1970coupe

hey guys i just replaced my bulbs in my dash and totaly disasembled it and resembeled them and the fuel and temp gauge dont work.when i stick the key in the ignition both gauge needles on each go past full. its not reading it at all. what could ive done? please help me out.

az1966

whne you say completely taken apart, what do you mean? if your just changing the bulbs why disconnect everything?,,need to know a little more

JamesW

You've somehow got your gage leads grounded, or you've got full voltage going to the gages. Take it back apart and reinspect all your wiring you messed with. Look for any wires common to the two gages...like a jumper or piggy back wire.

rst08tierney

you could have blown the voltage regulator. I did it when I took mine apart. If your cluster touches any metal or is not properly grounded it could blow. Take it off and give it a light shake. If you here it rattle the piece is gone. You can get a new one for 30 bucks at napa

kalli

had the same and in my case i just connected the cables the wrong way round.
the cable's going to fuel gauge. swapped and my empty tank was very full suddenly :-)

kalli

1970coupe

its a whole wire cluster. what do you mean? i have that backwards maybe?

F14chuck

Make sure you disconnect the neg lead off the batt before you take it out. You may fry the IVR. Also, its leads are fragile if its like mine. If its bad you'll get bad ie full readings.

If its like my 69 with the printed cicuit board, there are no extra wires to the actual gauges. Just theground wire that comes off the wire bindle, usually off to the left somewhere and grounds to the instrument brace.

So unless you broke the actual gauge, recheck to make sure you didn't damage the circuit board and recheck the screws on the back of the cluster. Also check the connector to make sure all the prongs and wires are intact, take some sand paper to the contacts if dirty. Its easy to mangle them if you reached around to take it off.

kalli

felt a bit guilty for telling rubbish with the connector (I always think: my car) and at the same time the lads here help me out constantly ... so I did a bit of a work for you. it might help, it might not help.
But you can always keep it as a reference because that took a while with those bl00dy spaghetti wiring diagrams ...



that's what your connector looks like (the broader bit on the left). took it from the wiring diagram. same thing

. |-----------|
|-| 123456789 |
| | |]
|-| ABCDEFGHI |
. |-----------|

I have labelled the 18 pins freely, they might have different numbers or none at all.
could have used 1-18, but used 1-I instead as it looks better in picture as no 2 digits)
the outer pins and pin "C" are not used


here's the list (all without warranty)

in disconnected status you should get the following readings ...

1 - unused
2 - RED battery +
3 - YELLOW Alternator
4 - GRN/BLK High Beam indicator (should have 12V+ when they're on)
5 - WHT/RED Oil pressure switch (should be ground when no oil pressure)
6 - WHT/BLU Indicator (no idea left/right, should be 12V+ flashing when indicator on)
7 - BLACK GROUND
8 - BLK/GRN IGN+ (from ignition switch)
9 - unused
A - unused
B - GRN/WHT Indicator (no idea left/right, should be 12V+ flashing when indicator on)
C - unused
D - RED/WHT leads to "TEMP sender" which is connected to ground on other side (dep on TEMP, the resitance to ground changes)
E - YEL/WHT leads to "FUEL sender" which is connected to "low fuel relay" on other side (GRN/WHT)
F - VIOLET Brake Warning (no idea... low brake pads ? handbrake ???)
G - GRN/RED going to Alternator Regulator (port A)
H - BLU/RED going to Radio (no idea what for ...)
I - unused

first of all I hope that the 2 problems are from the same cause. I don't know how the "low fuel relay" uis switched,
so I cannot tell what this should read.

But the temp gauge is easier. It would be so much easier if you had a high temp warning light. so we could compare (is it on or off)
I can't see one hooked up to the connector though :-(

GROUND--<sender>--<gauge>--12V+ (it should be like that)

the sender is only a resistor that changes with temperature and the gauge is a "Voltmeter" that is hooked up.

I don't believe that ground is gone on the sender as this is screwed to the block, you would have all sorts of problems then.

2 options
a) sender works as in: low resistance when cold
b) sender works as in: high resistance when cold
I don't know without a 1970 stang to measure on, but I suspect b): more volts when warmer (means needle goes against spring)

So from this:
either the temp sender is shot and going to full ground (don't believe that because of fuel gauge same problem),
or
you have ground on the connector (no voltage difference between ground and RED/WHT cable) --- can you check that ?

I'd check, how much resistance is there between ground (BLK) and RED/WHT). 0 resistance or infinite would mean that the sender or cabling has a problem. Anything else this side is ok (which I suspect)

... here's the end of my Latin ...


If you have taken the cluster apart then my first guess is that something inside screwed up?!?! .. sorry that's all i can say to this)

I originally checked the diagram, to see if there's a swap on opposing sides, but the fuel and temp sender cables going to the connector are reight next to each other.


I don't believe the connector is the wrong way. doesn't seem possible and you'd fry a few fuses with that (at least latest when you flick on the indicator ...)

make the most of it ...