Quick dash ground/voltage regulator question

[TexasEd 188]

I recently replaced my dash lamps with LED, new circuit board and new voltage regulator.  Gauges worked before.

LEDs work - does that mean I have a good ground for everything else?

Gauges do not work - Is this most likely new voltage regulator.  Thinking of taking it out and putting old one back in.

 

Thoughts?

[Midlife 814]

7 minutes ago, TexasEd said:

I recently replaced my dash lamps with LED, new circuit board and new voltage regulator.  Gauges worked before.

LEDs work - does that mean I have a good ground for everything else?

Gauges do not work - Is this most likely new voltage regulator.  Thinking of taking it out and putting old one back in.

 

Thoughts?

Nope: when you replace the circuit board, you have to loosen the nuts holding the various gauges.  The posts can easily contact the metal housing when reinstalling and tightening the nuts, shorting out the CVR output  and the gauges will not work.  This is a chronic problem for 69/70 dash clusters.  The cheapest solution is to remove the circuit card and place black electrical tape over the rectangular cutout sides so that the posts won't contact the metal housing.  Re-install the cardboard insulation pad, the circuit card, and tighten the nuts. 

As a check, you can measure the resistance between each post and the housing metal.  If you see 1 to 14 ohms, one of the gauges is shorting out, causing the others to short out too.  The ammeter, if shorted, will cause a massive short and because the lines are not fused, can cause a fire.  Bad design by Ford.

[TexasEd 188]

10 minutes ago, Midlife said:

Nope: when you replace the circuit board, you have to loosen the nuts holding the various gauges.  The posts can easily contact the metal housing when reinstalling and tightening the nuts, shorting out the CVR output  and the gauges will not work.  This is a chronic problem for 69/70 dash clusters.  The cheapest solution is to remove the circuit card and place black electrical tape over the rectangular cutout sides so that the posts won't contact the metal housing.  Re-install the cardboard insulation pad, the circuit card, and tighten the nuts. 

As a check, you can measure the resistance between each post and the housing metal.  If you see 1 to 14 ohms, one of the gauges is shorting out, causing the others to short out too.  The ammeter, if shorted, will cause a massive short and because the lines are not fused, can cause a fire.  Bad design by Ford.

Thanks, I was careful about getting the carboard insulation in what looked like the right place but I did not check continuity/resistance between that and ground.  

Pulling the gauges is a pain in the ass.

 

[TexasEd 188]

@Midlife

here is what I did. After this there was no more short on the other gauges so I left them alone. 
the second picture is of the ground between the circuit and the housing. No wire goes there, correct?

[TexasEd 188]

All gauges working  Gas gauge shows a third with half a tank. I tried to adjust the sender before I put it back in  guess I’ll live with it.

[Rich Ackermann 174]

1 hour ago, TexasEd said:

@Midlife

here is what I did. After this there was no more short on the other gauges so I left them alone. 
the second picture is of the ground between the circuit and the housing. No wire goes there, correct?

Not sure what the hole is for, but looking at a picture of mine before I disassembled it, looks like the threads of a screw coming thru the hole. I had small round rubber insulators at the base of each gauge terminal post and a thin gray strip of cardboard over the posts and between the metal gauge cluster body and the circuitboard. Pics below..

[Mach1 Driver 560]

2 hours ago, TexasEd said:

@Midlife

here is what I did. After this there was no more short on the other gauges so I left them alone. 
the second picture is of the ground between the circuit and the housing. No wire goes there, correct?

No, no wire. If you have a non-tach dash the picture below may help, read #7. Also, ground wire #57 Bk connects to #8 in the plug. With a stock gas gauge, I would use Meter Match to correct the error.

 

 

[det0326 179]

If I remember correctly that screw has to be in there. It completes the ground circuit on the printed film. I guess they didn't have a good way to get from point A to point B with printed circuit so they used the cluster housing to connect the two circuits.

[Mach1 Driver 560]

Yes, Dave you're correct, screw at #7 in my picture and in his should be there. But I believe he is referring to the hole where the plastic part normally protrudes through the hole above the light. Its hard to see in my picture:  

[TexasEd 188]

No I was talking about the ground screw. I just wanted to make sure it was not wired to the chassis for ground. My gauges get good ground from the top two mounting screws.
 

I think the plastic parts disintegrated from age. I did not replace them.  

[TexasEd 188]

All working now 

[det0326 179]

17 hours ago, TexasEd said:

All working now 

Texas Ed, how can u be doing 40 MPH and no steering wheel

 

 

 

 

p

Edited July 10, 2022 by det0326
Oh closer look I see steering wheel now just missing center piece. LOL had me wondering there for a moment

[aslanefe 333]

20 hours ago, TexasEd said:

All working now 

Do you have a link to LEDs you used and do they dim?

[unilec 57]

 

https://www.mustangtech.com.au/Content/pid=28.html

The original voltage regulators are a known culprit of poor or low gauge readings and gauge needle flickering.

This attachment is an upgrade that you can do yourself or a friend with limited electronic experience can do for you.

I have done this mod and several members have as well, so a small amount of outlay it worth doing. I did this mod a few years ago now and seem to work well, although my car is running, but still not on the road.

[TexasEd 188]

On 7/10/2022 at 6:59 PM, aslanefe said:

Do you have a link to LEDs you used and do they dim?

Don't dim.

https://www.customcarlight.com/ford/mp-6970-led-ga-xp-aqua-69-70-kit-mustang-gauge-led-lamps/

If I was doing it again I think I would get blue instead of Aqua.