Grounding points

[Higgins56]

Hi,

my 71 mach1 has some electrical problems.Originally a 302 and now 429.

The car I bought as half assembled restored car and now I am doing the rest putting the parts back...the original 71 wiring harness was bad so I got a 72 wiring harness ( from a high optioned car which my car was not)which is now installed. I bought a tacho cluster and the 72 harness is a tacho harness. There is AC in the car ( original).

MOST of the things work, like:

-car starts with the key

-alternator loads the battery

-headlights -low and hi beam

-wipers

-cigarette lighter

-flasher ( 3 of the 4 lights flash)

-dashboard lights

-break lights

-reg plate light

-marker lights

-fuel gauge

-left side turn signal warning light ( with the flasher)

but then there are some that don't, like:

- turn signals

-horn

-washer

-back light is not getting feed ( 12v)

-the gauge cluster does not have the back lighting

-right side turn signal warning light ( with the flasher)

My friend was assuming a ground problem... but where can I check the grounding points - any map or list where they are located.

Does anybody have another clue ?

 

[midlife]

Turn signals and horn may be due to a bad turn signal switch.

Back light and right side warning light may be due to bad bulbs or bad connections on the ground lugs on the bulb sockets.

Gauge cluster lights have grounds via the connector plug that goes into the circuit card; that line is tied to all of the other grounds. You might want to sand those curved connectors a bit with a scuff pad (I like 350 grit).

 

[wwhite72]

Also, back lighting is so dim that you may need to check with voltmeter before you decide that it isnt on.

 

[midlife]

Also, back lighting is so dim that you may need to check with voltmeter before you decide that it isnt on.

Yup...forgot that one...make sure the headlight switch is rotated all of the way. If still no lights, turn it the other way (I forgot whether it is clockwise or CCW for maximum dash lamps).

 

[Higgins56]

Also, back lighting is so dim that you may need to check with voltmeter before you decide that it isnt on.

Yup...forgot that one...make sure the headlight switch is rotated all of the way. If still no lights, turn it the other way (I forgot whether it is clockwise or CCW for maximum dash lamps).

Thanks of your comments !

I cleaned once more the fuse box ( with a fine sand paper)and guess what - most of the missing lights were found.

The only thing that is not working at the moment is the horn and the reason is a broken contact to one of the two copper studs.

I wonder if I can repair it by soldering it back.. ? I guess it is a part of the turn signal switch...

 

[midlife]

Good luck soldering copper contacts and keeping them in place; they will be under a lot of high stress. Time to replace the turn signal switch for sure.

 

[MechEng]

Also, back lighting is so dim that you may need to check with voltmeter before you decide that it isnt on.

Yup...forgot that one...make sure the headlight switch is rotated all of the way. If still no lights, turn it the other way (I forgot whether it is clockwise or CCW for maximum dash lamps).

Thanks of your comments !

I cleaned once more the fuse box ( with a fine sand paper)and guess what - most of the missing lights were found.

The only thing that is not working at the moment is the horn and the reason is a broken contact to one of the two copper studs.

I wonder if I can repair it by soldering it back.. ? I guess it is a part of the turn signal switch...

When you say copper studs are you referring to the two that stick out of the turn signal assembly and ride against the back of the steering wheel? If so, don't even bother with solder, just get a new switch. Leaded solder wont stand up to that kind of stress.

 

[mityman]

I was able to get an NOS turn signal switch for less than 1/2 the price of remakes. Watch ebay for some good deals on one if your not in a rush for the switch.

 

[Higgins56]

I was able to get an NOS turn signal switch for less than 1/2 the price of remakes. Watch ebay for some good deals on one if your not in a rush for the switch.

Thanks again of your comments.

OK - I have to consider the soldering the copper stud once more...