but there was no smoke, no heat on the switch chassis -- the front signal lights, which go on like running lights when the switch is in the middle position, were flickering... I'm glad I ordered a new light switch, because this one is definitely bad...

I also replaced the turn signal blinker unit while I was down at the fuse panel...

so hopefully this week, I'll get my switches and ebrake parts, and then I can reinstall the gauge cluster, hook up all the gauges and drive around town for a bit!

[Longhorn Man]

I have my back up lamps on a toggle also.. I highly recomend getting one with an LED in the end. It's kinda embarasing when you get pulled over and told your back up lamps are on.

[pheengurs]

well, I've installed the gauge cluster, new headlight switch, and front driveshaft U-joints into the truck...

you can see pics of the entire truck progress here:
http://www.bomp-bomp.com/forum3/viewtopic.php?f=4&t=604

I know, I know --
(sorry about not having pics in my posts, but most of my pics are larger than this forum's size limits.)

I didn't want to run the power for the electrical gauges from the ignition switch, as I doubt it was designed to handle the load... so I used one of the blade terminals at the fuse box and installed an inline fuse between the power and the switch, and another fuse between the switch and the gauges power... The terminal only has power when the key is turned on the ignition, (and doubly with the switch in the off position) I don't have to worry about the gauges draining my battery...

my use of 2 layers of roof flashing aluminum, seems a little flimsy with all the gauges installed... I may have to add a few more layers, or design something more sturdy, or break down and buy a fancy billet aluminum bezel...

for the signal lights, and high beam light, I used the autometer rubber light condoms and cut holes large enough for them to squeeze through, and then used thin diameter lock washers to hold the lights securely in place...

overall, I really dig the look of my new cluster...

I also bought a new ignition switch bezel nut, but I cannot figure out how to get it on... it's too small in diameter to fit over the top part where the key goes in.. there are two small holes in the top part where the key goes in, but I cannot figure if it's supposed to be able to come off or what you'd think you should be able to remove it, as isn't it possible to replace the lock cylinder without replacing the entire ignition key unit ???

the new headlight switch doesn't make that crackling noise when the switch is in the first position, which is good.

I still need to run the sensor wiring through the firewall, and install the sensors, as well as run new wiring & a fresh ground to the fuel sending unit...

[kwkenuf]

Remove your lock cylinder by inserting a straightened paper clip in one of the holes (can't remember which one but you will feel spring pressure on one) depress the detent through the hole with your paperclip then rotate the cylinder counter clockwise past "off" with the key installed. Once you get the cylinder out you can remove the old bezel, install the new one and reinsert the cylinder.....

[pheengurs]

well, I tried getting that cylinder out, and it's not working... but I'll keep trying. I don't feel any spring in there, and it's not turning to the left past 'off' more than 1/2 a milimeter... so I guess I have to keep trying, I'm sure I'll get it...

bad news is my dash lights quit working... they were working last week, and now aren't getting power to the bulbs... I am getting REAL tired of this wiring, and rewiring, shyte!!! Anyway, I am bypassing the original dashlight wiring, and am gonna just run the damned lights from the power and switch I've setup for the gauge power... as for the old wiring? well, I will disconnect as much as possible, and what cannot be easily removed, in this venture, will be taped up, and ziptied out of the way... as it's quickly turning into a rat's nest behind the dash...

[pheengurs]

a bit of an update for y'all...

my new gas gauge doesn't work with the old sender (big surprise) so I pulled the old sender out, and sure enough, it was toast... so I grabbed the new sender I bought with the gauge, and noticed something -- there's no fuel line running through the top of the new sending unit chassis!

so I meditate on that one for awhile, and try again to get that damned ignition lock out... it's still not cooperating!

so I go back to the sender... I decide to remove the sending unit itself from both pieces, and try to attach the new sender to the old one that has the fuel line going through it .. man I had a hell of a time with this ..

my brother the welder, tried to stick weld em together, and it would not penetrate the new metal on the sending unit. I guess the new one has some kind of coating over the steel that won't adhere with standard stick welding technique...

so I tried soldering it, which with enough solder, held the bloody thing in place, however the spot I soldered it to, did not allow for the small diameter hole it had to fit through to get back into the tank...
back to the drawing board...
well, it came down to using two small hoseclamps, to hold the new sender onto the old sender chassis. I soldered a new ground on, put everything back into the tank, and wired up the sender and it now gives a reading on the gas gauge!

mikeguyver to the rescue!

I'm not sure if it is totally accurate or not, there isn't much fuel in the tank right now, but at least I'm getting some kind of reading instead of nothing...

I also had to completely bypass the stock dashlight wiring for the gauges, as for some reason the old wiring failed after two days. I ended up installing a new 6 point fuse panel, and running the power seat, gauges, backuplights, and heater fan motor on the new panel... Now everything works as I want it to, which is nice for a change... There is only one thing left to do as far as wiring goes and that is upgrade the headlights to allow for newer halogens...but that is for a new post...