New to Forum and need help finding a ground issue

[1979Hertitage]

We have a 1979 Heritage that is having some grounding issues. I have checked and replaced every fuse. There are a few issues. The right from passenger light only works when flashers or turn signal are turned on and the white side markers on both sides do not work. I have replaced all the bulbs. The next item is the moonroof and trunk relay does not work. If i hook up electric directly to the moon roof motor it works.

None of the light guages work in the dash, meaning the engine, buzzer for seats, Brake light etc. I think this is related to the moon roof issue.

Does anyone have any input. I have been up under the dash so many times and almost got wedged in there so good I almost did not get out:)

Any help is appreciated.

[BirdShepherd]

I've hear of this same type of problem with the 77-79 T-Birds.
Will get back with you shortly with some feedback.
Tim

[1979Hertitage]

Thanks Tim!

[BirdShepherd]

Based upon your description of the series of electrical problems in your Heritage, here is some feedback:

1) The moonroof & trunk release are on the same ground and so are indeed related. This is ground 1605 which is located right near the moonroof switch along the roofline near the windshield. Also, as is common sense, the moonroof & trunk release are on the same fuse, fuse #2. However, the speed control, illuminated entry, rear deice are also on fuse #2, and these apparently work for you----right?. First, I'd check the ground carefully; remove and clean all terminals. Then I'd check to see if power is actually coming into moonroof relay/moonroof switch. There's a possibility of a bad connection (rust, corrosion, split, or even a ground out), somewhere between the fuse box and the relay/moonroof switch. Track the wire carefully with good light and with your best pair of glasses on. (Years ago, both my headlights seemed to flash on and off; problem was a partly bare wire grounding in and out in the trunk area--too many things piled on top of the wire caused damage to the wire; covered up the wire with electrical tape and the headlight flashing stopped).

2) As far as the light issues, there's a possibility that these series of problems could be caused by a bad headlight switch. The headlight switch is like 'Grand Central Station: everything flows in and out of it. (My tail lights did not work on one occasion--it was a bad headlight switch). Your headlight switch may have overheated in the past, causing one small but key connector to melt or be damaged. Even though the headlights are working on your Heritage, there could still be a problem with the switch. The switch is relatively easy to find and replace, and if it's not the problem, you'll have a spare switch. Take it out and inspect it very carefully. Look for any burn spots or damage. If you see anything suspect, invest in a new one.

Best wishes to you. You will get to the bottom it. Stay in touch. Tim

[1979Hertitage]

Relieved and then frustrated all at same time!! ;) I vaguely enjoy this ground challenge as it is a great feeling to fix something yet frustrating when something else goes wrong. Yesterday for some reason the power windows stopped working and blower on heat stopped working. But the defrost works fine. As I am looking for blown fuses and checking anything possible I noticed that NOW THE DEICER WORKS (it also did not work previously). I think HMM let me check the trunk release it WORKS. THEN I put back on the switch for the moon roof and It worked. I also noticed the door open light is now working. BUT as I stated the power windows do not work now.

I have the 1979 Electric and vacuum manual and I am very slowly understanding this manual. I just figured out where all the grounds are located. It also states exactly what you stated in your post. The weather is supposed to be nice today so I plan on looking at As many grounds that I can today and also tracing the wires for side lights today.

I will also look into the switch you stated. I remember reading about something you said back in December. IS the switch you are referring to the pull out switch on the dash that turns the headlights on and off?

Thanks in Advance!

[BirdShepherd]

If you have the electrical diagram and are slowly understanding it, that is good. Makes all the difference if you know the design and where the flaws and failures might occur in that design.

Per your question about the headlight switch, yes, it is the switch under the dash.

To remove the switch, with one hand and finger, reach underneath the dash and find the switch itself. Then, with your finger, find a small metal button located on the underside of the switch. Push the button in and, at the same time, with your other hand, pull the knob (on the dash) out with much force. Depressing the button on the underside releases the knob. It may take a few tries to pull it out. It is brutal on the finger you use to depress the knob. I sometimes use a quarter coin to depress the button.

Then, unscrew the bezel (on the outside of the dash) from the switch (on the inside).
Once the switch is released, unplug the electrical switch and then remove the three rubber vacuum lines: keep track of the sequence of the three colors painted on the rubber lines.

Your switch should now be free to inspect. Inspect both sides of the electrical plug: male and female.

You will get through this. Perhaps a step at a time. But you will win!
Regards, tim