69 underdash wiring

[95venom 10]

been working on it for weeks, oil pressure gauge and water temp do not work

sending units are new and wiring to under dash feed is new. i am thinking we are missing a ground somewhere or something but can not find anything... we have guage lights... um.. lets see... new circuit board.. thought that was it.. one of the wires taht is loose is only hot when the door is open like there was a door light on the drivers side as well. wire to lights is only hot when lights are on and both ends of fuse are dead until lights are on. ??? oh btw its 69 mustang fastback 302 2v c4 auto.

original ac car, has cig lighter.. idk if anything else needs to be known

i HATE when someone messes up wiring.

we are to the point of new harness but for the life of me i can not find one for 69?? there are some universal on ebay..... and painless wiring has one i believe. jeez... this is all that is holding us up... i want to build cobra motor!!

any help is greatly appreciated, thanks

-Matt

 

 

 

older pic...

[69RavenConv 286]

It might be the constant voltage regulator (CVR) on the back of the instrument cluster. It supplies 5V to the sending units on the temp, oil pressure, and fuel gauges.

 

As for the hot-when-the-door-is-open wire, I think all Mustangs had under dash courtesy lights, and deluxe interiors had lights in the doors as well.

[95venom 10]

It might be the constant voltage regulator (CVR) on the back of the instrument cluster. It supplies 5V to the sending units on the temp, oil pressure, and fuel gauges.

 

As for the hot-when-the-door-is-open wire, I think all Mustangs had under dash courtesy lights, and deluxe interiors had lights in the doors as well.

also put in new constant voltage reg on back of cluster and no change.

[RogerC 136]

I would check all connections against a wiring diagram. Verify the wire colors at each connection. I know its time consuming but until then you don't know for sure its correct. There's a ground connection on the left side top of the lower dash.

 

Sharp car BTW

[bcorbin 10]

95, Does the fuel gauge work? All three (Fuel, Oil and Temp) are fed 5 volts by the CVR to one side of each gauge then through each gauge's sending unit (which is basically a variable resistor) to ground. The value of the sending unit's resistance to ground varies between about 10 ohms and 80 ohms depending on temp, oil pressure and fuel level. The resistance reading I get across each gauge by iteself is about 13 ohms. If the Fuel gauge works and the other two do not that is a clue. I am currently doing some troubleshooting of my own on these gauges.

[69RavenConv 286]

also put in new constant voltage reg on back of cluster and no change.

 

Hmm, does the CVR have a good ground?

Is the engine block ground strap hooked up?

[Juice It 10]

DId you take the actual gauges out of the cluster for any reason? I had this same issue and the problem was that if the two bolts holding in the gauge are not perfectly straight in the little cardboard washer they will touch the metal on the housing and the gauge will not work. I went through everything when I had this problem and came across a post stating this and sure enough mine was a tiny bit off and touching and that was it, problem solved.

[95venom 10]

DId you take the actual gauges out of the cluster for any reason? I had this same issue and the problem was that if the two bolts holding in the gauge are not perfectly straight in the little cardboard washer they will touch the metal on the housing and the gauge will not work. I went through everything when I had this problem and came across a post stating this and sure enough mine was a tiny bit off and touching and that was it, problem solved.

I put new gauge glass in? could this be a problem?

hm....

that wouldb e a nice fix.

well i pulled the harness out and somebody has done some tampering but nothing that i can find taht would cause this.

everying related completes a circuit.. engine ground strap is connected. fuel gauge does NOT work.

 

 

the ground tha goes to the dash.. there is a bolt like it should have a ground going to it but he closest groudn wire is grounded to the bottom of the dash.

 

in the harness i found a small black cut wire but it is no where close to where i thought i was missing a ground.

are the front turn signal/fog light deals supposed to be on when the headlights are on? I think they used to be and after re-installing harness, they only work when the switch is pulled to the first position..

thanks for all the help guys, I appreciate it.

Edited December 28, 2008 by 95venom

[95venom 10]

I put new gauge glass in? could this be a problem?

hm....

that wouldb e a nice fix.

well i pulled the harness out and somebody has done some tampering but nothing that i can find taht would cause this.

everying related completes a circuit.. engine ground strap is connected. fuel gauge does NOT work.

 

 

the ground tha goes to the dash.. there is a bolt like it should have a ground going to it but he closest groudn wire is grounded to the bottom of the dash.

 

in the harness i found a small black cut wire but it is no where close to where i thought i was missing a ground.

are the side marker lights supposed to be on when the headlights are on? I think they used to be and after re-installing harness, they only work when the switch is pulled to the first position..

thanks for all the help guys, I appreciate it.

I did move this wire to the top

[95venom 10]

DId you take the actual gauges out of the cluster for any reason? I had this same issue and the problem was that if the two bolts holding in the gauge are not perfectly straight in the little cardboard washer they will touch the metal on the housing and the gauge will not work. I went through everything when I had this problem and came across a post stating this and sure enough mine was a tiny bit off and touching and that was it, problem solved.

YOU FIXED IT THANKS BUD.

temp/fuel gauge were grounding out. ahhh i started it and just watched that oil pressure climb up... ohh yeah.... anyway still have front turn signal problem. im so relieved though... hopefully i can put it all back together.. get my exhaust welded up... and drive my baby.

[bnickel 10,004]

YOU FIXED IT THANKS BUD.

temp/fuel gauge were grounding out. ahhh i started it and just watched that oil pressure climb up... ohh yeah.... anyway still have front turn signal problem. im so relieved though... hopefully i can put it all back together.. get my exhaust welded up... and drive my baby.

 

you don't have a problem, the parking lights only work when the switch is pulled to that position, NOT when the headlights are on. most pre 70 or 71 cars are like this. i think you can make them work when the headlights are on by using a 70 or 71 mustang headlight switch but the 69 switch won't allow them to work with the headlights on

[95venom 10]

you don't have a problem, the parking lights only work when the switch is pulled to that position, NOT when the headlights are on. most pre 70 or 71 cars are like this. i think you can make them work when the headlights are on by using a 70 or 71 mustang headlight switch but the 69 switch won't allow them to work with the headlights on

cool thanks man.

thanks for all the help guys.

[Juice It 10]

YOU FIXED IT THANKS BUD.

temp/fuel gauge were grounding out. ahhh i started it and just watched that oil pressure climb up... ohh yeah.... anyway still have front turn signal problem. im so relieved though... hopefully i can put it all back together.. get my exhaust welded up... and drive my baby.

 

 

Cool, glad it worked. I tried everything before I read this as well. Those little cardboard washers get stretched and it grounds out.

 

Jeff

[95venom 10]

Cool, glad it worked. I tried everything before I read this as well. Those little cardboard washers get stretched and it grounds out.

 

Jeff

ok well I get the whole interior put back together and tis not working :censored:

 

pulled it out and messedwith it again and did the same thing, even put electrical tape down so it couldnt ground out and its not working!! have not checked fuses yet though... I need ot finish, going to put exhaust on it tomorrow.

[95venom 10]

fuses are good! what could have happened? the gauge was tight...

[95venom 10]

mk well the new circuit board the snaps for the cvr are just a little to wide and one had come unsnapped so thats the oil pressure problem...

 

but all th lights never worked, only the right 3/4 of them.

now the only light that works is the oil pressure gauge. turn signals light up and brake system lights up.... if one bulb is out does that make the rest not work like it won't let it complete the circuit? well i checked and every bulb completes the circuit!...