rwalker

Does anyone have a diagram of a fuse box on a 1966 cutlass?

joe_padavano

Are you looking for the wiring diagram or the labels? The wiring diagram is in the Chassis Service Manual for your year.

rwalker

anything that tells where fuses go ,cannot read on the fuse block.Thank You for Your reply.................Ron

Run to Rund

1966 fuse block
Top center, radio, 9 amp
Left column going down:
Heater/AC, 20 amp/25 w/AC
w/s wiper, 20 amp
power windows & antenna, 20 amp
Gl. Box, u/h, 9 amp
Tail lights, 9 amp
Stop lights, 20 amp
Dome & courtesy, 20 amp
Right column, going down:
Panel lights, 3 amp [mounted vertically]
Trans, 9 amp
Instruments, 9 amp
Spade lugs for power windows & antenna

rwalker

thanks for the info.Enjoy your olds

CutlassLegend

I am having a hard time find the short 9a fuse for the tranny. I was not able to find any at autozone today, anyone have any suggestions.

arcee1951

I'm having grief with the fuel gauge on my 66. It worked b4 restoration, but is registering past full now. Getting to the gauge is nasty, without taking the dash out. Any suggestions?

jaunty75

If it's registering past full, that most likely indicates an open circuit in the wire between the fuel tank sending unit and where it attaches at the back of the gauge.

The thing to do FIRST is to find this wire where it comes from the sending unit at the rear of the car and connects to the wire coming from the gauge. There is usually a pull-apart connector where these two wires come together in the area around the rear license plate. The wire coming from the tank is most likely orange.

Pull the connector apart and ground the wire coming from the gauge. With the ignition on, the gauge should immediately go to E. Unground it, and the the gauge should immediately go to F or past it. The gauge is nothing more than a 90-ohm resistor, with E representing zero resistance and F representing 90 ohms. With the wire disconnected from ground, the resistance is infinite, which is well more than 90 ohms, and thus the gauge will likely go way past F.

If the gauge behaves as described above, then your problem is not in the gauge, and you can stop worry about getting at it. The problem is then an open in the wire between the rear connector and the sending unit, an open in the ground wire between the sending unit and where it attaches to the body, or the sending unit itself.

If the gauge checks out, the next step is to check the ground. You'll have to get under the car in front of the tank and look for where it attaches to the body. This area is usually prone to the buildup of crud and corrosion, so disconnecting the ground wire and cleaning the contacts is a good idea. If doing this doesn't solve the problem, it's time to get the sending unit out and repair or replace it, or at least check the wiring to it.

White_Knuckles

Hmmm, on my '67, the fuel gauge maxing issue was at the connector pins bases on the printed circuit board behind the cluster. Reaching up through the dash and gently wiggling the round multi-pin connector brought the gauge and other mystery dead things like turn indicators back to life.

I ended up pulling off the connector, all lamps and screws and slipping the board out without tearing into the dash. Resoldering the board pins by scraping back the board trace lines and building up a heavy solder connection at all pin bases corrected it. If you can move the mechanically connected pins (sort of rivet mounted), post or PM me for details on board repair. New, replacement boards are also available.The large round connector is near the center of the board.

archeryshooter

yup mine does it too i have a new board also but if I wiggle the plug in the rear of the dash that plugs into the board and it works again. i think the plugs to loose on mine seems like a common thing

arcee1951

Well, it's been a long while, as I had some health issues. Let's see. I took the tank down and replaced the sending unit, hoping....that didn't work. The gauge still runs past full. I took the gauge out and swapped it with another one that I had laying around. As you look from the front, there is juice going to the left bottom side. I checked the ground underneath, seems to be good. I checked the hookup to the ribbon, by the back seat...nothing there. I tried wiggling the connection, to no avail. I replaced the idiot lights with gauges. Would the fact that those lights not longer work, make any difference?

archeryshooter

I still think its in your connection at the dash thats exactly what mine was doing or check panel if the post is loose you will need another panel Ron Roth is who I got mine from hes a good guy you can find him on here just do a search or hes listed under my friends

arcee1951

Thanks, arch. That will be my project today. I did try wiggling the round connection, to no avail, but will be standing on my head a while, today. I hate wiring problems.

White_Knuckles

No on the gauges/idiot change creating the fuel gauge issue. They are independent circuits. The failure being suggested is a complete open circuit from the round connector or the fuel gauge mounting. All the copper traces found on the printed board are large, heavy lines going to their respective lamps etc. The weak link are the mechanically fastened things. The fuel gauge has mechanical connections to the printed circuit board. Check its mount point fasteners. The round harness connector is also mechanically connected. The male pins are riveted to the printed circuit board. The rivets can loosen where the pins can float not making connection through to the gauge coil ground side. You have to pull off the connector and feel the pins for motion.

Edit: One side of the gauge has a (fused) +12V connection, the other side reads variable resistance to ground via the tank sender. So, (examples) a near empty tank reads 1000 ohms to ground. Half-tank reading is 500 ohms where a full tank may read low as 10 ohms. When there is no sender resistance or an open connection, it pegs the needle far right. If the tank send pin on the round connector is open, this problem occurs.

oldcutlass

I believe that the 66 sender works from 0-90 ohms, older cars were 0-35. If your remove the wire that goes to the gauge from the tank sender it will go past F. If you ground that same wire it will go to E. If it operates this way your issue is either the connections to the sender or the sender itself.

rroth01

I have 3 full Harnesses.Ill look tomorrow .I am kind of Beat up .Send me a personal Email and Ill send you a picture .We can figure it out.Ron 586-556-1234

White_Knuckles

Nice Eric, I forgot the ground/open test to verify needle response. Hey, how did you set your car front-rear level? Over-sized rear coils or air-shocks? I'd like to ditch my air-shocks.

rroth01, are you repairing these cluster PCB's? I'm guessing they're not out there except specialty rally-pack boards I've spotted? I advised earlier there are replacement boards available but now searching, I can't find replacements anywhere. They are repairable, mine was really bad.

oldcutlass

White_knuckles, I sent you a pm with the thread that listed the parts. I'm going try KYB shocks next as the Monroes aren't as HD as I would like.


Arcee, did you try grounding the wire at the tank yet?

arcee1951

This fuel gauge thing is driving me nuts. Yesterday, I found where the main wire comes through the body, and hooks to the "ribbon" under the back seat. I pulled this wire, and grounded it and, with the ignition on, the gauge remained past full. I tried a test light to see if there was any juice at all....nothing. I pulled the main round plug under the dash to see if I could feel any loose pins. They all seem firm. I ran a test light from behind the gauge, on the metal connectors that contact the gauge itself, from the hot wire, which is top left, as you are looking at it, to the ground, which is the bottom center, and I have juice. I'm just about ready to keep a log of miles driven, and try to keep the tank full, but I kinda wanted to take this bomb across country from here to Washington, California, Nevada, Colorado and back. That would be a pain.

jaunty75

This shows that you have a break in the wire between the dash gauge and this point. Your later comments and tests show that you have power to the gauge. So the problem is between the gauge and this point under the seat where you pulled the gauge wire off of the connector. You need to trace the wire from the gauge to the back seat and find where it's been cut or broken or whatever.

arcee1951

Well, it's narrowed down to one foot. I unplugged the ribbon that connects the front to the rear, and found that there is no break in the line, by using an ohmmeter. There are 7 wires running through this ribbon. I put a test light on the connection that hooks from the round connector to the ribbon. There is no juice from the board to this connector. Grrrr. I found another board, in case that is the problem, and all the pins are loose. Any other ideas? If not, how do you tighten the pins? Thanks.

55chev11

What’s the Gl box. U/h circuit for ? Thx

John Harbour

joe_padavano

This thread is from 2014. I hope it's fixed by now.

oldcutlass

Nice diagram though...

Vintage Chief

^^x2^^

irydasteelhorse

since you mentioned the trans fuse, i got to thinking......my trans hasnt been right in about a year. i know i looked at that fuse, and it was good. just out of curiosity i pulled it, and put in a fresh one, and VIOLA! it shifts right thanks for the help, even if you didnt know you were helping. fuse was broken at the end where you couldnt see it