Gary's 2 442-S

First of all let me say that all of the car's wiring harness is new. I bought them from M&H. All electical switches have been replaced, so they are all new as well. Now the problem is when I start the car the gen/hot indicator will remain on. Thats with the car being cold. I turn the head lights on and the fuel indicator goes back to empty and that is a big mystery to me. The car is 72 442. I thought maybe the next wiring harness has a wire maybe in the wrong place,but when I compare it with the old one, the wires are the same colors. I unplugged the voltage regular, which is also new and the gen light goes off but the hot one remains on. any one has any suggestions.

Rickman48

I'd be calling M+H for acouple reasons;
1] They made the harness and should stand behind it, and
2] They probably have more knowledge on electrical than all of us combined on this forum!!

Highwayman

My first rule of thumb, anytime weird stuff happens suspect a bad ground. Headlights affecting the fuel gauge is weird enough to qualify.

You could recheck the ground connections on the new harness and make sure the connections are clean. Maybe scuff the places the new harness attaches to with a Scotch Brite pad if needed to make a good connection.

Junkman

Check the headlamp dimmer switch on the floor. That switch if it has bad contacts inside of it, can give you a world of headaches until it fails completely. Then it will only melt the wires and the plastic connector. Also, using a wire with an alligator clip on one end, and a point on the other end, and just probe where there should be a ground. If the ground is the problem, then it will go away when you probe that item, and come back when you remove the probe. That is how I find bad grounds quickly..

Gary's 2 442-S

It has brand new dimmer switch also. I put the old dimmer switch back on and it still does it. I am leaning towards the idiot light gauge having a bad circuit. The reason I say this is because the bulbs on the gauge wont come on unless I ground the terminal leads when I have the lights on. The bulbs work as they should on the odometer and the clock once the lights are on. I now got to try to figure out how I can test the gauge.

Junkman

Ground the hieadlight switch and see what happens..

Gary's 2 442-S

Tried that no change. I decided to go ground to the housing and I pick up 12v when I turn the lights on. So then what I did I took the circuit board off and put tape on the back of the terminals. Put back together still getting voltage on the housing when I turn the lights on. I dont know that this should occurr but I would think not. Its appears that the circuit board is grounding up against the housing. This does not happen with the other 2 gauges

Highwayman

When you have an open circuit everything on the power side of the open will read full battery voltage. A loss of ground is an open circuit.

Lady72nRob71

Do you have the gauge grounding to the metal straps under the mounting ears? Is the strap grounded to the dash?

Gary's 2 442-S

Hey Rob, I really now believe that the problem is indeed with the wiring. The reason I say this is because I had to send this under dash harness back, because M&H sent me the harness that was for a car with GUAGES. Once I compared the new guage and the old one,I noticed that a couple of the wiring terminals/postions were different. I gave them a call and they told me when I called they sent me the wrong one,because I needed the one without guages. So I send it back and they tell me that its going to take 8 weeks to build the correct one. I advised them that I needed to harness way before 2 months and they then made the suggestion that they could rewire the harness to what I needed and that would take only a week or so. They sent it back to me in a couple of weeks. I compared the modified harness and the old one and everything matched up. So I am thinking cool. They apparently did not do something correctly because the problems I am experiencing are just too wierd so something is has to be wired incorrectly. I will be giving them a call tomorrow and see what solution they have. I will keep you posted.

Gary

Lady72nRob71

Here is a diagram so you can see if they miswired it.
Use the cluster connector picture at the upper right or the "from" column on the postit note...


For granny pac, the wiring should be arranged:
gray, dk green, connector key, dk blue, tan, open slot/black (only used if you have fasten belts light), pink, brown, tan/wht stripe

Gary's 2 442-S

mine are gray,dk green,, open slot, blue with white stripe,tan,pink,dk brown,tan with white stripe. the same on the old one. I do have a wiring diagram also and I have been using it as a guide. Now on the wiring diagram i have which is lamamented copy I bought off Ebay abou 3-4 yrs ago it shows the brown and the tan with white stripe being reversed, but on both the old harness and the new they are in the position I described first.

joe_padavano

The problem is almost certainly a ground problem. The ground straps are NOT part of the harness, so M&H won't be able to help. The straps are stamped sheet metal parts that go on the back of the plastic dash and are clamped with various mounting screws for the electrical components. If these are not installed properly, you'll have many problems. Also, as you apparently have already found out, the dimmer switch has NOTHING to do with your problems.

Gary's 2 442-S

I just got off the phone with M&H and they are also thinking that I have a ground issue. Once I described it that was their immediate response. I will check for ground straps when I get home,

Lady72nRob71

Ground straps can be seen here to the metal pieces in the screw holes:


Some should have a wire bolted to the chassis / dash

Gary's 2 442-S

Ok guys here is what I did this evening when I got home. I removed the dash. I then sanded all of the ground straps on the dash. I also scuffed the holes which the dash lugs go thru because I had repainted the dash housing. put everyhing back together the temperature/gen lights still remained on but now when I turned the headlights on, the fuel gauge does not go back to empty. So a bad ground did cause that as some of you guys said. So next what I did I took the temperature unit out of the engine block and I put the old one back in. That made the temperature indicator go out. The gen light still is on but not brightly so on tomorrow I will do some further trouble shooting and see whats going on with that. I the instrument bulbs come on that guage as they should. I will let you know what I find out about the generator light.

joe_padavano

Yeah, having multiple independent faults is ALWAYS so much fun to troubleshoot...